Home Forums Reloading Handgun Reloading Does crimp affect accuracy?

I haven’t loaded much handgun ammo so kinda new at this. I loaded some 44 magnum and shot it through two different rifles with varying accuracy. They were all loaded with the same bullet, powder and primer. The brass was previously fired and I noticed when seating and crimping the bullets some would seem to start the crimping sooner than others. I’m assuming this would cause a tighter crimp. Does that affect accuracy? Can someone enlighten me please?

Thanks in advance

Sure crimp could affect accuracy. If you are getting differing crimps, you might want to trim all your brass to a uniform length.

I only use cast bullets in all handgun ammo but I'm pretty sure the same advice will apply to jacketed bullets. You'll have to experiment, but I've found generally that the lightest crimp (regardless of the crimp type) that will prevent bullet movement will provide best accuracy. Also, and there are exceptions to everything, I've yet to see any indication that a (needlessly) heavy crimp promotes better powder ignition. I think many shooters crimp far more than necessary and this will often cause a deterioration in accuracy because there is a distortion of the bullet. Some like to use a Lee Factory Crimp die, but if you're doing everything right, such a die is not needed.

Directions for H110 says to use a heavy crimp with 44 mag.

Consistency of the crimp is more important than how much ( assuming it is enough). As Gregintenn mentions,you might want to trim your brass so all are the same length.

I agree with saddlesore, consistent crimps are important. I seat and crimp in separate steps as I think it helps witb consistency and prevents any potential shaving of cast bullets. I seldom have mixed brass in the same box...each box is same lot and brand, same number of firings.

Thanks everyone

Per Dillon:

8.5. If there is no groove or cannelure, do not over crimp the bullet. Over crimping can damage the bullet
and reduce the “hold” on the bullet due to the bullet being deformed and the brass case springing back
away from the deformed bullet. Crimping a bullet without a crimp groove should only reduce the
diameter of the brass case mouth/outer diameter .001-.002”. A reduction of case mouth diameter
greater than .002” may cause bullet deformation and a loose bullet. Note-- it is not necessary to use
the cannelure if your COAL is not compatible with the location of the cannelure.

https://www.dilloncdn.com/manuals/dillon-die-instructions-english.pdf

I was putting a crimp on my rounds that reduced case size .005 when I check. What I learned that a .002 crimp is barely noticeable at the press handle.

If your bullet does not have a cannelure, all you need to do is get rid of the bell.

No, it doesn't effect accuracy. But the crimp's purpose is hold the bullet against setback and pulling.

The uneven crimping is due to varying case lengths being used with a standard roll crimp.

The best way to crimp 44mag is to do the crimping in a separate step. I happen to believe that the Lee Collet Crimp die is the best tool for the job. It will crimp regardless of cannelure.

Back your seating/crimp die off so that it doesn't crimp and use it only for seating.

https://sites.google.com/site/hobbyhintstricksideas/home/crimping-44-magnum

The bullets were hornady 240 grain xtp so they have a cannilure. Thanks for the responses

The brass needs to be trimmed to the same length for the most consistent crimp. A lot of work for some applications. I like the Lee FCD for auto loading pistols that I don't want to bother trimming. Sometimes seating and crimping separately gives the best results. I do it that way more than not.

If I have a bunch of brass I want to to load for casual use, but I don't want to trim it, I'll segregate by length and readjust the crimp die for each length.

I’ve never trimmed a piece of handgun brass in my life. As long as you crimp in a separate step no problems will be had. When you seat and crimp in the same step is when cases will buckle.

Look into taper crimping dies

What rifles?

You may have bore size and / or twist rate issues to deal with.

My Marlin 444 shoots the .429 dia 240 gr XTP "ok", but likes the .430 dia 240 gr Zero bullet much better. In my 444 it's a bore size situation. Slug your bore and measure it.

Your crimp issue is easy. Buy a Lee Factory Crimp Die, the non carbide ring type. Crimp in a final step and don't give it another thought.

Taper crimp.

Even with a taper crimp if case mouths are uneven and cases vary in length don't expect the nth degree of precision on target paper. Unevenness of bullet pull as the bullet starts its journey can't help but effect things detrimentally. That said, for the kind of shooting I do these days anymore, glorified plinking mostly, I'm no longer as anal about trimming and continue to roll crimp revolver ammo just like I always have done. The steel swingers dance and the beer cans roll, and life is good. Auto pistol ammo gets taper crimped of course.

No to both of you.

for me this is my general rule for crimps
revolver = roll crimp the more consistent the length the more consistent the crimp the more consistent the load which should equal better accuracy.

Auto pistols.= taper crimp I think link is a little more tolerant of variances for consistent crimp here but considering in an auto pistol your head spacing off of the end of the case it becomes as relevant.

rifles with tubular magazines I like a good firm roll crimp and once again the more consistent the length the more consistent the crimp.

bolt guns and they are chambered 308 family and smaller I generally do not cramp provided they have good adequate neck tension..

starting about 30-06 or for sure 300 Magnum class I give them a nice tight roll crimp.

now I do like the Lee factory crimp dies in tubular magazine rifles and auto loading pistols quite well.

Depends. Ive not really seen much of a difference in group size, but it may matter if you are reaching out there pretty far and have a serious rig to shoot super tiny groups at extended ranges. For the person who is shooting game and paper with a basic hunting rifle, youre most likely not going to notice any difference in accuracy. I crimp more for the reliability of the ammo when hunting and to your issue, all brass needs to be trimmed to the same length for proper crimping. Crimp in a separate step, ALWAYS