Hello everyone,

I am new to the forum and also new to SBR's but I am familiar with the AR platform.(But likely not nearly as familiar as many of you)
First I will give the background of the rifle and the parts I used and then I will try to explain the problem in detail. I apologize if this has already been covered elsewhere but I am new to this forum and I am still getting used to it.

My rifle started out life as a STAG Arms Model 2TL(I AM LEFT HANDED)
I shot it for years and I never had a problem. It always shot virtually every type of ammo I have ever fed it. When I finally got my tax stamp I was happier than a pig in slop. I went to work turning my rifle into an SBR. I added an DPMS 11.5 inch Heavy barrel with a 1 in 9 twist rate, a longer Samson rail, low profile gas block under the rail, and an H3 Buffer. The gas system is still a direct gas impingement carbine length setup.
It shot fine this past Sunday with 3 types of factory made brass cased ammo, but it had issues with the steel cased Wolf ammo. All of the ammo was 55 grain. Some of the brass cased ammo was 5.56 surplus and some was .223 spec. The steel cased ammo was .223 spec. Here is what went wrong: When I shot the steel cased Russian ammo, the bolt failed to cycle all the way back resulting in a jam. There were NO failures to extract. I just failed to cycle the full distance rearward and load another round. I have already ruled the magazines out as a source of the problem. I suspect that the Russian ammo is not hot enough to cycle the bolt with an H3 buffer. If this is the case, which buffer weight should I use? H1 or H2? Are there any other possible causes?

Thank you for any help you could provide and I am glad to join the forum.
http://i850.photobucket.com/albums/ab62/davissp2/SDAVIS-PC/Guns/fc13c362-4225-48d2-b3e4-c25f565d37f5_zps914b4c3f.jpg?t=1386813212

Thanks, I'll try the carbine buffer. Do you think it might be too light for an SBR?

Wolf and Tula are both notoriously underpowered.

You also have an oly arms barrel which is pretty much bottom of the barrel quality wise.  Who knows what the gas port size is.

Whats wrong with oly barrels? I am not looking for long range sub moa accuracy from an sbr. My intent is to use it for carbine courses, truck gun, and just for fun. I like the really heavy profile because I shoot high volumes and I like to shoot fast.

I justed edited the first post. It is a DPMS 11.5 inch heavy barrel not an Olympic Arms barrel.

Here is a link.

http://www.midwayusa.com/product/683239/dpms-barrel-ar-15-pistol-556x45mm-nato-heavy-contour-1-in-9-twist-115-chrome-lined-chrome-moly-matte-with-front-sight-tower-pre-ban

You do not need to use HBs in any rifle that has its gas port set up correctly.  The only use for HBs IMO is to slow things down when the rifle is over gassed to begin with.  Now that you have another barrel on there, very likely it is gassed correctly (DPMS has been doing this for decades) and now your 3HB combined with lower powered ammo is too much for it to overcome.  My recommendation is to go back to the standard buffer and see what happens.  Check your ejection position and then if you feel you need to increase buffer weights increase one weight at a time, ie, standard to HB, then to 2HB…
Starting out with a 3HB is like trying to fix something before you even know if it is broken.

Well,

I second that...

Put the standard buffer in there...see where your at...

I tune a lot with buffers, and your running a carbine gas system...the gas port is still at the same distance from the bolt...

With a new barel you should always start back at the basics first, the tune from there...

B