Anybody else use a 9mm buffer in a .223

[Hang-Fire]

I have a 11 inch .223 upper for my SBR. It has been short stroking occasionally to the point that it has aggravated me pretty badly. I had read that a heavier buffer might help the situation. Today I tried using the buffer out of my 9mm rifle. The .223 functioned perfectly.

HF

[Stickman]

Make sure it runs with all of your different types of ammo. Under powered .223 tends to cause the most problems, but I run one that way and have had great results.

[Robb Jensen]

I have a 11 inch .223 upper for my SBR. It has been short stroking occasionally to the point that it has aggravated me pretty badly. I had read that a heavier buffer might help the situation. Today I tried using the buffer out of my 9mm rifle. The .223 functioned perfectly.

HF

It all really depends on your gas port size. If you know it's diameter, I can better tell you what buffer you should run.

Generally speaking smaller port = lighter buffer / large port = heavier buffer.

Also be sure to check your carrier key for leakage and proper staking and make sure your rifle is properly (meaning generously) lubed.

If you're 100% sure that the carrier key/gas block/gas tube isn't leaking running a heavier buffer than you may now have will only compound the problem. The test for short stroking is easy. Take several mags (at least 10) and load only 1 round per mag. Take 1 mag at a time and fire the 1 round. It should lock open everytime.

If it doesn't lock back you can be over buffered/sprung, have a gas leak or very weak ammo or on some occasions not locking back can be a weak mag spring that can't lift the bolt catch fast enough before the bolt is going forward again.

This is the problem with HK mags in ARs (as the mag ages and becomes weaker). Some very fast cycling ARs can have the bolt 'outrun' the HK mag. The mag simply can't keep up. Use known good mags for testing.

On rare occasions not locking back can be a bolt catch issue.

If going to a heavier buffer (than what you were using) fixed your problem you may need new mag springs/followers or just new mags. Theory being that slowing the cyclic rate allowed the mag more time to lift the bolt catch to lock open the bolt when it ran dry.