AR buffer fore fire-forming

[miningshawn]

My AR will not fully cycle when fire-forming .223 AI loads. I am assuming that a lot of energy is being used to form the brass. I have a Seekins adjustable gas block at wide-open.

The rifle works great with full power .223 AI, it is just a pain to fire-form and rack the charging handle.

I have a standard carbine buffer - I really haven't found anything lighter for spring\buffer assemblies (easy to swap in and out when fire-forming). I am sure there is something out there.

The rifle is perfect when running AI loads:
- 25.9gr Varget, 77 Berger OTM, Starline, CCI-BR4.
The fire-forming loads just don't have enough "oomph"
- 25gr R10x, 55gr Speer, Starline, CCI-BR4

So, I can't increase gas. The barrel is 24" and the gas tube is rifle length. I am hesitant to cram more powder in the fire-forming load. I am hoping a lighter buffer\spring will do the trick. Any suggestions?

I have also tried XM193 and it cycles 50\50.

 

[msinc]

This is pretty easy and believe it or not it's even in the Army manual, or at least it used to be. Get another buffer spring and cut coils off one half at a time until it cycles. It really is that simple. Mark your new "fire form" spring with a swatch of paint. Drop it in when forming, take it out when not.
The gas system in stock form is not adjustable, yours is and it's as wide open as it can go...only thing left is the spring....I have done this since 1981, zero problems. I would also suggest you do your fire forming with full power 223 rounds. I have several Ackley caliber rifles and have never used any special different loads to fire form my brass.

Edit: one more thing...since this weapon has a replaced, or non factory gas block it might be a good idea to stick a borescope down the bore and have a look at the gas port alignment. You can easily see if the barrel port is in perfect alignment with the gas block. If not, loosen the gas block and adjust....one more reason every shooter should own a borescope!!!! They make a one piece continuous "spira-lock" gas seal that goes on the bolt and replaces the three factory seals {and their three gas leaking gaps}. Shouldn't need this, but if you really want maximum gas seal.....

 

[jepp2]

I do a lot of fireforming, just not in AR's. But I shoot AR's a lot. I would just increase the load until the rifle cycles properly. Max loads in the parent cartridge, is recommended for fireforming. Is there a reason why you don't want to increase the powder? You could always take some weight out of your buffer. But I would increase the powder.

And I'm assuming your gas rings aren't worn.

 

[mikehotel]

pretty much what music said. However I first would swap in a flat wire buffer spring. The other thing that you can do, is purchase the JP enterprise captured spring and spring kit.

https://www.midwayusa.com/product/7...red-recoil-buffer-spring-assembly-gen-2-ar-15.

https://www.midwayusa.com/product/4...or-ar-15-silent-captured-spring-recoil-buffer

 

[miningshawn]

I do a lot of fireforming, just not in AR's. But I shoot AR's a lot. I would just increase the load until the rifle cycles properly. Max loads in the parent cartridge, is recommended for fireforming. Is there a reason why you don't want to increase the powder? You could always take some weight out of your buffer. But I would increase the powder.

And I'm assuming your gas rings aren't worn.

25gr of R10x and a 55gr speer are already over max in 2 of my 3 loading books; and, to much more powder and I would be using a drop tube. So.... laziness on my part. I was also thinking of a faster powder that is cheaper than Varget or CFE223 if you have a suggestion. Thanks!

 

[miningshawn]

This is pretty easy and believe it or not it's even in the Army manual, or at least it used to be. Get another buffer spring and cut coils off one half at a time until it cycles. It really is that simple. Mark your new "fire form" spring with a swatch of paint. Drop it in when forming, take it out when not.
The gas system in stock form is not adjustable, yours is and it's as wide open as it can go...only thing left is the spring....I have done this since 1981, zero problems. I would also suggest you do your fire forming with full power 223 rounds. I have several Ackley caliber rifles and have never used any special different loads to fire form my brass.

Edit: one more thing...since this weapon has a replaced, or non factory gas block it might be a good idea to stick a borescope down the bore and have a look at the gas port alignment. You can easily see if the barrel port is in perfect alignment with the gas block. If not, loosen the gas block and adjust....one more reason every shooter should own a borescope!!!! They make a one piece continuous "spira-lock" gas seal that goes on the bolt and replaces the three factory seals {and their three gas leaking gaps}. Shouldn't need this, but if you really want maximum gas seal.....

I was hoping for this answer or one just like it! Thanks! I don't have a borescope - but I know someone who does and that will also be on the to-do list. I have been trying to stay at or under max load in the Sierra and Hornady books but I may have to go to a compressed load if the spring doesn't fix it. The action is a new DPMS with less than 200 rounds. I haven't seen any real leakage past the rings yet and the action is relatively (compared to my Sig 516) clean after fire-forming 100 plus cases.

Thanks for the advice! I will be taking this to the bench.

 

[miningshawn]

pretty much what music said. However I first would swap in a flat wire buffer spring. The other thing that you can do, is purchase the JP enterprise captured spring and spring kit.

https://www.midwayusa.com/product/7...red-recoil-buffer-spring-assembly-gen-2-ar-15.

https://www.midwayusa.com/product/4...or-ar-15-silent-captured-spring-recoil-buffer

Ordered the second. Thanks for the great link!

 

[10at6]

Wrong powder. just load a standard 223 load.. Like 25 gr of varget with a 69 and try it

I have FF 1000s of 223 ai in an AR. Always used h4895 with or Varget near max loads. Lots of them with 55 gr Vmax.

ARs don't like to function with really fast powders

 

[msinc]

This is kind of a quick check test for the gas system you can do easily if you have access to compressed air and a rubber tip blow gun. Remove the upper and place either a fired case in the chamber and close the bolt and carrier {obviously it needs to be a case that was fired in this chamber...} or you can use a resized case {just be sure it has a primer installed} or loaded round if you want. Plug the blow gun tip into the muzzle and pop it with about 100 psi of compressed air.
It should at the very least pop the carrier back and unlock the bolt. If it does not you can hit it with more air and sometimes hear where air is leaking. It will not blow the bolt open and eject the round so don't worry if it doesn't. If it seems like no or not much air is leaking then you really need to have a look at the gas port to block alignment. This is really not any kind of formal "accepted" test, but it has proven valuable to me over many years.
Note: Don't remove the firing pin if you are using a live round...it cannot fire and the system needs the firing pin in place to make a gas seal so the system will work.

Edit: rubber tipped blowgun only...do not try to do this with any kind of metal tipped air nozzle...even if it looks like it's made out of brass. It's probably made in China plated steel!!! You cannot take a chance on gunching up the rifling at the muzzle!!!

 

[jepp2]

if you have a suggestion

I did most of my 223 AI fireforming using Speer 52 gr HP's (I buy the bulk 1000 packs and they are pretty cheap) along with WC 844 Powder (the bulk pull down grade of H335). No problem with case capacity and it made an accurate load that sent a lot of prairie dogs to their next life.

 

[akajun]

They make different weight buffers for ar’s you can kind of do it yourself by driving the roll pin out of the buffer , removing the rubber plug, and removing some of the shot or weights inside. Then replace the rubber and roll pin. If you have a lathe you can even take metal off the buffer to get it lighter.
I’d do that before cutting springs. In my armorers class we were always taught never cut / modify the spring, change/ modify the buffer.

 

[MGYSGT]

You don't say how big the hole in the barrel gas port is. I have a rifle length that just wouldn't cycle. The hole was 60 thou and I drilled it to 80 thou. Problem solved.