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  #1  
Old 02-05-2011, 09:57 AM
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Bullet Seating Depth Issues


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I am fairly new at handloading. Have done a couple hundred rounds so far. I have been seating bullets either to the cannelure or to match factory COAL if no cannelure. Today I decided to take the next step and determine the best COAL for each of my rifles with the bullets I am using. Worked fine in my .30-06. The bullet stopped about 3/32 short of the cannelure (haven't gone back out to the shop to get my calipers so bear with me). Not so good with either my .444 handi-rifle or my .243 savage 110. I used one bullet in the .444 (265gr. Hornady FTX) and two bullets in the .243 (95 gr. SST and 100 gr. Horn BTSP). All of these stopped at least 1/4" short of the cannelure.

My question is whether this is deep enough? Should I stick with seating to the cannelure? Is there any risk to not seating deep enough?
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  #2  
Old 02-05-2011, 10:18 AM
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I have started seating my bullets .10 in off of the lands, regardless of cannelure location and have had good success with accuracy and no issues with feeding from the magazine so far. On the same token, I would be hesitant to leave too much of the bullet out of the neck, as you may not have enough neck tension for consistent pressures or stability to control runout.

Just my .02
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  #3  
Old 02-05-2011, 10:24 AM
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As long as each respective bullet is clear of the lands when you close the chamber, then yes, you are seating them deep enough into the case mouth. If the action is as at all difficult to close, be sure the bullets are not engaging the lands by applying black magic marker to the tip (past the ogive) of a new bullet, before attempting to chamber it. If no marks are present to indicate the bullet was into the rifling, then you're safe.

Now, presuming this length will cycle in any of your repeating actions, you'll want to use this as a starting point for finding your most accurate load. Seat 5 bullets each, .005" deeper into the case, firing groups to see where your sweet spot is. As a general rule, I have found this to be somewhere between .010" and .030" off the lands, but each gun/bullet is different. I rarely seat a bullet less than .010 off because I don't want to run into any issues with my gun cycling, or the action closing, properly.

I will also say that I'm surprised the 265gr FTX bullet is seating that long...I would have guessed it would seat past the cannelure (deeper), especially if you're using full-length cases. Hornady's load recommendation calls for a case that is shortened a bit, but keep in mind; that is to allow for proper cycling in lever-action rifles. Still, this suggests your 444 chamber is rather long, or you might say it has a lot of freebore. It's not always as easy to detect when a bullet is hitting the lands, while closing a break-action rifle; be especially sure you're clear with this gun/bullet.
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  #4  
Old 02-05-2011, 11:04 AM
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I always let the magazine length determine the seating depth of my cartridges. Lots of these rifles are customized military firearms, so the magazines can be quite short. As an example, the lands on a Shilen barrel installed on a Brazilian Mauser M1908 action (originally a 7mm Mauser) and chambered for 6.5-06 is some .095" off the lands when seated to clear the magazine. I just consider this extra jump an advantage to keep pressures down a bit and compensate by juggling the bullet type/weight and powders/charge weights for best accuracy.
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  #5  
Old 02-05-2011, 01:02 PM
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i seat the bullet for the magazine as long as i can and still cycle in my bolt my 22 250 has a long box for that a go off the lands (very short jump) the cannelure does not mean anything to me as far as seating depth
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  #6  
Old 02-06-2011, 06:10 AM
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Like Kdub, I find that magazine length limits how far out you can seat bullets. For a varmint/target rifle, you can seat bullets out to far to work through the magazine, and that may work OK for your application. For hunting, not so much. . .
One of the cartridges you're working with is 444 Marlin, if I''m reading right. If you're using a tubular magazine rifle, you probably should seat bullets to the cannelure, and crimp them, to keep the magazine spring from pushing the bullet deeper into the case. Often you have to seat to the cannelure, anyway, for reliable feeding.
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  #7  
Old 02-06-2011, 07:50 PM
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One of the cartridges you're working with is 444 Marlin, if I''m reading right. If you're using a tubular magazine rifle, you probably should seat bullets to the cannelure, and crimp them, to keep the magazine spring from pushing the bullet deeper into the case. Often you have to seat to the cannelure, anyway, for reliable feeding.
Reply With Quote i agree i was just thinking of bolt guns sorry for the bad info
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  #8  
Old 02-07-2011, 06:48 AM
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His 444 Marlin is a Handi-rifle (single-shot, break action), so there is no magazine. Cartridge OAL is determined by the chamber/throat in the gun.
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  #9  
Old 02-09-2011, 05:20 PM
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Thanks for the info, guys. I need to check magazine lengths, as I didn't think of that before
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  #10  
Old 02-09-2011, 05:55 PM
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Letting the magazine determine the seating depth, NO WAY IN H***.

On some rifles magazines, yes, because there is no way you could get the bullet to the lands and it still feed from the magazine but that's not true with all. A prime example is the Tikka's. I think all the USA imported Tikka's are all long actions, even in the short action calibers, like the 22-250 and 243. I can jam the lands in both the one's I have and still have bunches of room left in the mazagine. I have a couple of other rifles that when against the lands, there is still plenty of room in the magazine.
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  #11  
Old 02-09-2011, 06:22 PM
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Interesting thread, in that just this past weekend, I did a little experiment with my Ruger Hawkeye .308. I believe SAAMI standard for maximum OAL for a .308 is 2.81 and most manuals seem to round that to just 2.8. First off, I seated a bullet way out in a resized but unprimed case and started trying to put it in the magazine. I found that the maximum length the magazine would take and allow cycling out of it was 2.89. With both a 165 Nosler Ballistic Tip and a 168 Sierra Matchking at that OAL, neither bullet was touching the lands. So I loaded up a 5 rounds for every 15 thousanths from 2.890 down to 2.800 (based on how many bullets I had of each). At the range, I shot for groups at 100 yards. I found that with the 165 Noslers, I shot a .40 group for the 2.860 length and with the Sierras, I shot a .50 group for the 2.815 length. I know, only one test and one group for each length. But it gives me a starting point for further work. The Noslers have always shot better in my gun than the Sierras. The Nosler Ballistic Tip is longer than the Sierra Matchking,so I figure the jump to the lands is probably about the same for both even though the OAL for the Sierra is shorter. I will just have to buy some more bullets to do further experimenting but I am pretty pleased with my initial results.
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  #12  
Old 02-10-2011, 05:38 AM
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+1 to what BKeith said...and the man KNOWS accurate rifles.

If you want the best accuracy, you find the maximum OAL your chamber/throat will allow, then work back in small increments. If the resulting cartridge OAL won't fit in your magazine, then you start with a length that will fit in the magazine, and work back from there. In practice, the two methods are rarely mutually exclusive.

I guess if I wasn't all that interested in getting the best accuracy possible and really just wanted something that would feed from the magazine of my gun, I'd start there. I might be a bit biased since many of my guns are single-shots with no magazine length to consider. In the bolt-action rifles I have, the most accurate loads have fit in the mag...although some, just barely!
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  #13  
Old 02-10-2011, 03:27 PM
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I use a bullet comparator to measure the exact distance to the lands with every bullet I load. It gives you the actual distance to the lands with each bullet. I then work back from there using the magazine max or the distance to the lands which ever is the shorter value.

With some bullets like the Barnes solid copper They suggest you stay at least .070 of the lands and I have found this to be true you will get very high peak pressures going any closer even with lower volume powder loads.

Kevin
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  #14  
Old 02-10-2011, 08:26 PM
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After reading and trying a few different methods for figuring maximum COAL, here's what I like best:
- cut a wooden dowel of a diameter that will fit easily in the bore - about 24" or so;
- cut another about 12" or so;
- hot glue a bullet of your choice onto the end of the shorter dowel;
- close the bolt (or action), and insert the longer dowel into the bore from the muzzle, until it stops on the bolt face;
- using a pin or exacto knife, mark the dowel right at the exact end of the muzzle;
- pull the long dowel out a few inches and now open the bolt (remove if necessary) and insert the short dowel into the breech - carefully so as not to break the bullet/glue bond - push it in until the bullet is tight against the lands. Hold it there with one hand;
- push the long dowel back into the muzzle until it contacts the bullet;
- with pin or exacto blade mark the dowel where the exact end of the muzzle is;
- the measurement between these two lines on the long dowel is the maximum COAL for that particular brand and type of bullet;
- now you can load them shorter to fit the magazine or up to about .010" shorter than that maximum COAL.

Some rifles and load combinations like the bullet close to the lands, others like a little bit of a jump, and some it's best to just make them to fit the magazine as was said.
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Last edited by StretchNM; 02-10-2011 at 08:29 PM.
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  #15  
Old 02-13-2011, 10:14 AM
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Quote:
Originally Posted by BKeith View Post
Letting the magazine determine the seating depth, NO WAY IN H***.

On some rifles magazines, yes, because there is no way you could get the bullet to the lands and it still feed from the magazine but that's not true with all. A prime example is the Tikka's. I think all the USA imported Tikka's are all long actions, even in the short action calibers, like the 22-250 and 243. I can jam the lands in both the one's I have and still have bunches of room left in the mazagine. I have a couple of other rifles that when against the lands, there is still plenty of room in the magazine.
I took the earlier comments about magazine length as just a warning to make sure that the rounds would fit in the magazine and feed properly rather than actually using the magazine to determine COAL. I took each of the dummy rounds that I used to establish COAL to reach the lands and checked them in the bolt guns, and each worked fine, so I think I am good to go.

Should I start with the bullet closer to the lands (.01 is what I am thinking) and move back or vice versa? Or does it matter?
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  #16  
Old 02-13-2011, 11:53 AM
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It doesn't matter, but that's probably easiest. How deeply seated will shoot most accurately appears to be dependent on bullet and chamber shape. Some of the short round nose bullets like to be pretty close. Berger says its long secant ogive VLD shapes sometimes want to be as much as 0.165" off the land in their experiments.

Writing in the Precision Shooting Reloading Guide, Dave Milosovich tells of how, in switching bullets one day for his 220 Swift, he turned his micrometer seater thimble the wrong way and wound up with the bullets deeper than intended. 0.050" off the lands instead of 0.020". He had 20 round loaded before he realized the error, but decided to just to shoot them in practice rather than pulling and reseating. To his surprise these rounds shot better than any he'd previously loaded for the rifle. Where it had never before shot better than 3/8" at 100 yards, he got two groups 0.250 inch and two bugholes in the 1's from these 0.050" off-lands loads.

The issue seems to be how bypass gas flows around the bullet and whether it does this in a way that can help self-center the round or tends to tip it off to the side. Since start pressure is close to the same for a given bullet and seating depth regardless of the powder charge used, you can establish the best seating depth with a starting load light enough that even touching the lands doesn't create excessive pressure. 10% below a previously established maximum load with the same bullet is usually good enough for that. 10% reduction in powder charge lowers pressure about 20% at the peak, which is about how much touching the lands usually raises it. So, you can start at the lands and move back in 0.010" steps until you find a minimum light load group, then tweak the powder charge back up to shrink the group the rest of the way. That's the method Somchem used to use when they still offered load tuning as a service many years ago.

It is not unheard of to find more than one seating depth sweet spot. One out nearer the lands than normal magazine feed allows, and one when the bullet bearing surface is around one caliber into the case, though it may not be quite as tight. This is for tangent ogive spitzers. YMMV.
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Last edited by unclenick; 02-21-2011 at 09:56 AM. Reason: typo fix
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  #17  
Old 02-19-2011, 10:04 AM
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Unhappy

Check out 6mmBR for some discussions on bullet seating...several shooters have different seat depth "sweet" spots for the various cartridges.

In the same vein but concerning powder amounts check out Accurate Arms reloading section...the various cartridge testings show a variation in groups as the load increases(or decreases depending on how you look at it).

I'm guessing it all has to do with barrel harmonics...finding the null node but bullet seat or powder amounts which is a by product of velocity variance.

This game is worse than gol..f once you start getting more advanced the "pressures" start to mount up. and it is MUCH harder to get those groups to go anywhere but bigger...just like that ball cup...once the putts get longer the hole get smaller at a geometric rate. Hahahahaha

Luck
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Old 02-20-2011, 11:49 AM
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Quote:
Originally Posted by Sandman1 View Post
I took the earlier comments about magazine length as just a warning to make sure that the rounds would fit in the magazine and feed properly rather than actually using the magazine to determine COAL. I took each of the dummy rounds that I used to establish COAL to reach the lands and checked them in the bolt guns, and each worked fine, so I think I am good to go.

Should I start with the bullet closer to the lands (.01 is what I am thinking) and move back or vice versa? Or does it matter?

This should work, however be very careful that the extra length doesn't get stuck in the chamber. The reason being that if you should have to extract a round while hunting or shooting and the bullet gets stuck in the chamber and you should chamber and fire another round on top of it your barrel will likely burst and injure you quite badly. Perhaps you aren't loading to that extreme length, then you will have no problems. Just a precaution you should always be aware of.

Just as a quick example. I have a Kimber 1911 45acp. When I first got it I began loading some cast bullets for it at about 10 thou short of the recommended OAL. Every darned on of them would stick in the chamber. This is a really big problem in this kind of auto, as the powder will then settle down into the firing mechanism and make a big mess, especially hard or impossible to fix if you are in the field. This same thing can easily happen to ANY type of firearm.

Quote:
Originally Posted by unclenick View Post
It doesn't matter, but that's probably easiest. How deeply seated will shoot most accurately appears to be depended on bullet and chamber shape. Some of the short round nose bullets like to be pretty close. Berger says its long secant ogive VLD shapes sometimes want to be as much as 0.165" off the land in their experiments.

Writing in the Precision Shooting Reloading Guide, Dave Milosovich tells of how, in switching bullets one day for his 220 Swift, he turned his micrometer seater thimble the wrong way and wound up with the bullets deeper than intended. 0.050" off the lands instead of 0.020". He had 20 round loaded before he realized the error, but decided to just to shoot them in practice rather than pulling and reseating. To his surprise these rounds shot better than any he'd previously loaded for the rifle. Where it had never before shot better than 3/8" at 100 yards, he got two groups 0.250 inch and two bugholes in the 1's from these 0.050" off-lands loads.
Is it possible that he was loading the shells so long (excessive OAL) that he was having the bolt ste the OAL? I've seen this done, and if so, then each round will end up being a different OAL, and a sure cause of inaccuracy. Just my thoughts.
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Old 02-20-2011, 02:41 PM
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Jimbo,

What you are describing is called "soft-seating". It used to be a favorite benchrest technique until it was discovered you can usually get a little more accuracy by letting the bullet run up to the lands at least a little. Mid Thompkins still does it, but that's not for benchrest.

In Milosovich's case, I'm sure he knew exactly where the gun's throat was and had the gauges needed to peg it accurately. One drawback to soft seating is that if your case mouth is loose enough to allow it, the bullet usually sticks in the throat when you chamber, and if you have to remove a live round for a cease-fire or other matter, and forget to point the muzzle up first (which a lot of ranges no longer allow), you wind up with an action full of spilled powder. In other words, if you are soft-seating but don't realize it, sooner or later you get a rude surprise that tells you it's going on.

Take a look at the first post in this thread for an interesting read on seating distances off the lands. Berger used to think touching the lands was best, but now knows otherwise.
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  #20  
Old 02-20-2011, 03:01 PM
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Yeah, I never liked shooten the jam as the benchresters say. I always shot from 5-15 thous off the lands. I was afraid of dumping all that powder in the reciever and especially the trigger. Jewel 2oz triggers just don't work with any grit or dirt in them.

I've read that article before, but thanks for the reference.
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