Taper Crimp .223 Dies


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Special_K
October 4, 2008, 09:16 AM
I am just getting into reloading and made my first 25 rounds last night! :) However I did a little reading afterwords to find out that a taper crimp die should be used in semi-automatic rifles like the DPMS AR-15 I plan to use them in.

So am I going to be ok with a non-taper crimp die for reloads in an AR-15?

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RecoilRob
October 4, 2008, 10:16 AM
Many people don't crimp their AR ammo, so you should be fine.

But, to check if your particular setup has sufficient neck tension to hold the bullet securely during feeding, you can do a test.

Measure the OAL and chamber the round (feeding from mag) from bolt lock. Eject and measure again. Did the OAL change? No is good! Yes (shorter) is bad. Yes means you need to crimp.

If the OAL didn't change, load two in the mag (previously measured, of course) load and fire the first. Eject the second and measure it. Having been loaded at full bolt velocity, it should be the acid test of the neck tension. No movement....shoot away! Good luck and have fun.

ClarkEMyers
October 4, 2008, 10:47 AM
No should but rather it depends.

Among other things it depends on what the load is for and that will influence the choice of bullet. As a practical matter only bullets with crimping grooves can be roll crimped (over the front driving band on handguns and other exceptions exist) and such might well be chosen for end of the world as we know it loads. Bullets that don't have crimping grooves can't be roll crimped but might be taper crimped. Notice that taper crimp covers a multitude of possibilities including Lee's Final Crimp and Redding's Profile Crimp. Accuracy loads for a bolt action are often not crimped - including cases that are loaded with bushing dies for more control of the neck tension - and loads for gas guns may not be crimped for some purposes but arguably should be for most purposes including possible rough handling outside the firearm. Cartridges that are going to be carried on stripper clips and handled roughly before hurried refills of 20 and 30 round magazines may need more crimp than over length loads that don't even fit a magazine and will be single loaded with a single loading magazine filler.

My own practice is to avoid crimping anything that will be shot at small varmints - ground squirrels or prairie dogs - at longer ranges where the ammunition will be handled gently - and loaded with bushing dies for good control of neck tension - and to crimp everything else as appropriate to the bullet chosen.

Walkalong
October 4, 2008, 12:51 PM
I taper crimp some .223. I use a Redding die. It is great for non cannelured bullets, but will work with bullets with a cannelure as well. Some cannelured bullets these days have a pitiful excuse for a cannelure. It's more like just a mark around the bullet. The Taper crimp die works real well for those as well.

With bullets with a GOOD cannelure that will be used for plinking / defensive practice / blasting, I use a roll crimp.

rcmodel
October 4, 2008, 01:45 PM
I did a somewhat limited test using a Colt AR & a CZ-527 last year.

Using a Lee Collet crimp die on 55 grain Nosler Ballistic-Tip bullets. (Bullets that do not have a crimping cannulure.)

The end result was both rifles shot slightly smaller groups with the crimped loads.

All I can surmise from that is, crimping non-canulured bullets didn't hurt accuracy, and with the two rifles I tested, did improve accuracy very slightly enough to measure on paper.

I have not tested the roll-crimp provided by my standard RCBS .223 dies, so I can't say what effect that might have.

rcmodel

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