Hello everyone, new guy here from Maryland

I recently built my first AR. not first owned, but first built. took it out to the range and it seemed to run fine on PMC XTAC brass 5.56, but had some double feed issues with the steel tula .223. My question is how do I tune this thing to run on the cheap stuff? Do I need to just wait and break in the rifle further? I only had time to run 40 rounds of brass and 30 steel through it so far. I cleaned after the first round for up to 5 rounds and then 3 shot groups then cleaned up to around 30 rounds. The specs are below. Do I need to tune the buffer and spring combo? any advice is much appreciated.

spikes lower receiver
spikes upper receiver
spikes phosphate bcg
stag arms 20" hbar barrel (1/9 twist, chrome molly, 4140 steel, and rifle gas length)
geissele SSA-E trigger
spikes LPK
standard a2 buttstock/spring/buffer I had from my colt hbar sporter previously owned but very lightly used (less than 500 rounds)
BCM charging handle (medium)
Midwest industries 15" gen 2 SS series FF handguard
Midwest industries low profile gas block
gas tube from stag arms
standard a2 flash hider from stag arms

thanks in advance for the input. I'll post pics once I figure out an image hosting site. any suggestions on that?

double feed is usually a mag problem, ie two "live" rounds



double feed in which a shot round is not extracted and a loose "live" round is a ejector/extractor or gas problem



if its a gas problem, shoot one round, does the bolt lock back? =yes then not a gas problem



shot round, over a live round=does the steel cases get flung as far as the brass ones, prob a ejector.



if the rounds are gettting ejected with the same force (hand cycle some in a safe direction to see) then its a extractor/spring issue.





Other than that it could be anything with your description.



 

Ok so my plan is to label my mags and document which ones if any give me issues. Thanks for the reply. I looked at the video I took and all shell both steel and brass were being ejected at 3 o clock

And forgot to mention that the bolt does lock back after the last round is fired

Are you using proper amount of lubrication?

Tula runs like crap in my 20" when it start drying out from lack of lube but Wolf and Brown Bear run 100%.  Tula is the lowest of the Russian steel ammo.

Yes I pretty much have my bolt dripping with hoppes gun oil

Hard to diagnose based on this, but if it works fine with most things other than Steel case then that should be self explanatory I'll take a stab at it:

It's possible the extractor could be an issue, but shouldn't be on a new BCG with what 70 rounds through it?

Geissele shouldn't cause any problems, so that takes care of that.

Buffer and Buffer Spring with a low round count shouldn't cause problems but anything is possible

Gas Port could be an issue

I'm just here to beat on you for not posting the obligatory pictures....

It doesn't lock back with either types of ammo, or just the Tula 223?

If it works fine with PMC 5.56 and chokes on the lighter Tula load, that's not ultra uncommon, but not desirable if that's what you want to shoot.  If that's the case, make sure you have a perfectly functioning gas system, then you can drop down a buffer weight to shoot the lighter stuff.  

If, however, you're BCG doesn't lock back after the last round with the 5.56 load, then you have a gas system issue.  Did you remember to leave the handguard cap gap between your gas block and barrel shoulder (assuming you have one), or did you push the gas block all the way back against the shoulder?  If you did, the ports are probably not lined up and that's your choke point.  If not, then more info is required, as these things can be tricky to diagnose via the interwebz.

http://i36.photobucket.com/albums/e4/brianmcgrath1978/Mobile%20Uploads/20140923_150208_zpstl3fusqy.jpg

It locks back with both kinds of ammo

<a href="http://s36.photobucket.com/user/brianmcgrath1978/media/Mobile%20Uploads/20140923_150208_zpstl3fusqy.jpg.html" target="_blank"><img src="http://i36.photobucket.com/albums/e4/brianmcgrath1978/Mobile%20Uploads/20140923_150208_zpstl3fusqy.jpg" border="0" alt=" photo 20140923_150208_zpstl3fusqy.jpg"/></a>

Which link do I copy and paste to get the pic in the thread?

http://i36.photobucket.com/albums/e4/brianmcgrath1978/Mobile%20Uploads/20140923_150208_zpstl3fusqy.jpg

DOES lock back.  Reading comprehension fail on my part.  The rest still holds true.

I just re read the above post. Theres supposed to be a gap between the gas block and barrel stop point? I thought you slid the block down to the ridge it stops on?

What kind of gas block do you have? If the gas block is pinned there should be a part of the barrel drilled/machine out for the pin.  That's the easiest way to know if the gas block is in the right place, assuming the barrel maker properly installed it.

Yes, typically .025, which is left there because the FF rail system you're now using does not require the hand guard cap which normally butts up against the barrel shoulder.  

Here's an exert from JP gas block installation instructions....

"The JP gas block is designed to replace a standard military front sight assembly. If you have installed a free floating hand guard on a military spec barrel, there will be approximately a .025” gap between the back of the gas block and the shoulder on the barrel. This gap is where the forward hand guard retainer would fit if you were using a military hand guard. This gap is important because it assures proper gas port-to-gas block alignment..."

http://www.jprifles.com/document_pdfs/JPGS5_521.pdf

Start with using only USGI or magpul mags.  I think those are the two best.  Either way, mags can cause double feeds and not lock the bolt back.  Although weak ammo could also not lock the bolt back or some kind of sluggishness on the rifle's part.  But start with the mags.