Do you think this could be a problem?

[1903Collector]

When I got my 6.8 upper from Bushmaster a few weeks ago I took it out to the range and had all kinds of trouble.
http://northeastshooters.com/vbulletin/showthread.php?t=30703

So I take back out today and it still seems like it is short cycling, the carrier is not coming back enough. The only ammo I have been able to find is Hornandy. I went thru two magazines with no jams, but it would not strip a cartridge from the mag and the bolt carrier does not stay open after the last shot but it will if I manually retract the carrier. So I get home and take it all apart and while I'm cleaning I notice these marks:
View attachment 940
View attachment 941
None of my other ARs have these two marks and when you run your finger over the area it feels like it steps up just a little. You can also here the carrier rubbing/grinding against something. Now I am comparing to my four other ARs, no marks and no rubbing. It's as if it was not completely milled or milled incorrectly. No IF that's the case could that cause the carrier to be sluggish? The carrier moves back and forth easily but I'm just wondering if that could cause the trouble I am having.

Thanks
Walter....

 

[vellnueve]

That could potentially slow the carrier down a bit, but I'm not sure it would be enough to short stroke the rifle. Are you sure you're using the correct buffer tube/spring combo?

Hard to tell by just looking at a picture.

 

[1903Collector]

I think so, it's the standard buffer and spring but I bought the lower seperate from the upper. Perhaps it uses a different one. I am contacting Bushmaster this week and hopefully they will have an answer.

 

[vellnueve]

Well, I know the stuff in a CAR stock is different from a regular A2 stock.

 

[Joe R.]

I'm not gonna remember everything so I'll have you look for it. Type in " 6.8 SPC " into Google and read until you can't see straight.

Joe R.