I'm reloading for my rifles, at this point, my main focus is my 7mm Mag BAR. I've got the Hornady LnL OAL gauge and Hornady Bullet Comparator. The bullet I'm using is a 150gn Nosler E-Tip. I measured the space to the rifling lands, and have my seating die set to as close to 2.7715" (measured using the Comparator, so the true OAL is longer) as I can get it. This places the bullet .075" off the rifling (using the comparator, the bullet is on the rifling @ 2.8465"). Nosler says the E-Tip should be .050-.100 off the lands for "Optimum Accuracy". Two main questions; one, using the comparator with the 7-28 collet takes the measurement at a much different point then where the RCBS seating die contacts the bullet. The 4-25 collet is MUCH closer to the same place the seating die contacts it. Is this likely to be an issue with reliable seating? Should I instead be using the 4-25 collet for measuring the 7mm? The other question is the seating depth seems to fluctuate as much as .0085. Am I worrying too much about such a relatively small variation? Is it enough to throw off accuracy? FWIW, loaded like above, I've gotten roughly 1/4" grouping @ 100yd with my BAR MkII, and that 1/4" could be from the shooter (me), not the rifle or bullet.
Cartridge OAL question
- Thread starter 357SigFan
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Jim Watson
Member
1/4" with a BAR?
Don't change ANYTHING.
Don't change ANYTHING.
ranger335v
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Don't even talk loudly around it!
Ok, I'm getting frustrated here. I've got a box loaded just like the batch that shot about 1/4" @ 100yd, and I'm not changing *anything* until next spring as they way it is now, it's dead on for deer season and I'm not messing with it.
But for the future, I'm trying to get my seating die set up for the best seating consistency. The problem I found causing my varying seating depths was with pressure, since the die has a crimp on it. Too little pressure and it'll seat the bullet near the target depth, but put no or not enough crimp. Too much and it shortens the cartridge and bulges the neck. Or anywhere in between those extremes. So my "solution" was to raise up the die in the press so when I bring the handle to the bottom of its travel, the round will get just a touch of crimp and the bullet depth should be as close to perfect as it can get. The theory was good until I discovered inconsistent brass length.
According to my Hornady manual, the 7mm Rem Mag case should be 2.5". The Winchester brass that's been through the gun at least once then neck sized is all right around that give or take a VERY small amount. The brand new Remington brass I picked up at Cabelas (makes more sense to get the new brass for like $65 per 100 vs about $35 per 20 just to shoot for the brass) measures 2.4935”. I’m planning on getting a case trimmer, but should I set the die up to not apply any crimp, since the E-Tip is solid with zero give, unlike a lead core/copper jacket bullet that will typically give a little for the crimp, or should I look into a Lee factory crimp as a second step after seating the bullet with the RCBS die?
But for the future, I'm trying to get my seating die set up for the best seating consistency. The problem I found causing my varying seating depths was with pressure, since the die has a crimp on it. Too little pressure and it'll seat the bullet near the target depth, but put no or not enough crimp. Too much and it shortens the cartridge and bulges the neck. Or anywhere in between those extremes. So my "solution" was to raise up the die in the press so when I bring the handle to the bottom of its travel, the round will get just a touch of crimp and the bullet depth should be as close to perfect as it can get. The theory was good until I discovered inconsistent brass length.
According to my Hornady manual, the 7mm Rem Mag case should be 2.5". The Winchester brass that's been through the gun at least once then neck sized is all right around that give or take a VERY small amount. The brand new Remington brass I picked up at Cabelas (makes more sense to get the new brass for like $65 per 100 vs about $35 per 20 just to shoot for the brass) measures 2.4935”. I’m planning on getting a case trimmer, but should I set the die up to not apply any crimp, since the E-Tip is solid with zero give, unlike a lead core/copper jacket bullet that will typically give a little for the crimp, or should I look into a Lee factory crimp as a second step after seating the bullet with the RCBS die?
USSR
Member
No need for a crimp with your rifle/load. As long as you have sufficient neck tension, your bullet will not move.
Don
ArchAngelCD
Member.
Amen to that brother!!!
I know a few guys that would kill for that kind of accuracy with their "expensive" hunting rifles.
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