Crimping Rifle Bullets

hunterjoe21 · Posted: Fri Dec 21, 2018 11:27 pm Post subject: Re: Crimping Rifle Bullets

English Mike wrote:

slimjim wrote:

hunterjoe, you are getting some good recoil therapy. I don't look for any differences in accuracy. I just make crimping part of the process and develop loads from there.

If nowt else, it removes one variable from the process & that can only be a good thing.

I was kinda hoping to cut a corner by just adding a crimp to an existing load, knowing that there ain't no such thing as a free lunch. I never did "tweak" my seating depth with either the .270 or the .300, so I might play with that and include crimping. Sounds like I'm playing with more than one variable at a time though.

slimjim · Posted: Sat Dec 22, 2018 7:38 am Post subject: Re: Crimping Rifle Bullets

changing seating depth is a powerful "lever" for tuning group size. I started with 0.025" increments but now use 0.015" increments. I've read were others use 0.010" or 0.005" increments. If you always crimp, its not a variable. In fact, it reduces standard deviation in neck tension so it lessens one of the variables. The picture below is results from my 6.8mm SPC.

hunterjoe21 · Posted: Sat Dec 22, 2018 11:25 am Post subject: Re: Crimping Rifle Bullets

Slim,

I found the same thing when I worked up the load for my .243. I was getting good groups, but when I started adjusting my seating depth, it really showed the true accuracy of that load. Nowhere near 0.1" though...

Just out of curiosity, is 2.270" the "shortest" you tried in your 6.8? I've found that sometimes shorter works too.

slimjim · Posted: Sat Dec 22, 2018 1:11 pm Post subject: Re: Crimping Rifle Bullets

What surprised me was those groups were shot with a simple 3-9x Accupoint with a green triangle reticle vs fine crosshairs and 16x magnification.

Vince · Posted: Sat Dec 22, 2018 3:10 pm Post subject: Re: Crimping Rifle Bullets

I gotta revisit my loads with a view to “adjusting” the COAL. It seems that there is good accuracy to be gained.

hunterjoe21 · Posted: Sun Dec 23, 2018 12:52 pm Post subject: Re: Crimping Rifle Bullets

Vince wrote:

I gotta revisit my loads with a view to “adjusting” the COAL. It seems that there is good accuracy to be gained.

Vince,

Here's a link to an old post on Berger's website regarding adjusting COAL in order to achieve better accuracy:

www.bergerbullets.com/...our-rifle/

It addresses issues people were having in getting the VLD bullets to shoot accurately, but I believe the concept can be applied to any bullet/rifle combination.

I've used a slight variation of their tests in order to tune my loads in the past, and am planning additional tests for both my .270 and .300 Win Mag loads, including the crimp now that I have the LEE dies.

OldSchoolRanger · Member Joined: Feb 15, 2017 Posts: 88

Bushmaster wrote:

The only rifle cartridge that I crimp (using a FCD) is .30-30.

I agree with Bushy, with my other calibers, I just use the built in roll/taper crimp function in the seating die.

PaulS · Posted: Fri May 03, 2019 9:18 pm Post subject: Re: Crimping Rifle Bullets

I don't crimp my rifle loads. I figure it just adds one more thing to the list of variables. Hey Bushy... I don't crimp my 30-30 loads either, but then I shoot them through a single shot rifle and not a lever action. Wink

Bushmaster · Posted: Fri May 03, 2019 10:23 pm Post subject: Re: Crimping Rifle Bullets

That would make a difference. That means you can also shoot pointed bullets too.

slimjim · Posted: Sat May 04, 2019 4:48 am Post subject: Re: Crimping Rifle Bullets

OldSchoolRanger wrote:

I just use the built in roll/taper crimp function in the seating die.

My experience with built-in roll/taper crimp function has not been positive. That function is designed to work only with the cannelure and if your case trim is not exact, you get varying tension from the crimp. It can also lead to deformation in the case neck that you can't see but is significant enough to impede a round from chambering in a semi-auto. When this happened to me, Elvis helped be figure this out.

The Lee Collet Crimp die does not have either of these issues. Plus a collet crimp (not the built in feature) actually reduces one of the reloading variables - neck tension. I have measured it with a forces scale and the standard deviation of neck tension was reduced by 50%.