Crimp for AR loads???

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Kpuck08

Member
How many people crimp their loads when running a gas gun? In my .223 53Vmax loads crimping lowered my ES by about 150 fps. I getting ready to start loading for my 6ARC and curious if I should order a crimp die for it.

With the factory ammo, I can drop the bolt and load a round, then when I extract the round there are quite a few marks on the bullet. There are some marks that appear to be from the rifling as im pretty sure my barrel has a short throat, but the others are lower on the bullet and parallel with the neck of the case.

I know a crimp wont stop the markings on the bullet. Hopefully my reloads will be able to chamber and be removed with no markings on the bullets. An AR action is pretty violent though. Not sure if the Bullet can get pushed in more or when it finally slams home if the bullet slides out a bit??

Crimping can be a pain. trim lengths have to all be the same, not just within range. and just another step added to the whole process. Just trying to talk myself into it i guess.
 
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I always liked crimping my hunting ammo just because I'm always hunting in the snow and getting it everywhere and even with the action and dust protector shut the gun and every other metal thing I was hunting with would turn into a frost ball when bringing it inside from a night hunting well below zero. And along with the hunting ammo getting fired less and more likely to sit on the shelf for awhile I figured the crimp couldnt hurt sealing the elements out.

All bullets get dinged up on the feed ramps but I've almost never had a seating problem when feeding and I have never hesitated from feeding the same first round from the mag and keep an eye on it. I did just recently have problems with some varmint bullets with big hollow points but it was old ammo that wasnt crimped, they were very soft bullets prone to deforming so I annealed the necks and left them loose then then left them rattle around moving and storage for a couple years, I have fired a couple hundred of the same HP bullets while crimped without an issue.

Crimping wont help accuracy at all, I remember testing my same lee crimp 223 die with my 24" bull upper with meticulously trimmed and loaded lapua brass and 69 SMK, crimping didnt hurt a lot but it was a difference in fliers.

Just a couple days ago I was walking through cabelas and I picked up a jar of primer and bullet sealer. I thought it sounded great at first but I'm in the middle of switching to all HBN lubed bullets and after thinking about trying to seal small primers, wondering how it would work with HBN then ending up with a small fortune worth of fishing flies and other gifts I decided to put the bullet sealer back.
 
I loaded for M1, M1A for years and never crimped, but these were target rounds, fired in matches or practice and only chambered one time before firing. Never had an issue w/accuracy or other.

Loaded for AR the same for a number of years before I had a bullet pushed back into the case on chambering, thus dumping some powder in the action.....what a mess!

Determined that this particular round had been chambered and re-chambered numerous times before loosening the bullet enough for it to slip back into neck.

Bought a Lee crimp die and put it in station 4 on the Dillon for all AR loading, since it is common to load the rifle, not get a shot, unload and reload same round two or ???? times before firing. As you say, the AR loads with a lot of gusto and I'm sure the bullet gets quite a workout. Haven't had an issue since started crimping.

Regards,
hm
 
With the lee crimping die case length is not quite as critical as using the crimp ring in the seating die.
 
I've got a Lee single stage press and I never felt like the Lee crimp die had any sort of consistency or solid end wall no matter how I set it.

When my buddy got a Hornady progressive press it was much better, I would still single load and weigh my hunting stuff then bring it to his place just to crimp.

Thats the only two presses I've tried to crimp but its a night and day difference.
 
I am with hm 1996 100%.

My expeerience was the same as his.

I did wonder though what the pressure rise would be if a bullet was pushed back in the case just enough to cock a bit when the trigger was pulled.

Maybe that would explain the unexplained blowups?
 
I don't crimp but the others have given good reasons to consider it.

I'll throw out that if you hunt a lot & frequently load/unload an AR without firing, you might just take that into account & make a point of shooting that round after a few times rather than just keep it in play indefinitely, if you just don't want to crimp everything.

The only rifle rounds I crimp are for lever actions, my 30-30 & 444 Marlin.

And I agree with the Lee crimp die suggestion. they seem to be well made & the ones I've had were of good fit & finish. They crimp differently than every other crimp die out there, do not require a bullet with a cannelure & case length is not as critical for them to work.
 
Originally Posted By: Kpuck08How many people crimp their loads when running a gas gun? In my .223 53Vmax loads crimping lowered my ES by about 150 fps. I getting ready to start loading for my 6ARC and curious if I should order a crimp die for it.

With the factory ammo, I can drop the bolt and load a round, then when I extract the round there are quite a few marks on the bullet. There are some marks that appear to be from the rifling as im pretty sure my barrel has a short throat, but the others are lower on the bullet and parallel with the neck of the case.

I know a crimp wont stop the markings on the bullet. Hopefully my reloads will be able to chamber and be removed with no markings on the bullets. An AR action is pretty violent though. Not sure if the Bullet can get pushed in more or when it finally slams home if the bullet slides out a bit??

Crimping can be a pain. trim lengths have to all be the same, not just within range. and just another step added to the whole process. Just trying to talk myself into it i guess.

You had a load that had 150 fps extreme spread? Something other than crimp is amiss in that load. Think about how much neck tension you have and check your expander ball diameter.
 
I am certainly not saying don't do it, but i don't crimp. I have fooled around and measured the bullet after racking several times and such over the years. I won't rack a bullet more than 2 times. After that it goes into clean barrel/fouler shot status.

If i am not sure i will get a shot, i will lock the bolt back, and put the rifle on safe and close the dust cover. Make sure you never pull the trigger with the bolt back as you can crack your lower receiver.

2 quick actions and you are firing. If it did not work out, i just pull the mag, send the bolt home and then put the mag back in.

About 10 years ago i was using TAC and Rem 7.5's. I switched to WSR primers and gained 50fps and ES went way down. Seems some ball powders are sensitive to the brand and type of primer.

Several of the loads i shoot are compressed. Bullet set back is not a worry.

If i remember correctly.....???? The bullets i measured after racking several times where getting longer, like an inertial bullet puller.
 
I don't crimp most loads and don't crimp any just because it's an AR. But crimping can help.
I know at one point I couldn't get some gold dots in 6.8 SPC to shoot very well. I had remembered reading somebody else who had issues with a load until they crimped so I tried it with a lee crimp die. It made all the difference in the world and shot great. I ended up with a hard crimp.

I tried other loads that it didn't help with so I think it can but not always. The 6.8 load is the only load I crimp.

I have a 5.56 AR that I've tried to crimp loads for and thought it worked at one point with 53 Vmaxs but when I tested the same loads again a few months later, it didn't shoot as well.

The barrel isn't great anyway so who knows. Crimping can definitely help though
 
I shoot .223, 6x6.8, 6.8, & .260 in AR's. I don't and have never crimped. But saying that I think if you do some research the 6 ARC is kind of known for bullet creep when chambering a round. Maybe you might have to crimp, especially if loading the heavier bullets. If you already have the gun you might load some up and measure after chambering. Good luck.
 
So I just measured CBTO on a factory 108 Match round, loaded one in the magazine and dropped the bolt release. Emptied the chamber and re measured CBTO… it was .005” longer. Did it again with a new round and that one was .002” longer.
 
I am interested in hearing if a Lee FCD will work for you.

Another trick is to reduce your expander ball down a tiny bit. Different companies use different material. Some brands you can easily take to much off, and others will polish only.

Of course neck tension may affect accuracy?

Seems match bullets are mostly used for target shooting anyway. I

I wonder if a lighter varmint bullet would do that?

I also wonder if it is irrelevant anyway. So long as if it grows a tiny bit, it still fits in the mag.

I chamber the round twice. After that it is no longer used for anything important.
 
Factory rds are crimped. Hand loads are often more accurate because charge weights and bullet seating is more consistent. So if you want/need to crimp, make sure it is consistent. Brass length, actual crimp applied and ogive position.
 


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