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300 ultra mag accuracy problems

28K views 52 replies 21 participants last post by  clarke 
#1 ·
Hello I am new to this forum and this is my first post. I am going on my first elk hunt to Colorado this fall and am planning on taking my 300 ultra mag, but I am having some accuracy problems. I am not sure if it is me or the gun.

I am shoot hand loads out of a Remington 700 BDL with a 26" barrel, the hand loads are 180 grain swift scirocco II over 96 grains of H1000.

The problem that I am having is that my groups out of a cold barrel at 100yds. are around 2 to 2.5". Now I am not looking to shoot 600yds. but I do want to be confident out to 300 to 400 yds. The funny thing is that after the barrel gets hot the groups come into about an inch or so which would suggest that it is the shooter. (me) However I am shoot off of a bench with sand bags and feel really solid. I know the ultra mag has a pretty big kick but it does not seem to bother me much. I have shot the gun a fair amount it always is the same 2 to 2.5" groups then it comes into an inch. Does this make any sense or is it just me? I also have a 7 mag and have no problem shooting sub moa with it, so I am not so sure that it is me. Any advice would be greatly appreciated.

Thanks
Jason
 
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#2 ·
sounds like it's probably a bedding problem, as if perhaps when the barrel is cold there is some pressure or stress at some point of the action... then when it gets hot it "relaxes" if you will.

this is just a theory of course.

you could start by checking your action and scope screws, and trying several different factory loadings to see if it may be something with the load you're using.
 
#3 ·
Jason,

Welcome to ShootersForum! As a wise man used to say, "Rules are simple, be nice and join in."

You mention that you've shot your 300 RUM "a fair amount". How many rounds, roughly, have been through the gun? It sounds to me like you're still in the break-in phase and after a couple hundred rounds (potentially less, if you follow a break-in routine) you will probably see your groups settle down and be more predictable, from a cold barrel. BB710 could be right, as well, although bedding problems usually go the other direction, with groups opening up when the barrel gets hot.

The other possibility is that you're a little "flinchy" until you've put a few rounds down the tube and remind yourself that the thing isn't going to bash your brains out with recoil? I'm just sayin'... :)

Two things I would do, if I were you:

1) Shoot 1 round, clean the gun using a bore guide and brass brush/patches until no copper fouling shows. Repeat until 10 passes with brush and 2 patches do the job. Shoot 5 rounds, clean the gun....etc. I never shoot more than 20 rounds w/o cleaning as described above. In my personal experience this results in improved accuracy and MUCH easier cleaning. I also know my barrel is being kept clean, hopefully extending barrel life. (NOTE: I have used this technique on brand new, and very OLD, barrels, improving accuracy/cleaning on both! Some say it's hogwash, YMMV, n' all that. :) )

2) Whether or not you choose to try the above break-in period, shoot 1 round to foul the bore. Wait 10 minutes. Fire 1 round, wait another 10 minutes. (If at a public range, this is usually one or two rounds per session.) Do this 5 times and see what your group looks like. This is far more meaningful than how tight your 3rd or 4th, 5-shot group of the day is, from a gun that is thoroughly warmed up.

Yes, both of these steps take up a lot of time, but in my experience, it's worth it. If you're going to shoot your gun enough to do all of the above, I would recommend a Lead Sled, or other recoil-reducing device. No sense beating yourself about while getting your gun ready for season. Breaking your gun in this way, you really learn the rifle and give it (and yourself) the best chance possible to be accurate. After this process is done, cleaning is much faster and you send far fewer rounds downrange, because you know when the gun is ready. In fact, it can be down-right disappointing to go through this process, get the kinks worked out of the gun, and then find that you hardly need to shoot it anymore because it's all dialed in. This process frequently builds a confidence in your gun that you just can't get from shooting half a box of shells before season, each year.

I learned all of this from an old-timer who probably forgot more about accurate shooting than I'll ever know. If you saw the groups this guy made, on a daily basis, you'd know why I paid attention to what he said. His 100-yard targets were 3X5 cards with postage stamps stuck on them. I never saw a single time when he missed a stamp. His name was Al and I hope he is resting comfortably.
 
#4 ·
I agree this could be a fouling issue and that you should know where your cold shots place. A lot of barrels don't settle until they are fouled. I would say it is common for the first two or three shots not to be in the same group, but sometimes you get a rifle that takes a dozen rounds to settle.

I would alter the good procedure suggested above by putting up three targets and shooting one round into each of the three, always in the same order, before cleaning. Then clean, then repeat. Clean and repeat until each target contains your usual group count. This is to simulate being in the field and making one clean barrel shot and two follow-ups that we hope you won't need. If you get three acceptable groups, then the gun's barrel time is changing as it fouls, so the bullet exits at different points in the barrel's deflection under recoil. You want to find the center of each group so you know how much it shifts as the fouling accumulates so you may compensate in the field with small hold-offs.

Several things may be done to improve on the above situation. One is to try to develop a load range that isn't very sensitive to small shifts in barrel time. Dan Newberry's site details a systematic approach to doing this. Also, you may want to re-fire the three tightest sequential Newberry loads in similar weather to your actually expected hunting conditions to make sure the temperature doesn't move them significantly.

Another thing you can do is to make sure the gun is bedded to avoid any stock contact with the barrel. Just check that a dollar bill slides freely between the stock and barrel regardless of the barrel being warm or cold. If you use a sling in field positions, make sure that tension on the stock doesn't change this.

A third possibility is to add a barrel tuner, though adding weight to a hunting rifle doesn't much appeal to me.

I have more recently taken to cleaning with Bore Tech Elimenator. I've tried every bore cleaner made, and it is the best solvent type. Read the reviews at Midway if you want to see what other cleaners it's been compared to. Essentially odorless, non-toxic, water-based and petroleum distillate-free, and the fastest reacting copper removal chemistry made. It is also available fröm Sinclair International (800-717-8211) as are the bore guides. I recommend using both.

With the Eliminator you won't need to use a brush. Just push a couple of wet patches through and let it sit 5 minutes and push through a couple of more. Wait another minute or two and push through a dry patch to make sure nothing still comes out blue. That will likely do it unless your barrel fouls extremely, in which case you may wish to consider firelapping it? Don't use a brass jag with Eliminator, as it attacks copper alloys so fast the brass will turn the patch blue before it gets through the bore and make you think you still have copper in the bore. Use a plastic Hoppe's jag or a nickel plated jag with it like the ones Midway has.
 
#10 ·
I have more recently taken to cleaning with Bore Tech Elimenator. I've tried every bore cleaner made, and it is the best solvent type. Read the reviews at Midway if you want to see what other cleaners it's been compared to. Essentially odorless, non-toxic, water-based and petroleum distillate-free, and the fastest reacting copper removal chemistry made. It is also available fröm Sinclair International (800-717-8211) as are the bore guides. I recommend using both.

With the Eliminator you won't need to use a brush. Just push a couple of wet patches through and let it sit 5 minutes and push through a couple of more. Wait another minute or two and push through a dry patch to make sure nothing still comes out blue. That will likely do it unless your barrel fouls extremely, in which case you may wish to consider firelapping it? Don't use a brass jag with Eliminator, as it attacks copper alloys so fast the brass will turn the patch blue before it gets through the bore and make you think you still have copper in the bore. Use a plastic Hoppe's jag or a nickel plated jag with it like the ones Midway has.
I've really thought of giving Eliminator a try, I normally use Wipe Out and/or Sweets for copper, how's it compare IYO, sounds like it's better then either?
 
#5 ·
Actually, it probably isn't you if you are used to shooting a fair size round off the bags. And, not all M700's are equal.

A case in point is my current collection. My CDL Whelen came out of the box shooting MOA with Factory 250's. Cleaning up the trigger a bit, it consistantly shoots sub MOA with everything from 200-250gr, with four different powders. My 7-08 Mtn Rifle shot so bad I almost cried the first trip out. I installed a Timney, as the version I had was one of the non-adjustable versions, with about a 10lb pull. Then I bedded the recoil lug. I was down to about 1.5" for three shots. It was stringing vertically, so I free floated the barrel, got worse. Bedded the front 4", and it's down to .75 MOA. I stopped playing with my 7mm Mag after a trigger adjustment and bedding the recoil lug. It's a 1"/5 shot tool with hunting weight bullets from 139-162gr with IMR 7828/R22/MR3100, but outa' the box it was barely a 2" rifle.

Your story is odd though. I'm pretty sure I've been through 50 high power rifles, maye more, and I've had a couple that shot the same hot or cold, but never one that shot better as it heated up.

One thing I might try is a different bullet. My .30 Magnum experience stops at the .300 Weatherby level, and even that pokey old magnum needs a pretty good bullet at close range. A 180gr Hornady or Sierra is not a lot of money, but they tend to be more forgiving, and might be a way to see if it's just the bullet. And, a change in powder might cure the problem. Some barrel/bullet combinations are just not compatable.
 
#6 ·
Gentlemen,

I appreciate all of the great information thus far. I think all of you are pointing me in the right direction. I think that I am going to start by making sure that the barrel is properly broken in as described. I do clean the barrel but only after 20 to 25 rounds which with this gun is a typical shooting session. Anything more that that with out a lead sled as suggested I feel is a waste of time and ammo. The barrel get hot quick so I let the barrel cool a little between five shot groups.

I am also going to set up three targets as unclenick suggest to see where the gun groups on the first three shots out of a cold clean barrel. I think that this is a great idea seeing that I am using this gun to hunt and first shot is the one that counts. (hopefully I wont need those follow ups)

I did pick up some Hornady 180 grain interlocks and some H4831 to try and see if that helps. I have never tried to bed a rifle and not sure if I want to try that at this point in the game.

Thanks Again!
 
#7 ·
Jales,

The problem with only cleaning a brand new barrel every 20 to 25 rounds is that any slight imperfections in the bore/rifling become sufficiently fouled with copper that they are "protected" from being gradually smoothed out by subsequent shots. I'm not suggesting there are huge scratches or burrs to be lapped smooth, but breaking in a barrel as described above just helps the barrel settle in so it can do its best work.
 
#8 ·
I've got one rifle that will throw the first shot out of a cold barrel 4" - 6" high at 100 yards. Doesn't matter if it's clean or dirty, does it every time. It's been lapped and bedding tinkered with..... have run out of ideas. Thinking of pulling the barrel and sending to one of the cryo places to have it stress-relieved.

So yeah, that kind of stuff can happen. Uncommon but it does.
 
#14 ·
I've got one rifle that will throw the first shot out of a cold barrel 4" - 6" high at 100 yards. Doesn't matter if it's clean or dirty, does it every time. It's been lapped and bedding tinkered with..... have run out of ideas. Thinking of pulling the barrel and sending to one of the cryo places to have it stress-relieved.

So yeah, that kind of stuff can happen. Uncommon but it does.
Let me know how that works out. I have one that shoots a little high cold as well. I need to test it some more to determine why. It is glass pillar bedded and very accurate once warmed up.

As far as the .300 RUM guy, he should get a round that is a lil less efficicent. Perhaps a .30-378:)
 
#9 ·
Your problem could be as simple as the round you are shooting is not "in tune" with the gun from a cold bore. As the gun heats up your rounds will gain velocity and sometime become tuned to the natural harmonics of the rifle. Another thing to consider is seating depth of your handloads. The model 700's tend to have a lot of room to play with. Sometimes a simple change in this area can dramatically increase accuracy. Also, I have seen where a short seating depth (or leaving a jump) can cause heavy fouling in the chamber. The only thing I can really tell you is to experiment. Make one change at a time and see what works. The previous suggestions are also great. You generally can't hurt a gun from a good custom bedding job and doing a good cleaning of the gun with different solvents can't hurt either. An experiment to find out if it's fouling or heat issues would be to shoot until the groups drop is size as you have stated. Set the gun aside for an hour, shoot something else. Then go back to the gun when it's cool, but still fouled. If it still shoots good it's fouling, if it's back to 2-2.5" groups your problem is heat related and most likely needs a good bedding job.
 
#11 · (Edited)
I've tried about every gun cleaner ever made. I should take a picture of the cleaner collection shelf sometime. It's like a rogue's gallery with a lot of half-used bottles of what seemed to be best at the time, only to be bumped by something better. I won't even try to name them all. The solvents I am now using are Eliminator for most general cleaning (just too much faster and easier than almost anything else), Gunzilla for applications where a hard carbon build-up has occurred (it's exceptional at carbon cake softening if left overnight, and cleans moly out the same way), Sharpshoot-R's Wipe Out No-Lead for leading build-up only, and Ed's Red for mass quantities where needed (submersion of a torn-down handgun, etc.). I also have Kroil and Iosso Bore Cleaner (mild abrasive like JB Bore Compound).

If you go through the Eliminator reviews on Midway, you'll see the others trying it have also tried about everything else ever made and have all given it 5 stars. It's just a better mousetrap. Others that claim to be odorless are usually low odor. TM for example, is called odorless by some reviewers, but the ammonia in it, even though far less than Sweet's or Montana X-treme have, can still clear my sinuses. The Bore Tech products and Iosso Bore Cleaner (paste in a tube) are the only ones my wife can't tell I've opened about half a microsecond after I've wet the first patch.

jales,

The Iosso product reminds me: If you get some Iosso Bore Cleaner or JB Bore Compound, or Remington 40X (this product keeps getting renamed and repackaged, but is a tall thin yellow or white plastic bottle with a snap-on cap and a thick brown liquid inside), these are all mild abrasives for cleaning that also polish the bore surface. They don't remove enough metal to cause dimensional issues, but they can help reduce fouling. You get an undersized (.270, in this case) nylon bore brush and wrap a couple of patches over it. Apply the abrasive cleaner to it and go in through the bore guide. When you feel it pack into the bore, stroke back and forth a couple of inches in the throat area two or three times, then start going forward about three inches then back two over and over. You should have 20-30 short strokes by the time you get the patches to the muzzle. If you do that once each cleaning cycle followed by a wet then a dry patch to clear out the mild abrasive and black polished metal, the gun will grab less copper after you are through with your test series. What the heck, it's just more time and effort.
 
#23 ·
Some thoughts on barrel prep & loads.

I also have Kroil and Iosso Bore Cleaner (mild abrasive like JB weld).
I'm hoping this was a typo!: JB Weld might create an interesting problem. I'm sure you meant JB Bore Compound....

unclenick said:
The Bore Tech products and Iosso Bore Cleaner (paste in a tube) are the only ones my wife can't tell I've opened about half a microsecond after I've wet the first patch.
I'd agree. Bore-=Tech and Iosso are good. I use Sweets on one timers,, but the electrochemical system by, who is it, with the rod electrode, works like a charm. On the worst guns, after about 3 hours, you pull out that rod and it's covered with copper sulphate crystals. (I think)

I had a 340 Weatherby, Mk V that shot under 1" groups (it was one of the sauer-built models...) but over about 4 years the accuracy got worse and worse. It would only shoot 3inch groups no matter what I did. The local know-it-alls at the range told me, in no uncertain terms, that "them Weatherbys jist shoot out their barrels real fast-like, and soon enough yah gotta throw 'em out!"

Then I discovered Sweet's 7.62, via an old gunsmith (soon I'll be an old gunsmith... Hmmm...) and had at it. took me about three days of gooping the bore and timing it for about 20 - 30 minutes and then patching it. Lots of blue patches, but finally, it cleaned up. I hurried to the range and guess hat? The thing shot into 3/4 inch all day long! Now I always keep my barrels de-copperized. (Is that a word?)


unclenick said:
The Iosso product reminds me: If you get some Iosso Bore Cleaner or JB Bore Compound,

..... If you do that once each cleaning cycle followed by a wet then a dry patch to clear out the mild abrasive and black polished metal, the gun will grab less copper after you are through with your test series. What the heck, it's just more time and effort.
All good stuff. Time consuming, but spending time with a good and trusted gun beats spending time with... well... lots of things.

I'd suspect bedding, but you might want to consult someone who has done it a few times. There's some good and bad tips, and I've had to redo many of them where guys have gotten the stuff into the wrong places. It can actually make things worse, or show no improvement, while properly done, it will almost always improve things. Acra-Glass from Brownell's is just OK; some of the stronger, harder epoxys do a much better job.

You may have to fiddle with forend pressure pads as well, especially if your barrel is sorta thin and whippy! Those hyper mags do induce a lot of vibration and heat (3 rounds through them will really heat up the bbl. Remember: we're making about 65,000 lb/in sq. wow!)

You may also find that rifle-specific reload development will yield big results. Those good loads may be slightly less than some book's listed full charge, "let-er-rip!!!", Chernobylizing-type loads, but the elk or caribou really won't know the diff out @ 479.6 yards. and your shoulder, and the gun, will thank you! Those extra "37 fps" can essentially destroy shot-to-shot accuracy, and I've found that, in the case of my .340, when I reduced the loads of the 225 Spire Points by about 40 fps it suddenly started grouping in the sub 1" level, previously shooting into about 1.25" reliably. That slight reduction in pressure and the vibrational dynamics had it shooting from a more stable point in the barrel's dynamics.

A properly cleaned and then seasoned barrel will stay cleaner, run cooler (less friction) and shoot faster with lower powder loads than one that has not been properly broken in. There are folks who say it's absolutely not necessary; just ask the bench-resters. Not a one of them would ever NOT break in a barrel. It's also never too late; the bullets running down a down-to-the-metal-cleaned bore will swage the micro-surfaces smoother than if it's never cleaned, or you let it get chemically pitted by not cleaning properly.

Keep us in the loop!
 
#12 ·
Sendero

I am also having some accuracy issues with a fairly new 300rum Sendero. It started last year when I bought the gun and I have not had time to work on it due to my career workload lately. I will however be on it hot and heavy in the near future and will be looking for advice from our web gurus as well. Good luck Jales and I'll be watching.
 
#13 · (Edited)
I will tell you that the best powder I have found for the .300 Rem. Ultra mag, shooting a 165 grain bullet is H-1000. Now for the 180 grn bullet it has been the RL-22 by far the most accurate powder in at least 5 of the same caliber rifles, 2 being model 70 Winchesters. The RL-25 and MAGNUM have done very well in the accuracy department using 200 grn bullets. I like that Nosler Accubond for long range shooting. I handload for my rifle and 2 others that I mentioned and worked up the loads for all 3 at my bench.
 
#15 ·
jales, I had the same rifle in 700CDL. It would shoot 2-2.5 groups until I floated the barrel and bedded the recoil lug. Then it was a different beast. Groupos went down to 1" with no difference between a hot, cold, dirty or clean barrel. I was using the same bullet and powder you are but I ended up using IMR7828 instead. I "traded" that rifle for my Sendero SFII. Oddly enough it likes the 'zact same load!!

Now I'm playing with 200 grain Accubonds and RL25.

RJ
 
#16 ·
Once again I really do appreciate all of the advice. I got to shoot a little last night and at the moment I am going through the break in procedure described by broom_jm. Things seem like they are improving, one thing that I have noticed is that I do think that the 300 RUM copper fouls pretty quickly and I am not so sure that i was getting it all out with my typical cleaning. I have been trying some different solvents, and as of tonight just ordered some Bore Tech Eliminator as suggested as suggested by unclenick. I read the reviews and I don't think that a guy can go wrong with this stuff. I also picked up a bore snake, I thought I would give that a try for on the range cleaning between shots. I will let you all know how things progress as I plan to be out shooting again tomorrow.

Also I would suggest to any reading this to check out the Dan Newberry's Site ( if you haven't already) that unclenick has listed. That is some pretty neat stuff, I will defiantly play around with that at some point.

Best Regards
 
#18 ·
Jales,

It surprises most guys just how much copper fouling their gun has, when they set out to clean their gun properly, for the first time. I am glad this seems to be helping and really look forward to hearing more about how this turns out. If nothing else, you will get a lot of time with your gun this way and be 100% comfortable with it, come season.
 
#19 ·
Well Gents, I think that I am Making some progress. I have been taking extra care in cleaning the barrel which has defiantly helped. My groups from a cold barrel are down to 1.5" to 1.75". I am still getting much better groups from a hot barrel, out of a cold barrel the group is basically centered around the bull, out of a hot barrel the group size comes into an inch and drifts 1.5" right and 1.5" high. So I think that I do need to take a look at the Bedding. I am going to keep going with the break in the mean time.

Thanks for the continuing advice.
 
#20 ·
You're very much on-track and I'm glad to hear things are getting better. Soon enough you'll have the barrel broken in and it will become more predictable in what loads it likes. I think you're smart to look at the how the action is bedded now, as that will probably correct the issue of your group drifting high n' right. Still, before you go out to hunt with it, foul the bore with a shot or two, then let it cool completely in-between 5 cold-bore shots. Use this to adjust your point of aim so you're hitting about 2" high at 100 and you'll be all set.
 
#21 ·
Well my shooting at this point has remained about the same over the past few sessions. I am getting ready to look at the bedding but I don't have any experience with it other than what I have read, would you recommend any particular bedding kits? Should I think about pillar Bedding?

Also I have tried to run a dollar bill between the stock and the barrel and it stops about an inch in. I have read that Remington puts a pressure pad in the for end of the stock and I am not sure if at this point I should remove it to completely free float the barrel. If I did remove it and it does not work then how do I put it back?
 
#22 ·
Jales,

Every 700 I have ever had has benefited in accuracy from removing any pressure pads that remington installed. The gun may become more picky on the loads that it likes but when you do find the one it likes the groups will be considerably tighter. I would suggest that, because you don't have any experience with bedding a gun that you take it to a local gunsmith(one with a good reputation) and discuss with him what you want to do. Pillar bedding is an option but if you're going to go that route you may just want to buy a new stock that comes with pillar bedding or a full bedding block. Having done some extensive work with 700's i'd say that you could probably get away with the local smith bedding the action and floating the barrel.
 
#24 · (Edited)
Yup, I meant JB Bore compound. Sometimes my fingers take off ahead of my brain. I'll go back and fix it.

You're thinking of the Outer's Foul Out. It actually plates the copper to a central stainless rod. It hangs there like copper dust and you wipe it off. The patent has now expired and you can make your own. There is a simple design I did for Father Frog's site for a .3V regulated home brew version, but it uses Radio Shack part numbers that may no longer be valid. You can look. I don't recommend the listed cleaning solution. I would either buy the Outer's solution for copper or make it's equivalent. I'll have to rework that design for more current parts and include a solution recipe.

Break-in is sure controversial. I concluded a long time ago that if break-in is your only objective, you should just clean every round until you are done. The business of creeping up on three, then five rounds between cleanings just lets more copper accumulate on the spots that need burnishing most. With the JB or Iosso bore cleaners, you can do more in 20 rounds, cleaning after every shot, than most break-in procedures can do in 100 rounds if they are ever able to equal it at all. So, it saves on barrel life to do it every round. I recommended every third round earlier because the objective is not just break-in, but learning where the rifle puts three in a row, starting from a clean barrel. He may wind up firing 60 instead of 20 to get broken in equally, but he'll have 10 shot groups that give a fair average location for change in POI as fouling and heat accumulate.

Speaking of barrel life, Scottish Ballistician Geoffry Kolbe suggests that any rifle fired at over about 58,000 psi experiences greatly accelerated throat and bore wear. I generally try to hold my rifles down to that, going to a bigger capacity case rather than higher pressure when I need more velocity. As to finding sweet spots, it varies with the powder as to what velocity achieves what barrel time. For a given velocity, faster powders do more of the accelerating nearer the breech end of the bore, so the bullet is moving fast down most of the barrel and has a short barrel time. A slow powder producing the same velocity has a lower peak pressure and more sustained pressure further down the tube, so more of the acceleration takes place further down the tube. That later acceleration means the barrel time gets longer. So, if your barrel has a specific barrel time that meets a vibrational sweet spot, altering powders can tune to it at different pressures.

As I mentioned before, but will mention again, because it's effective, Dan Newberry has a systematic method of finding these sweet spot loads.
 
#25 · (Edited)
Now for what it is worth, I always free float the barrel and rebed the action on all my hunting rifles. I just got done with a set of Marlin .22 mags that would NOT shoot worth a hoot said the owners. One in particular shot 2 inches high at 50 yards with a cold barrel 1st shot. Then 5 shot groups were around 2.75" inches at 75 yards. The other Marlin .22 mag shot left of center on first shot (2.5 inches) and held a 2.5 to 3 inch group from the bench. Now both rifles sported a Bushnell Trophy 4 x 12 scope on top!

Once I removed the wood from the stock with my Dremel Tool, I glassed bedded the actions of those rifles. I built up the area where the lug was with glass bedding (widened the lug 1/2 each side of the screw area that holds the stock in place. Wax paper over the glassed area and set the barrel and action back in place. Once dried it was time for the shooting range. We tried no less than 6 types of various .22mag ammo in 30 grn, 34 grn, and 40 grn bullet weights.

The same process can be used on any rifle regardless of caliber. I also cleaned the barrel twice before the range trip, using Bore Scrubber and Copper Solvent. Now at the range I fired 1 shot to clear the barrel out, then settled down to shoot a 5 shot group with said ammo. My worse group was 1.3 inches at 75 yards! Two types of ammo produced a 5 shot group of 3/4 inches and 1 CCI type ammo using 30 grn bullet shot a 5 shot group of 1/2 inch at 75 yards. The other rifle best group was .645 at 75 yards. A little tuning and hands on prepping can make a lot of difference on the performance of your rifle.:)
 
#26 ·
Well at this point I am not making any more real progress. Last night I free floated the barrel. I only had enough time to put 5 rounds trough a clean cold barrel with no improvement. I didn't have time to put another 5 rounds through a hot fouled barrel. However I hope to shoot tomorrow and get a better feel for it. (with factory loads)

I think that I am having some issues with my hand load. I started at the recommended starting load and gradually worked up to the max suggested load for the powder that I am using (H1000), with no pressure signs. However I started with new brass and now that it is all once fired I went through all the case prep and prepared to load again. When I primed the brass with an RCBS hand priming tool there was not as near as much resistance as there was when it was new. I have not had any back out or move but they do seem looser then what I think that they should. I plan on decapping the five round I shot tonight to see if there is anymore change in the primer pocket. When I was working up the load I paid close attention to the primers and did not really see any difference from the starting load to the max load. I am loading by the book at this point in regards to COL and charge weight and such. I dont think that that my decapping pin is bottoming out and "flaring out" the brass, but i didn't get a chance to check yet.

At this point I have not glass bedded the action as I have a little less than a month and not sure how quickly the smith can get it back to me.

Thanks for the continuing advice
Jason
 
#27 ·
Jales send me a PM on your loads and what you have done so far with your .300 Ultra mag. Perhaps I and another fellow can shed a little light on your problem. We both shoot this caliber, mine is a model 70 Winchester and his is a Remington. We both use Nosler Accubond bullets but have also used Sierra and Hornady bullets for target shooting.;)
 
#28 ·
I think we got it nailed...

Well I leave for my elk/mule deer hunt in a week and a half so I thought I would give you an update. I think that I have got the gun and the load figured out. I went through a thorough break in, free floated the barrel, and my hunting load ended up being 180gr Hornady Interlock over 93.4 gr over H1000 with Federal 215 primers. I am shooting approx 3/4 in five shot groups (off of sand bags) out of a cold bore after a couple of foulers. Unbelievable improvement from where I first started. I would post some pics of the before and after results but I don't see where to do that.

Thanks again for all of the input. Learned a lot about this particular rifle.

I will let you know how the hunt goes.
 
#29 ·
Well I leave for my elk/mule deer hunt in a week and a half so I thought I would give you an update. I think that I have got the gun and the load figured out. I went through a thorough break in, free floated the barrel, and my hunting load ended up being 180gr Hornady Interlock over 93.4 gr over H1000 with Federal 215 primers. I am shooting approx 3/4 in five shot groups (off of sand bags) out of a cold bore after a couple of foulers. Unbelievable improvement from where I first started. I would post some pics of the before and after results but I don't see where to do that.

Thanks again for all of the input. Learned a lot about this particular rifle.

I will let you know how the hunt goes.
Jason,

Kudos to you on being persistent and taking the steps to not only figure out the problems you started with, but learning your gun quite well, in the process! Sub-MOA groups out of a big boomer like the 300RUM means you are doing everything right, from your handloads to your shooting form. Those 180gr Interlocks should do a great job, too. I hope your combo hunt is just as successful as the work you put into getting your gun to shoot the way you expected! :)
 
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