Home Forums Hunting & Shooting AR and Tactical Rifles Handloading for an AR

I’ve been reloading for close to 40 yrs. and loading for numerous 223’s over the years. But none were semi-autos or AR’s. Weelll, I just got an AR. I understand that the basics are the same, but my question concerns crimping. I’ve talked to a couple of folks who reload for AR’s......one says he never crimps but maintains a tight bullet to neck fit. The other uses bullets that allow him to roll crimp into the cannelure. I thought maybe some of you guys might have some insite as to how I should approach crimping. Roll crimp, taper crimp, or no crimp? I also bought a few PMags which all seem to measure 2.25 inside max so how short is my max OAL to feed well in plastic magazines? Thanks in advance for your help.

No crimp.
2.25, or 2.255 oal. If you use metal ASC mags you can go to 2.3"

I set my seater to put a slight crimp on the bullet. That also helps with reducing TIR. Something a lot of guys don't understand. A Pmag is generally 2.260" on the inside. So most of us run our OAL to somewhere around 2.250-2.255" to allow for reliable feeding and loading of the mags.

Same here.
This is pretty much the standard.

just for s&g's i bought one of the Lee factory crimp dies to try out. done correctly it took 3/4 inch off my groups. ymmv

I suspect you had either a runout or neck tension problem prior to crimping.

most likely tension. i have that problem alot

I use the crimp option on an RCBS AR15 seater die. It is a taper crimp that has the roll crimp at the end of a longer taper just incase your case length is not consistant. (Supposedly) It seems to work better with fewer crushed shoulders than a standard die with a roll crimp. But, to be consistent, you need to get your cases as close to the same lenght as you can. I have also used a Lee crimp die and that works well as long as you are not power crimping them. They are nice when your cases are not consistently the same lenght.

kwg

My mileage varied. My results were directly opposite.

No crimp. Also bump the shoulders a bit more than you would with a bolt rifle, 0.003 is good.

No crimp.

Folks that shoot a tighter group with a crimp VS. no crimp, most likely have neck tension variance. By crimping, it helps to equalize the round to round release tension. Annealing regularly can help equalize release tension. Keeping cases sorted by brand and number of times reloaded can also help.

"I set my seater to put a slight crimp on the bullet. That also helps with reducing TIR. Something a lot of guys don't understand. A Pmag is generally 2.260" on the inside. So most of us run our OAL to somewhere around 2.250-2.255" to allow for reliable feeding and loading of the mags." [/quote]



What is TIR? Also, is it required that you use "small base" dies for AR reloads?

Thanks

Total Indicator Runout.
No.

Anything to the right of the 100ths place in overall length is irrelevant.

Small base dies are rarely needed and usually counterproductive. AR chambers are usually rather loose.

Yes sir. Total indicatior reading, but for run-out. I like straight ammo. It tends to shoot better than crooked chidt. Im running small base dies for my CLE chambers. Get good accuracy and good enough longevity out of my brass. Not that im too concerned about it. Brass is free around here.

I think a Lee factory crimp die is a good tool to use on ammo that's going to be fired in an auto loading rifle.

One of the first things I did to insure reliability of the ammo I handload was to buy a Dillon case gauge. My brass has been shot thru many different chambers but after it is resized now and it gauges I know it will chamber and lock up . If a case fails to gauge the first time I will try to resize it again if it then gauges fine , if it don't it goes in the recycle bucket I won't even save it for the bolt guns. Consistancy when loading for AR's counts alot to insure reliability. MB

I have never crimped ammo for my AR's and never had a problem, also have never needed small-base dies.

I have to express some curiosity as to how roll crimping can reduce total indicated runout??

Thanks guys for the feedback. I think I’ll go with “no crimp”. If I have a problem, I’ll try the factory crimp die then. Looks like an OAL of 2.25” or less should be good to go. Will probably go 2.24” and see how that works. Not trying for benchrest accuracy, just something that works well if they start coming over the wall, so to speak! Thanks again.

I'm with Bristoe on this one.