does crimping brass make for better accuracy

G’day loaded some 7mm rem mag loads the other day and they shot 11/4’’ couldn’t figure out why they were doing this as they shot 1/2’’ - 5/8’’ a week before when I got to thinking I had forgot to crimp them so I crimped the rest and got the 1/2’’ again is this normal and has anybody had a similar case ? some say crimping can be dangerous others say it has no affect on accuracy and others simply say there’s no need for it so just wondering cause I haven’t had the 7mm for any great length of time

G’day grandadbushy,
Crimping can improve accuracy by uniforming the release of the projectile from the case. It may not work on all projectiles but is one of the things that should be tried whenever you are working up a load. Tube magazine rifles should always have crimped bullets to stop them pounding back into the case during recoil, and over-crimping on projectiles without a cannelure ring should be avoided as this can cause jacket separation. World champion shooters will often crimp, depending on load, so if it is good for them it is worth trying for us, and you own results show your load benefits from it, Cheers.

Thanks no1mk3 that makes it a little clearer on the uniforming of release of the projectile this may be the factor in my case hence the little bit better accuracy with the crimped ones thanks mate

I think this is a question for @sungazer and @gwion, who’d be pretty much experts in loading for precision.

Neck Tension certainly effects accuracy. Getting neck tension right or consistent is one of the hardest things to get right in reloading. One of the components is how much elasticity your brass has. As I think everybody knows your brass starts from a nice soft stage when new and work hardens as you resize and shoot it. I am trying to get a consistent brass hardness/softness by annealing on every reload.I am then using a bushing die which just pushes in on the outside of the neck just a few thou. Creating a very small neck tension.

Using a crimp die is a way of creating neck tension once the bullet is loaded. It can put a good deal of pressure on the case. So a lot of neck tension. This can work better in some cases as it takes you away from the small variations in small gross numbers to small variations in larger gross numbers. Hope this makes sense By crimping you could be creating a smaller overall % difference in neck tension.

As no1mk3 said don’t go to heavy on the crimp die as some if not all will really turn the top edge of the neck cutting into the jacket.


Thanks fellas yes I understand what you are saying and that tension is rather important I had found that the unannealed brass was not consistent with their neck tension but I got better groups by crimping them so maybe anneal then a light crimp which is what I have just done haven’t fired any yet maybe tomorrow

Never crimped but as i understand it Sungazer has covered most of it… all about consistent neck tension which can also be achieved by reeming and turning your neck brass.
I think there is also a point to crimping that it allows pressure to build in the case before pushing the bullet into the throat, similar to jamming bullets…

My experience is the same when reloading without annealing.

Since asking about this I have shot the bullets I made up with annealing and a crimp and with the 7mm mag it was tighter and more consistent and with the 22-250 it was only minimal either way so i’m happier with the process and will continue to anneal and crimp thanks for all the help fellas


I would say yes for cast bullets. Cant speak for jacketed. I believe it uniforms the shot pressure of the load, well it most certainly does with cast subsonic loads in .308

Now add some neck turning for sh*ts and giggles.

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