Crimping affects on accuracy

V

Vect0rstar

Member
I was wondering what your opinion is on crimping and how it affects accuracy. I've read that it can be both beneficial and detrimental concerning accuracy. I'm loading 53 gr. Vmaxs for my ar with no crimp and am getting pretty good results.

From what I've read long range precision shooters do not crimp because they have consistent neck tension. Is there any way I can get consistent neck tension without buying extra equipment and only using my fl sizing die? Do you think it is even worth crimping in the first place? If a bullet has a cannelure does that make a difference in if you crimp or not?
 
only way to know if it performs better in your gun is to test it.

i give all my ammo about a 1/4 turn crimp with a lee FCD - just enough to give it a kiss.



some guns benefit from it, others dont.
 
The expander button makes for consistent neck tension as the neck is always the same size ID. Tge problem is you get what you get if you don't have different size expanders. We use bushing dies and brass with consistent thickness to adjust neck tension. Anything over about 0.006 tension is usually detrimental to accuracy. Many standard dies cause much greater than that.

A bullet with a cannrleur does not automatically get a crimp. We shoot oddball bullets in our wildcats that often either completely hide or expose the groove.

Personally I don't crimp anything except in rare occasions like on my full suto loads or pretty hard kickers with big bullets.

Greg
 
I crimp my hunting ammo because some of it usually ends up getting carried through the rain or dropped in snow. I use a lee factory crimper and I now only crimp with the die in a Hornady lock n load turret press because it has a very consistent end to the top of the stroke. When I was crimping with a single stage the crimp consistency was more determined by the pressure I put on it.

As for accuracy, ether it hurts accuracy or it doesn't, I've never seen a crimp improve accuracy and I did a little testing with it when I was shooting an AR in local competitions. But my hunting AR is still holding well under .75 MOA even with a 4x scope, shooting 65 SGK crimped.

If you don't WANT to crimp your ammo in most cases you don't need to.
 
I crimp 444 Marlin, 30/30, 44 mag, some 357 Mag

22 Horney lee factory crimp(replace the locking ring with a Hornady so you can repeat the amount
of crimp you are giving your loads)

That is all

IN order to get a consistent crimp, the cases have to be trimmed to exactly the same length, or you get varying amounts of crimp = pressure spikes on some cases. Also, cases with thicker/thinner necks will get more/less crimp.

What a can of worms.
 
for rifles I only crimp for use in a tubular magazine.

handguns get crimped. for semi autos they get a taper crimp, if you don't crimp the bell back in they won't feed properly. revolvers get a roll crimp to hold bullets in place during recoil
 
I have a three part study involving crimping of cartridges in two 223's, bolt and AR, and a 243 Win that show what the same load same everything except crimp will do if you but zero to up to 50 ft lbs of crimp on the neck using a LEE crimper by as much as 40% It does make a difference.. PM me if anyone wants some links.

Greg
 
Pretty sure the crimp question has been answered.
Consistent neck tension requires, at the very least, sorting your brass.
The least expensive way to increase neck tension is to polish your expander ball.
Start by trying to take off .0005". Chuck it in a drill and try to remove as little as possible. You might want to buy another expander ball as a backup, just in case, 'cause you can't put material back on...:)
 
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I only crimp AR ammo to avoid bullet set back from repeated loading and unloading. It doesn't make enough difference in my AR requirements to change a thing.
 
Originally Posted By: AnkenyI only crimp AR ammo to avoid bullet set back from repeated loading and unloading. It doesn't make enough difference in my AR requirements to change a thing.

^^^^^Yep, an action full of H335 is not a good thing.
frown.gif


Regards,
hm
 
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