Crimp Test In AR

[Walt Krafft]

Neck tension is determined by the amount the bullet has to open the neck and the hardness state of the brass. Crimping is a bandaid to get uniform pressure when not controling the basics. Mag length ammo in an AR will shoot just fine with no change in accuracy without a crimp.

 

[jepp2]

I stopped annealing for gas guns, didn’t see the results on paper or seating enough to matter for my uses and amount of firings I get out of my brass (pockets get loose).

Our philosophies couldn't be further apart. When I stay below the SAAMI max pressure, primer pockets never loosen. I did a case life test just to see how many firings they would last, and what would cause them to be retired. In my test, I got 24 to 35 firings, and the cause of retirement was nicks in the shoulder/neck regions from ejection contact with a barrel locking lug on a barrel I had just installed. I now take the sharp point off the lug and the problem went away.

Regarding need for annealing, the necks will work harden rather quickly and with your 0.006" neck tension reduction from your honed die it will exacerbate the amount of work put into the neck each firing cycle. Maybe your improvement from crimping, is due to the hardened case necks from the lack of annealing.

Just sharing an alternate view on the world.

 

[Cfshooter]

Our philosophies couldn't be further apart. When I stay below the SAAMI max pressure, primer pockets never loosen. I did a case life test just to see how many firings they would last, and what would cause them to be retired. In my test, I got 24 to 35 firings, and the cause of retirement was nicks in the shoulder/neck regions from ejection contact with a barrel locking lug on a barrel I had just installed. I now take the sharp point off the lug and the problem went away.

Regarding need for annealing, the necks will work harden rather quickly and with your 0.006" neck tension reduction from your honed die it will exacerbate the amount of work put into the neck each firing cycle. Maybe your improvement from crimping, is due to the hardened case necks from the lack of annealing.

Just sharing an alternate view on the world.

I’m guess my loads are on the hot side, and or brass sucks lol (starline/norma/lc).

Annealing did help necks from splitting. I would start to see split necks around firing 4-6 without annealing and pockets loosen up around the same time for me. That’s when I said no more annealing the gas gun cases.

When I did anneal, I didn’t make it to split necks before I started to see some pocket issues. Once I would get a case or two from a lot to start show loose pockets, the next load or to they would be retired. I’m fine with 5-6 firings for my gas gun brass, it does its job for the cost.

 

[jelenko]

24 to 35 firings

Wow.
I don't anneal. Split necks start showing up around 4th or 5th firing. I cull these and incipient case separations until the primer pockets open up. I usually get 7-8 firings on LC 223 brass.
My loads are all 7-8K psi under SAAMI max

 

[jepp2]

I cull these and incipient case separations

This is how I expected the end of life to occur on the cases, due to the amount of shoulder movement and setback for a gas gun. What I found was after 10 firings, I never got any material removal when I trimmed. My process was to inspect cases after firing, size with at least 0.003" shoulder setback, trim, paperclip test each case every firing, and anneal every 5'th firing. No cases showed any thinning near the base. Here is why I retired them.

 

[Cfshooter]

This is how I expected the end of life to occur on the cases, due to the amount of shoulder movement and setback for a gas gun. What I found was after 10 firings, I never got any material removal when I trimmed. My process was to inspect cases after firing, size with at least 0.003" shoulder setback, trim, paperclip test each case every firing, and anneal every 5'th firing. No cases showed any thinning near the base. Here is why I retired them.

View attachment 1572207

You got your money's worth for sure!

 

[jelenko]

This is how I expected the end of life to occur on the cases, due to the amount of shoulder movement and setback for a gas gun. What I found was after 10 firings, I never got any material removal when I trimmed. My process was to inspect cases after firing, size with at least 0.003" shoulder setback, trim, paperclip test each case every firing, and anneal every 5'th firing. No cases showed any thinning near the base. Here is why I retired them.

View attachment 1572207

Yeah. I get those also. When I retire the lot, none go all the way through. It looks like the one in the center is going all the way through.

 

[Hudge76]

I did a similar test and had to end it early due to having to leave the range. I plan on redoing it, but all I got was minimal from what little I did test. Mine were all down with my “plinker” AR load.

 

[Cfshooter]

I did a similar test and had to end it early due to having to leave the range. I plan on redoing it, but all I got was minimal from what little I did test. Mine were all down with my “plinker” AR load.

Mine were all done with a "plinker" load also. I did not see much, but I do seem to see something every time I have done this type of test in an AR. Nothing earth-shattering, but looks to add a touch more consistency.

 

[markm87]

I did a similar thing years back, and I had 77 SMKs that shot a lot better with the Lee FCD. Repeated the test last year and couldn't tell the difference.

I still run the FCD on all .223 ammo... bolt gun or not.

 

[Hohn]

Here are the groups from some crimp testing. Not a huge difference, just seems to limit the “gas gun flyers” a bit more. This is just a bulk load for plinking and the top set was loaded using the Lee 4-hole turret press and the powder was dropped by a case-activated dropper. I think I have a new way to load plinkers.View attachment 1571278

Guessing that if you did the math, there’s about a 90% chance you’d get this with random samples of the same population. Heck, one might conclude from your middle bottom group that no crimp shoots tighter.

It’s just too small a sample with too much variation to conclude what you think this shows.

 

[misser]

never found a good reason to crimp with the 223 , how ever the 708 LR 10 is a different story. I found the bullets would move out a few K when the BCG slammed closed . the fix was to crimp .if the bullet did not have a cannelure I put one in .

 

[Coyotefurharvester]

I anneal all my 223/556, size to the drop fit Lyman ammo checker as I may use in several bolt/ gas guns. Uses plinking, coyote/fox hunting, prairie dogs. My winter gas gun brass gets an extra 0.0005-0.001 shoulder bump, as I want no issues loading from mag in subzero temps. Or unloading live rds. And I do see bullet movement loading from mag(bolt release lever) with my 20p, I use a -0.002 mandrel. And light crimp after seating this stops the momentum bullet movement. Allowing me to return unfired rd to top of mag with no function(safety) or accuracy concerns.

 

[Cfshooter]

never found a good reason to crimp with the 223 , how ever the 708 LR 10 is a different story. I found the bullets would move out a few K when the BCG slammed closed . the fix was to crimp .if the bullet did not have a cannelure I put one in .

That’s a bunch of mass on those large frames.

 

[Cfshooter]

Guessing that if you did the math, there’s about a 90% chance you’d get this with random samples of the same population. Heck, one might conclude from your middle bottom group that no crimp shoots tighter.

It’s just too small a sample with too much variation to conclude what you think this shows.

For sure, very small sample size and doesn’t show too much. I have done similar tests over and over again in the past and always seems like very minimal results, but knowing my bullet isn’t changing seating depth while chambering is one less thing I have to chase in this crazy quest lol.

 

[misser]

For sure, very small sample size and doesn’t show too much. I have done similar tests over and over again in the past and always seems like very minimal results, but knowing my bullet isn’t changing seating depth while chambering is one less thing I have to chase in this crazy quest lol.

ever get flyers ?

 

[Cfshooter]

ever get flyers ?

Oh, for sure. But not near as often with a good load and barrel. It does seem like less “flyers” with the gas guns with some crimp though. It’s really just more just piece of mind that my depth didn’t just change when the bcg flew home.

 

[Hohn]

That’s a bunch of mass on those large frames.

Indeed, which is why you should let them feed from the mag— it slows it down enough to tame it somewhat.

 

[Andy Legg]

My two son’s and myself have been using the Lee FCD on all our .223 Match Loads that we shoot in Mid and Long Range Prone AR Tactical Matches. I Noticed much tighter SD’s when we started sorting brass & tracking number of reloads on the brass and using the Lee FCD.

Our 77 SMK 8208 xbr competition loads (1460 fps @ 600 yds w/11.9 SD) are pretty hot compared to a very accurate milder load of Varget with the same bullet (1376 fps @ 600 w/9.8 SD)..….both are very accurate loads….the faster load seems to do better (win matches) in the wind.

I attribute the low SD’s to consistency with reloading practices and the Lee Factory Crimp Die with a very light but constant crimp. I realize we are likely being lazy by not meticulously setting neck tension with a bushing seating die….but this is simple, quick, and it works for us. Also, this was loaded on a Lee Turret Press.

Note: Although we are shooting AR’s, Mid/Long Range Prone Competitions require all rounds be Single Feed (but a magazine must be in the rifle-No Sleds Allowed).

Andy Legg.

 

[Cfshooter]

My two son’s and myself have been using the Lee FCD on all our .223 Match Loads that we shoot in Mid and Long Range Prone AR Tactical Matches. I Noticed much tighter SD’s when we started sorting brass & tracking number of reloads on the brass and using the Lee FCD.

Our 77 SMK 8208 xbr competition loads (1460 fps @ 600 yds w/11.9 SD) are pretty hot compared to a very accurate milder load of Varget with the same bullet (1376 fps @ 600 w/9.8 SD)..….both are very accurate loads….the faster load seems to do better (win matches) in the wind.

I attribute the low SD’s to consistency with reloading practices and the Lee Factory Crimp Die with a very light but constant crimp. I realize we are likely being lazy by not meticulously setting neck tension with a bushing seating die….but this is simple, quick, and it works for us. Also, this was loaded on a Lee Turret Press.

Note: Although we are shooting AR’s, Mid/Long Range Prone Competitions require all rounds be Single Feed (but a magazine must be in the rifle-No Sleds Allowed).

Andy Legg.

Thanks for the great info Andy, much appreciated. I really like hearing you load your match loads on the turret, good stuff! I just loaded up a batch of 69SMK plinker loads on the turret and was surprised how well they shot. I am now setting up a turret plate for 22 arc lol. If the arc does well, I will try it out in my next mid range prone match.