Have a 7MM Rem Mag that appears to like a .100 jump in the bullet to the lands. Started closer to the lands and been playing with different loads but it seem's that the .100 area jump gets best accuracy. Some bullets like touching (ei. Berger) and I believe that Barnes has a bullet that they say must have a .050 jump. Common practice is in the .020 range. So the question how much jump is to much before you start causing damage to rifling or chamber etc? Bullet in use is Sierra matchking 168 gr. in a kimber 8400. Thinking about trying a different bullet what would be a good accurate hunting bullet in this caliber? Seen the Nosler accubond 160 gr. has a higher BC than the matchking, any input on the nosler? Thanks for the any input.
How far is to far from the lands?
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The 140gr Accubond in my 270 Winchester has been a real joy, both from the bench and in the field. You may find that each bullet likes a different seating depth, or that your gun consistently prefers the ogive to be "x" thousandths off. Like so many things in reloading, it really just depends. 
In my experience, it is a bit unusual to have to back off that far, to get good accuracy. The SMK isn't a hunting bullet, but give the Nos. Accubond a try and I bet you'll find it is nearly as accurate as the Sierra, and will give more reliable terminal performance.
In my experience, it is a bit unusual to have to back off that far, to get good accuracy. The SMK isn't a hunting bullet, but give the Nos. Accubond a try and I bet you'll find it is nearly as accurate as the Sierra, and will give more reliable terminal performance.
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Can't be answered, although I have never used a jump of .100 in anything. Broom-jm is right in that every rifle/load combination will have its own variables.
I would not use the MatchKing for hunting. My only "hunting" experience with them was when I tried using them in my .22-250 because they shot so well. Very erratic terminal performance, and I would not try big game hunting with them as a result.
I like Nosler bullets because I have used them for years now and get both very good accuracy and predictable terminal performance. Partitions, Ballistic tips, and Accubonds have all worked for me in various loads and calibers, and for different applications. I have come to prefer heavy for caliber bullets for hunting, so I would certainly recommend trying some160 grain Accubonds if they have attracted your interest. They will be much better hunting bullets than the MatchKings.
I would not use the MatchKing for hunting. My only "hunting" experience with them was when I tried using them in my .22-250 because they shot so well. Very erratic terminal performance, and I would not try big game hunting with them as a result.
I like Nosler bullets because I have used them for years now and get both very good accuracy and predictable terminal performance. Partitions, Ballistic tips, and Accubonds have all worked for me in various loads and calibers, and for different applications. I have come to prefer heavy for caliber bullets for hunting, so I would certainly recommend trying some160 grain Accubonds if they have attracted your interest. They will be much better hunting bullets than the MatchKings.
All my hunting rifles have the cartridge COAL and bullet seating depth determined by what feeds reliably through the magazine.
A new (to me) firearm gets the max COAL checked with dummy cartridges first, then checked as to maximum length that will feed from the magazine. In some cases, this amounts to a jump in excess of .050", but accuracy is always determined by bullet configuration, type and amount of powder and type of primer.
Roy Weatherby established long ago that long jumps don't necessarily affect accuracy and that it benefits by reducing chamber pressures. That's why his rifles always had very long leads.
A new (to me) firearm gets the max COAL checked with dummy cartridges first, then checked as to maximum length that will feed from the magazine. In some cases, this amounts to a jump in excess of .050", but accuracy is always determined by bullet configuration, type and amount of powder and type of primer.
Roy Weatherby established long ago that long jumps don't necessarily affect accuracy and that it benefits by reducing chamber pressures. That's why his rifles always had very long leads.
See, I've always come at the problem from the other side than the way Kdub does it. I seat the bullets very long with the seating die, slowly working my way in until the bullet is just off the lands. Then, I check the COAL and if it's short enough to cycle (it usually is) I work back in increments of 5-10 thousandths, until I find the sweet spot for accuracy. In most of my guns, the dimension from case rim to ogive is remarkably similar for what length gives the best accuracy. It is typically between .010" and .030" off the lands.
Roy had very long leades on his guns because he was running those babies HOT and he wanted to keep the pressures down and the velocity up! Accuracy is primarily a function of concentricity, presuming the gun is well-constructed in the first place. Get the case body, neck, and the bullet's center of mass lined up very well with the bore, especially as it transitions from the case neck to the throat of the barrel, and you're probably going to see very good accuracy. The reason seating close to the lands will frequently result in good accuracy is that the bullet is handed off very nicely from the round confines of the case neck to the throat of the rifling. Have your neck tension uneven, or those two dimensions even slightly misaligned, and accuracy goes out the window.
Roy had very long leades on his guns because he was running those babies HOT and he wanted to keep the pressures down and the velocity up! Accuracy is primarily a function of concentricity, presuming the gun is well-constructed in the first place. Get the case body, neck, and the bullet's center of mass lined up very well with the bore, especially as it transitions from the case neck to the throat of the barrel, and you're probably going to see very good accuracy. The reason seating close to the lands will frequently result in good accuracy is that the bullet is handed off very nicely from the round confines of the case neck to the throat of the rifling. Have your neck tension uneven, or those two dimensions even slightly misaligned, and accuracy goes out the window.
I double checked the distance to the lands matched the seating die mic and it was correct. Although none of the replies have indicated that a long jump is bad, I agree that it seems odd. Think starting over might be a good idea and adjust seating depth in .005 incraments instead of .010 might be the thing to do and see what happens. Maybe I missed the sweet spot.
Think I'm going to give the Nosler a try. Need a hunting bullet for this rifle and never tried Nosler before. (Only used the SMK to kill paper) Seems everybody is sold out of the 160 gr Accubond.
Think I'm going to give the Nosler a try. Need a hunting bullet for this rifle and never tried Nosler before. (Only used the SMK to kill paper) Seems everybody is sold out of the 160 gr Accubond.
The Nosler Partition is a fine hunting bullet - just don't expect tack driving accuracy as you would from the SMK. Used them for years until the Hornady SST came along. The NP's do pretty fair for grouping, but yet have to shoot sub-MOA or MOA with them in a variety of chamberings and calibers.
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"Have a 7MM Rem Mag that appears to like a .100 jump in the bullet to the lands."
If that's what it likes, it's just right. Not at all odd, what's odd is how many people think seating at or even into the lands is magic for accuracy. It is not, especially for factory sporters shooting hunting bullets.
Jump has no practical effect on throat errosion.
If that's what it likes, it's just right. Not at all odd, what's odd is how many people think seating at or even into the lands is magic for accuracy. It is not, especially for factory sporters shooting hunting bullets.
Jump has no practical effect on throat errosion.
I think you mean 5/1000's or .005. a .100 is one tenth of an inch. That wont happen. We shoot Barnes and we start at .003 off and go out by 2's until we find the sweet spot. Most between .005 and .007 off lands. 10/1000's off lands could be the sweet spot.
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No, I don;t think .100 (that's tenths) off the lands is overly excessive (rather, it's unusual), but I do think that thousandths is too fine of a measurement for incrementally stepping up or down.
As just one example, in my 22-250, the maximum OAL for a Sierra 60gr Varminter bullet is 2.455". The ogive is touching the lands to a dead stop at that measurement. Yet I can get good accuracy down to 2.350" (perhaps even shorter - I haven't tried). But now, were I to dial down at .002" increments, making a COAL of 2.453", I don;t think I would reach an acceptable, accurate OAL except by loading too many cartridges.
Better I would think is to step up or down in .010" or .020" (that's hundredths) increments until you find a sweet spot, then maybe go by thousandths to dial it in....maybe. Maybe not.
As just one example, in my 22-250, the maximum OAL for a Sierra 60gr Varminter bullet is 2.455". The ogive is touching the lands to a dead stop at that measurement. Yet I can get good accuracy down to 2.350" (perhaps even shorter - I haven't tried). But now, were I to dial down at .002" increments, making a COAL of 2.453", I don;t think I would reach an acceptable, accurate OAL except by loading too many cartridges.
Better I would think is to step up or down in .010" or .020" (that's hundredths) increments until you find a sweet spot, then maybe go by thousandths to dial it in....maybe. Maybe not.
The original Barnes "X" bullet, and ostensibly any bullet lacking a lead core, should be seated at least .050" off the lands. So say the good folks at Barnes. http://www.barnesbullets.com/information/load-data/tsx-guidelines/ (Line item 3)
That's "50 thousandths" or "5 hundredths"...however you want to look at it. This is done to keep pressures safe, when using a bullet that is essentially "harder" than the cup n' core or lead designs we have used for decades. If your powder charge weights are near max, you may very well be creating a slight over-pressure situation. I'm not trying to say yer doin' it wrong...I'm just sayin'.
Conventional wisdom has held that one start seeking accuracy by seating .010" off the lands, working back in increments of .005" or .010". The method you describe above, seating .002" deeper with each test load, would be considered laborious and unnecessarily "thorough", by a lot of experienced reloaders. You will surely not miss the sweet spot for accuracy, but neither are you likely to miss it by seating .005" deeper. You state that most of your loads prefer .005" to .007" off the lands. Most of mine prefer .020" to .030" and some guys actually report best accuracy by loading INTO the lands, slightly. (NOTE: Do not do this with max loads!
)Some of the latest observations suggest that it may not be the actual seating depth that is creating better accuracy with these loads; that it is barrel time/harmonics being "tuned" by these minute changes. When you consider how much a slight change in seating depth effects chamber pressure, this is not an unreasonable theory. Also, a lot of good benchrest shooters have become far less obsessed with actual seating depth, and far MORE concerned with absolute concentricity, throughout the action/chamber/case/neck/bullet/bore matrix. If you're interested, I can send you an article about that.
Simple reality is that most factory ammo is loaded AT LEAST .050" off the lands, to ensure they function in a variety of action types, and yet many of these produce MOA accuracy, or close to it. Also, many reloaders follow the recipe in the book, seating their bullets to the recommended OAL, which again, means they cycle in any action and the bullet will be a fairly long, and indeterminate, distance off the lands. Doesn't seem to matter, as accuracy from these handloads is also excellent. These days, advances in machining result in all the components I mentioned above lining up precisely and I think that is largely to "blame" for why attaining MOA accuracy is no longer the Holy Grail it used to be.
Agree with every thing broom_jm says in above post, but need to expand on one little item.
The alignment of the bullet with the bore is the whole crux of accurate shooting. Now, in reloading it is possible to have excessive runout (non-concentric bullet seating) due to reloading dies not being aligned (factory defect, press misalignment or operator error) properly. When chambered, the bullet is pointing off at an angle to the bore.
Then again, you'd be surprised how many barrels are not screwed into the receiver at an absolute zero alignment. That's why many folks pay a competent gunsmith to "blueprint" actions, squaring the face and assuring positive correct bore alignment. The bolt/locking lugs must lock up with centerline perfection, also.
For safety reasons, most manuals recommend the .010" (thousandths) to .030" off-the-lands so that the bullet isn't jammed into the rifling and causing increased chamber pressures upon firing. Depending on the bullet construction, I've set some as close as .005" in single-shot rifles, but you've got to have a micrometer seating die to do so, as the standard run-of-the-mill seating dies can't be relied on to seat to the same dimension exactly every time.
Again, after finding the max COAL by touching the lands with dummy cartridges, the seating depth is backed off the normal .010" to .015", providing they still function through the magazine properly. If not, they get seated deep enough to feed and I don't worry about the offset distance. The accuracy is adjusted by varying the type and weight of the propellent.
The alignment of the bullet with the bore is the whole crux of accurate shooting. Now, in reloading it is possible to have excessive runout (non-concentric bullet seating) due to reloading dies not being aligned (factory defect, press misalignment or operator error) properly. When chambered, the bullet is pointing off at an angle to the bore.
Then again, you'd be surprised how many barrels are not screwed into the receiver at an absolute zero alignment. That's why many folks pay a competent gunsmith to "blueprint" actions, squaring the face and assuring positive correct bore alignment. The bolt/locking lugs must lock up with centerline perfection, also.
For safety reasons, most manuals recommend the .010" (thousandths) to .030" off-the-lands so that the bullet isn't jammed into the rifling and causing increased chamber pressures upon firing. Depending on the bullet construction, I've set some as close as .005" in single-shot rifles, but you've got to have a micrometer seating die to do so, as the standard run-of-the-mill seating dies can't be relied on to seat to the same dimension exactly every time.
Again, after finding the max COAL by touching the lands with dummy cartridges, the seating depth is backed off the normal .010" to .015", providing they still function through the magazine properly. If not, they get seated deep enough to feed and I don't worry about the offset distance. The accuracy is adjusted by varying the type and weight of the propellent.
Off the lands, free bore, running start or off against the lands with a deat stop start.
In most reloading manuels there is a minimum length listed for a particular load/powder/bullet. for those that understand the term relative the measurment or difference between minimum length and off the lands can be measured if they understand transfers and standards. Those with limited abilites shread the neck to make it look like a squid, others take a pair of pliers and crush the neck of a formed case for bullet hold not thinking when the case is chambered the neck will form the neck, push the sides together and as a results loosen the bullet, sounds good but when the bolt closes, the chamber gets dark, and the lights go out.
I drill the flash hole/primer pocket to a diameter that will accommodate a cleaning rod, I size the case, seat a bullet to minimum length then measure the overall length, then remove the bolt, chamber the test case then use a cleaning rod to push the bullet out against the lands, then remove the case and measure the overall length, the difference between the minimum length and maximum overall length is the difference between the two measurements as in off the lands with a minimum OAL case.
Transfer, the dimensions of the chamber for (against the lands) maximum overall length can be transferred to the seater die (if the neck of the test case does not look like a squid) by backing the seater plug/stem out of the die and by backing the lock nut on the die off to prevent contract until adjustments are made. Install the test case in the shell holder, raise the ram, lower the die until the crimp portion of the die contacts the mouth of the case, then back the die out 1/2 turn and secure the die to the press with the lock ring, next adjust the seater plug/stem down to the bullet once contact is made secure the plug.stem to the die with the lock nut. This method turn the seater die into a precision/micro adjustable seater die with the aid of the dial caliper, all one needs to be able to do is measure the height of the stem above the die then zero, if the reloader wants to seat a bullet off the lands .020 thousands, with the seater stem zeroed, loosen the small lock nut, lower the stem .020 thousands then secure the lock nut and start seating.
A friend built 5 rifles, all in 7mm Gibbs, same receivers, barrels etc., one shot patterns, not groups, he asked for help, he did not like the ideal of drilling the primer pocket/flash hole but I thought it was a small sacrifice, I removed the bolt, chambered the test case and then pushed the bullet,,,out of the case, it skidded forward through the long throat then stopped at the lands, the bullet was 170 grains so there was nothing suspect about the length of the bullet, we went to the range with 100 cases loaded with different bullets, powder and every configuration we could think of, there was a small window in the middle that produced one hole group, to either side of that window the groups opened up to patterns. He had the rifle bore scoped, the barrel had been hot at one time but not eroded.
To correct the chamber, set the barrel back .200 thousands and live with the barrel gap down both sides of the barrel channels, open the bolt face, open the magazine and chamber in 7mm Weatherby, or purchase another barrel, problem! he dropped the reamer while attempting to make sizer dies.
.100 off the lands, measurements can be obtained by 'off the lands' off the lands can be obtained by knowing the difference between minimum length and zero off the lands, there is no guarantee the chamber will allow .100 off the lands and not be shorter than minimum length.
I am a fan of the running start, I know moving the lawn and trimming the hedges is a good start when trying for immediate neighborhood acceptance, seating the bullet against the lands are a form of immediate acceptance in the world of reloading, but, in the world of reloading there is most always one factor that is omitted, time and in reloading there are factors that are left out, if for some reason I decide to seat a bullet against the lands, I am going to avoid full loads, this may not be a problem if the bullet is 308 and being shot in a .311 barrel.
F. Guffey
In most reloading manuels there is a minimum length listed for a particular load/powder/bullet. for those that understand the term relative the measurment or difference between minimum length and off the lands can be measured if they understand transfers and standards. Those with limited abilites shread the neck to make it look like a squid, others take a pair of pliers and crush the neck of a formed case for bullet hold not thinking when the case is chambered the neck will form the neck, push the sides together and as a results loosen the bullet, sounds good but when the bolt closes, the chamber gets dark, and the lights go out.
I drill the flash hole/primer pocket to a diameter that will accommodate a cleaning rod, I size the case, seat a bullet to minimum length then measure the overall length, then remove the bolt, chamber the test case then use a cleaning rod to push the bullet out against the lands, then remove the case and measure the overall length, the difference between the minimum length and maximum overall length is the difference between the two measurements as in off the lands with a minimum OAL case.
Transfer, the dimensions of the chamber for (against the lands) maximum overall length can be transferred to the seater die (if the neck of the test case does not look like a squid) by backing the seater plug/stem out of the die and by backing the lock nut on the die off to prevent contract until adjustments are made. Install the test case in the shell holder, raise the ram, lower the die until the crimp portion of the die contacts the mouth of the case, then back the die out 1/2 turn and secure the die to the press with the lock ring, next adjust the seater plug/stem down to the bullet once contact is made secure the plug.stem to the die with the lock nut. This method turn the seater die into a precision/micro adjustable seater die with the aid of the dial caliper, all one needs to be able to do is measure the height of the stem above the die then zero, if the reloader wants to seat a bullet off the lands .020 thousands, with the seater stem zeroed, loosen the small lock nut, lower the stem .020 thousands then secure the lock nut and start seating.
A friend built 5 rifles, all in 7mm Gibbs, same receivers, barrels etc., one shot patterns, not groups, he asked for help, he did not like the ideal of drilling the primer pocket/flash hole but I thought it was a small sacrifice, I removed the bolt, chambered the test case and then pushed the bullet,,,out of the case, it skidded forward through the long throat then stopped at the lands, the bullet was 170 grains so there was nothing suspect about the length of the bullet, we went to the range with 100 cases loaded with different bullets, powder and every configuration we could think of, there was a small window in the middle that produced one hole group, to either side of that window the groups opened up to patterns. He had the rifle bore scoped, the barrel had been hot at one time but not eroded.
To correct the chamber, set the barrel back .200 thousands and live with the barrel gap down both sides of the barrel channels, open the bolt face, open the magazine and chamber in 7mm Weatherby, or purchase another barrel, problem! he dropped the reamer while attempting to make sizer dies.
.100 off the lands, measurements can be obtained by 'off the lands' off the lands can be obtained by knowing the difference between minimum length and zero off the lands, there is no guarantee the chamber will allow .100 off the lands and not be shorter than minimum length.
I am a fan of the running start, I know moving the lawn and trimming the hedges is a good start when trying for immediate neighborhood acceptance, seating the bullet against the lands are a form of immediate acceptance in the world of reloading, but, in the world of reloading there is most always one factor that is omitted, time and in reloading there are factors that are left out, if for some reason I decide to seat a bullet against the lands, I am going to avoid full loads, this may not be a problem if the bullet is 308 and being shot in a .311 barrel.
F. Guffey
broom_jm, a case that has the neck cut with a saw through the neck to decrease bullet hold, to me, looks like a squid, to avoid starting over every day I prefer the bullet hold/neck tension of a neck that is sized, again, the test case can be used as a transfer and can be used to turn a seater die into a seater that that is adjustable in thousands for seating when the stem protrusion is measured with a dial caliper
No guestimates because the thread of the stem is in a foreign language like the die, 14 threads per inch, If I choose to back the die out .010 thousands, I measure the height of the die above the press, then zero the dial caliper and adjust the die to .010 thousands, the reverse works, to lower the die .010 thousands, make contact with the shell holder, zero, then lower the die .010 thousands or any number of settings without guessing degrees in thousands.
F. Guffey
No guestimates because the thread of the stem is in a foreign language like the die, 14 threads per inch, If I choose to back the die out .010 thousands, I measure the height of the die above the press, then zero the dial caliper and adjust the die to .010 thousands, the reverse works, to lower the die .010 thousands, make contact with the shell holder, zero, then lower the die .010 thousands or any number of settings without guessing degrees in thousands.
F. Guffey
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Took me a couple of Jim Beam's to get through it. I use h/c lead in my Marlins and seat bullets so that they just touch the lands. I may be wrong, but that's the way I do it.
Dan
i'm just glad that ya don't have to go through all that crap to get good accuracy!!
i wouldn't even bat an eye at .100" off the lands, as i've stated before i have a 280 remington that due to the brno magazine length i have to seat bullets around .180" off the lands and this gun is remarkably accurate with most of the stuff i've run thru it and for that matter every load tried has been acceptable for hunting.
entirely too much is made of bullet seating depth!!
i wouldn't even bat an eye at .100" off the lands, as i've stated before i have a 280 remington that due to the brno magazine length i have to seat bullets around .180" off the lands and this gun is remarkably accurate with most of the stuff i've run thru it and for that matter every load tried has been acceptable for hunting.
entirely too much is made of bullet seating depth!!
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