Problem w/Wolf on 16" Build

[keystone183]

Just helped a buddy rebarrel a DPMS 556 to a grendel. New 16" Faxon barrel, new gas block/tube. Gun functions fine with factory Hornaday ammo, but isn't cycling steel case. Ejects the fired case, but isn't picking up the next one. One out of about 10, it started to strip the next round but the bolt ran over it and jammed. It has what appears to be a generic carbine buffer, and a spring that was obnoxiously painted about half orange. I pulled the gas block off after about 15 rounds, and the alignment is good.

I am thinking to go a lower powered spring? I hate to open up the gas port, but would that be a better option? This guy will probably never shoot steel case, but this gun ought to be as reliable as possible and i'd like it to run right. I just helped another friend put together a complete gun with the same barrel/gasblock/tube combo with a generic PSA Kit, and it ran great. Opinions?

[VASCAR2]

[keystone183]

Was about 60* at time of firing. I did note that it looked like i was losing some gas when i pulled the block off the first time. It didn't look like much, so i was hoping that would go ahead and seal itself up. Would that be enough to cause it to be undergassed? I did clean the bcg, and lube the hell out of it, hoping that would be it, but no luck. He had probably shot a few hundred rounds of 556 previously, so it should be worn in pretty good?

[VASCAR2]

You might weigh the buffer as a carbine buffer should weigh about 3 ounces. Slight chance the buffer might be heavier. You might have got a bad batch of Wolf unless it functions properly in another 6.5 Grendel.


If I was going to use a lighter buffer spring I’d probably go with a JP silent captured spring.

[Lastrites]

Did you happen to shoot to test for short stroking with the wolf? Load one round in mag, chamber it and fire, repeat several times, bolt catch should be locking the bcg back on the face of the bolt and not the bolt carrier itself.

[Frontier Gear]

Did you happen to shoot to test for short stroking with the wolf? Load one round in mag, chamber it and fire, repeat several times, bolt catch should be locking the bcg back on the face of the bolt and not the bolt carrier itself.

Both excellent pieces of advise. The reason for the JP silent captured spring is that it comes with different springs so you can tune your rifle to the ammo that you want to shoot. They are expensive when compared to standard buffers and springs, but they do work. I have one in my Grendel. Combine that with an adjustable gas block and you would have all kinds of adjustment for different kinds of ammo.

[keystone183]

While i run JP springs in most of my guns, this is a budget constrained build! I picked up two sprinco springs, a reg. and a reduced power, and going to see where that gets me. I pulled the buffer and it weights the same as the other generic carbine buffer i had available. I did note that the spring that was in the lower seemed (totally subjective info here) stiffer and was slightly longer than either of the sprinco springs.... Will bed the gas block if this still doesn't work.

[VASCAR2]

Let us know what you find out.

[keystone183]

And the results...... Had 3 sprinco springs to try (yellow reduced power, white regular power, blue extra power). Started with the blue XP, and first shot from the mag (one round loaded) resulted in spent case ejection, but the bolt was caught on the follower but not correctly locked back. Switched white regular power, and off we went! Went through several mags no problem at all.

So, takeaway is.......DPMS used a REALLY stiff spring in this gun. Guess it helped reliability in a production rifle? Alls well that ends well....

[Frontier Gear]

Glad to hear that you got it working! Thanks for letting us know which spring worked out for you.

[VASCAR2]

And the results...... Had 3 sprinco springs to try (yellow reduced power, white regular power, blue extra power). Started with the blue XP, and first shot from the mag (one round loaded) resulted in spent case ejection, but the bolt was caught on the follower but not correctly locked back. Switched white regular power, and off we went! Went through several mags no problem at all.

So, takeaway is.......DPMS used a REALLY stiff spring in this gun. Guess it helped reliability in a production rifle? Alls well that ends well....

Thanks for posting your results, might help another forum member in the future!