I have an Oly Arms/Dalphon 9mm upper on a Grizzly lower. Mags are either Oly midified Sten or unmodified sten with a KKF/Socom mag block. Stock is a 3 position fiberlite with a standard buffer system.

Problem:

Whenever I shoot Wolf ammo thru this rifle, it goes full auto. The first 3 rounds are semi and then it just goes full auto expending 4 to 5 rounds before jamming on a spent casing which failed to eject all the way. If I use any other ammo, Winchester white box, PMC, Remington, UMC, the rifle functions normally. However, it seems to want to perform different with Wolf.

Any ideas?

Could it be the buffer or the fact that it may need a 9mm hammer?

taking a WAG here.  maybe it's underpowered and not resetting the hammer, but going back far enough to eject case.

possible the finish off the case 's are hanging up the f/pin and slam firing. OR the wolf's primer's are sitting higher?

Well, another thing I noticed: WHen I insert a loaded mag (Wolf ammo) and I release the bolt, it slam fires the first round chambered. Not always...just sometimes. It doesn't do it with the other ammo mentioned.

You don't need a 9mm hammer in an OLY and the standard buffer is ok. My OLY started doubling/tripled after I had used about a case of Wolf pretty dirty stuff. I noticed that my firing pin was stuck for lack of a better word. Soaked the entire bolt in Hoppes, then cleaned and relubed bolt and firing pin.  Since then I have run 7-8k of various ammmo through it no problem.

Quoted: You don't need a 9mm hammer in an OLY and the standard buffer is ok. My OLY started doubling/tripled after I had used about a case of Wolf pretty dirty stuff. I noticed that my firing pin was stuck for lack of a better word. Soaked the entire bolt in Hoppes, then cleaned and relubed bolt and firing pin.  Since then I have run 7-8k of various ammmo through it no problem.

Thanks for the input Bob. I'll do a permanent change and see if that helps

Does Oly send out it's newer uppers with the firing pin spring?