Recommend Weak Ammo to Test for Short Stroking

[Gideon]

I just assembled a new carbine AR-15 in which I used a Tubb chrome silicon buffer spring. The spring only comes in one length for both a rifle and carbine length receiver extension. I have read that at least 3 coils should be removed for the shorter carbine tube that I am using, but I decided to see how the full length spring felt. Whoa ..... alot of force required to work the charging handle. Press the bolt release (if you have the strength to do so) and it felt like you were tripping a coyote trap in your hand. So, with a dremel tool outfitted with a cutoff wheel, I lopped off 3 coils. Still alot of force there but at least now I'm ready to start testing if more coils need to be removed. (To complicate matters, I have an adjustable gas block.)

The test will be to fire the weakest ammo I would ever use while limply holding the rifle away from my body, so just the inertia of the gun will be absorbing the recoil energy. When fired this way, I want to ensure it doesn't short stroke. What ammo do you recommend for conducting this test and do you think the test is a good one?

 

[jakerz3]

Re: Recommend Weak Ammo to Test for Short Stroking

Tul ammo. I would personally just run a standard spring and a 3oz buffer.

I've had to play around with some different buffer weights to get my middie running right. But I never really messed with the spring.

 

[TonyAngel]

Re: Recommend Weak Ammo to Test for Short Stroking

Yeah, if it's going to fail, it will likely do it with Tula.

 

[leadbullet]

Re: Recommend Weak Ammo to Test for Short Stroking

tula or wolff 62 gr, anemic.

 

[Gideon]

Re: Recommend Weak Ammo to Test for Short Stroking

I ended up just reloading some rounds at the recommended "starting" powder charge. For me, this meant using 24 grains of H4895 behind a 60 grain Hornady V-Max. (My final load is 25 grains with that bullet.)

Here's what I did. I removed 3 coils from the Tubb buffer spring since I'm using a carbine receiver extension (buffer tube). I then opened the adjustable gas block to its most open position. I loaded a single round into the mag and fired it to see if the bolt would lock back on the now empty mag. I continued doing this one round test with the gas block closed off by a full set-screw turn between tests. It wasn't until the gas block was nearly completely closed off that the action short-stroked and failed to lock open. I then opened the gas block a half turn and called it quits for now. My full strength loads of 25 grains of H4895 with the 60 grain bullet operates very smoothly. I conducted the test using a normal hold on the rifle, with the butt against my shoulder.

 

[50APIT]

Re: Recommend Weak Ammo to Test for Short Stroking

As a few have mentioned, the wolf/tula ammo is probably the weakest commercially availble ammo. To accurately test your worst case scenario, you should do the test at the end of a range session when the rifle is fairly dirty as that is when it would be most likely to short stroke.