AR FTFeed issue

[pwer lineman]

Hi All!

I'll get right to it. I just finished my first AR build. Stats: 18" barrel with rifle length gas system, milspec upper, m16 bcg, standard lower, and lower parts kit. carbine buffer tube, spring, and buffer. I just finished it today, and took it to the range for a full run out. I started off shooting PMC Bronze .223, and I shot 20 rounds with a failure to feed almost every round. Happened to have some xm193 5.56 in my range bag, and 60 rounds of that later, no problems. 1 more box of PMC, same issue.

so heres the question. Do I need a different buffer? buffer spring? what is the likely culprit here?

thanks for all the help

[atdski07]

You have rifle length gas system with carbine buffer assembly

[atdski07]

With that said you are going to have trouble shooting bargain ammo, the 5.56 produces more pressure than the budget .223, I had the same problem, I changed the buffer assembly and it works great now, the buffer assembly I had was an ATI kit and after the fact I found that many people have problems with the ATI buffer kits. Also lube the bejeezuse out of you bcg, run that baby wet, they like it wet

[baih777]

You have rifle length gas system with carbine buffer assembly

+1

I would install the correct buffer and tube. And yes you will need a new stock.

[pwer lineman]

So I have to run an A2 stock?
What other options are there? Can I find a new buffer tube/spring/buffer that will accept the STR stock I bought?

Matt

[atdski07]

I believe rifle buffers weight more but have a softer spring, and it is the opposite with the carbine, lighter buffer with stiffer spring

http://4-riders.com/pics/AR/buffers.jpg

[pwer lineman]

Thanks for all the info so far! If anyone has any knowledge if where to pick up an adjustable stock for a rifle system, please share. I'm using the crap out of google, and have come across vltor, but no solid info.


Matt

[isplice]

Your likely culprit here is the soft shooting PMC ammo. As for an adjustable stock with a rifle length gas system, google Canadian C7A2. it seems to work for them.

[a308garand]

The thing you have discovered is that PMC ammo can test the limits of your gas system, its kinda on the weak side- but not as bad as Wolf.

Go over the entire rifle to ensure no gas leaks. Gas rings on the bolt, gas tube aligned in the bolt carrier without drag, gas key bolts tight, etc.

Make sure the rifle is lubed up with enough oil. Run good quality ammo (at least 200-500 rounds) to break in the moving parts. Once the rifle gets broken in, the PMC ammo may start to run. The bolt/barrel extension become married and excess friction goes away when the parts are fitting perfectly.

If you really want it to run PMC and Wolf ammo, it may require the gas port to be slightly opened up a size. This will flood much more gas into the system and force it to run. Your 18" barrel is not giving the system enough dwell time like a 20" barrel would. If you had a carbine or mid length gas system on the 18" you may have a better performer.

[pwer lineman]

thanks for the thoughts. I'll try breaking it in before I do anything else. I saw the Vltor A5 buffer set up last night, but i'm going to wait on that..

[ott1]

Why not try a lighter buffer spring before going about opening up the gas port?

[a308garand]

Why not try a lighter buffer spring before going about opening up the gas port?

A lighter weight buffer spring may allow too much bolt carrier travel.

The recoil spring gets compressed to a certain point and its length prevents parts from bashing into other stuff.

If too short or worn out...The gas key can smack the rear of your receiver, the back end of the buffer can smack into the rear of the buffer tube, the bolt carrier may not have enough forward force to put the bolt into battery...

Opening the gas port is a last resort. A lighter weight buffer in an carbine receiver extension could help. (carbine buffer and an older SP1 type bolt carrier could make a change for the better)

[ott1]

I think a lighter weight buffer spring is a better option than opening a gas port. Once you open up the gas port, there's no going back unless one gets an adjustable gas block. At least if the spring doesn't work, one can go back to the original spring/buffer setup.

[pwer lineman]

What is lighter than a standard carbine buffer? All the ones I saw were heavier


Matt

[alucky1]

If you find the A5 system anytime soon, send me a message. I've been looking, but haven't had any luck finding it anywhere. Thanks