Gets you wondering! Did they really or not go into full disclosure
Crimping and neck tension
- Thread starter Dmagna
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Mikecr
Well-Known Member
They set up a some kind of serious problem condition, and noted that crimping alleviated much of that.
Another issue: crimping is into a cannelure.
How do you get that groove to the right position on the bullet to result in tested best CBTO?
If you didn't, you would end up seating to where you had to for a crimp -instead of the best place.
Even if you were able to gain a better powder node, or at least not hurt it with crimping, that is not going to cover for a poor CBTO.
For bolt action rifle potentials, crimping just doesn't seem like something you would do to gain accuracy.
And certainly crimping is not needed for bolt actions.
Another issue: crimping is into a cannelure.
How do you get that groove to the right position on the bullet to result in tested best CBTO?
If you didn't, you would end up seating to where you had to for a crimp -instead of the best place.
Even if you were able to gain a better powder node, or at least not hurt it with crimping, that is not going to cover for a poor CBTO.
For bolt action rifle potentials, crimping just doesn't seem like something you would do to gain accuracy.
And certainly crimping is not needed for bolt actions.
I'm going to experiment with crimping for one of my 22-250's. It prefers Sierra 55 grain GameKings, there is only about 0.160" of the bullet in the case neck and it doesn't take much effort to disturb it. The rifle shoots very well and it'll be interesting to test.
Mikecr
Well-Known Member
So @justinp61 will you have a bullet groove to crimp into with your current seating?
No, not ideal I know.
Mikecr
Well-Known Member
I don't see how that's doing anything without a groove/cannelure.
A cannelure is only really needed for a roll type crimp. A taper crimp squezzes the brass. Every semi auto pistol round has a taper crimp from the factory. No cannelure.
If the crimp puts even a small groove in the bullet it'll help keep it from being moved in the case. I'd pull one but I don't have a .224 collet.
Hugnot
Well-Known Member
I crimp ammo:
Bullets intended for 5.56/.223 AR ammo; the cannelure is positioned so a crimp into the cannelure will make a COAL round that will fit into an AR magazine. Like .224 62 grain Hornady FMJ, SPBT, HPBT.
I don't anneal after every firing but crimp after every bullet seating. Crimping counter acts brass spring back caused by work hardening that might cause neck tension variations.
I think the shallow annular grooves in bullets resulting by Lee FCD use are no big deal provided jacket/core deformation upsetting bullet balance does not occur. Appearance differences in crimped & uncrimped rounds are easily seen. ^^justinp61. The amount of force needed to seat & pull bullets from uncrimped rounds that have been subjected to neck work-hardening varies thus neck tension would also vary.
Picky benchrest shooters don't crimp bullets but maintain uniform neck tensions round to round.
In the:
https://apps.dtic.mil/docs/citations/ADA341390
Bullets were pulled. Rounds that had unpulled bullets were not tested. My thinking is that firing a round then resizing the neck would introduce more work hardening than only bullet pulling. The test shows crimped bullet ammo had better performance.
Bullets intended for 5.56/.223 AR ammo; the cannelure is positioned so a crimp into the cannelure will make a COAL round that will fit into an AR magazine. Like .224 62 grain Hornady FMJ, SPBT, HPBT.
I don't anneal after every firing but crimp after every bullet seating. Crimping counter acts brass spring back caused by work hardening that might cause neck tension variations.
I think the shallow annular grooves in bullets resulting by Lee FCD use are no big deal provided jacket/core deformation upsetting bullet balance does not occur. Appearance differences in crimped & uncrimped rounds are easily seen. ^^justinp61. The amount of force needed to seat & pull bullets from uncrimped rounds that have been subjected to neck work-hardening varies thus neck tension would also vary.
Picky benchrest shooters don't crimp bullets but maintain uniform neck tensions round to round.
In the:
https://apps.dtic.mil/docs/citations/ADA341390
Bullets were pulled. Rounds that had unpulled bullets were not tested. My thinking is that firing a round then resizing the neck would introduce more work hardening than only bullet pulling. The test shows crimped bullet ammo had better performance.
Crimping has normally improved precision, the times I've done it. Same with buddies that tried crimping their favorite reloads.
Not sure it would help much if a guy turns blue in the face during extensive load development to find the Goldilocks zone / load for his rifle.
But for the majority of reloaders who don't invest that kinda time into load development, I think the odds are very good that precision will improve with crimping. And I suspect that's one reason factory ammo has customarily / historically been crimped.
When I crimped my AR-15 loads with the LFC die, the improvement in precision was large, and undeniable. And I was crimping on bullets with no bullet cannelure.
Not sure it would help much if a guy turns blue in the face during extensive load development to find the Goldilocks zone / load for his rifle.
But for the majority of reloaders who don't invest that kinda time into load development, I think the odds are very good that precision will improve with crimping. And I suspect that's one reason factory ammo has customarily / historically been crimped.
When I crimped my AR-15 loads with the LFC die, the improvement in precision was large, and undeniable. And I was crimping on bullets with no bullet cannelure.
