AR-15 failing to feed and gouging bullets, help!

[eod.mickelson]

Okay, first, this is a Seekins rifle and I know they'll take a look at it and have amazing customer service, but I'd prefer to not have to part with it for now.

Just picked up a new to me seekins SP15 DMR, 700 rounds on it from previous owner. Previous owner is very trustworthy and had no issues with it.

I have been having issues with feeding, about 25% of the time. I'll attach photos but it seems like the rounds are getting stuck on the feedramps. I have felt the feed ramps and don't feel burrs, I lightly went over them with an Emory cloth and there was no change.

I also noticed that ejecting a live round, no matter which side of the mag they feed from, the projectiles are gouged.

Is this a mag problem (tried a 40 rounds, 30 round, and 10 rounds pmag)? Is there anything I'm missing that could be causing this?
Thanks!
Dan

 

[cohunt]

Yup- don't use pmags-- try a metal mag--- most likely the feed lips of the mag need to be tweaked so the bullet presents itself at a "nose up" angle-- you can't really tweak the feed lips of a Poly mag, that's why I like metal mags-- and to add more- SS mags are thinner so you can load longer too if handloading

If your feed ramp needs to be modified, a chainsaw file works best for that, and/or you can polish it with flitz on a felt buffing wheel of a dremel tool

I'll add that I've never had ar ar that was very accurate with green tips--- I'd use those for spray n pray or plinking bit not an accuracy round for sure...and they usually cost more than they should

 

[rpol98]

can you find out what mags the previous owner used?

it looks like the middle "fin" of the barrel extension feed ramp is causing those gouges, judging from the 2nd pic. I usually smooth that out, knock off some of the sharpness, and polish, before I install the barrel in the receiver on my builds to avert exactly that kind of symptom. But the bullet tip should be riding up the trough to the left or right of that fin, not hitting the divider fin dead-on.

is the barrel clocked nicely? i.e. the barrel extension M4 feed ramps lining up with the receiver M4 feed ramps? or are the off a smidgeon?

I've found PMAGS in AR-15's with plain-Jane Green Tip to be ho-hum ultra reliable. 25% feed failures is unusual.

 

[wvbearhunter]

Run a bore brush around the chamber and polish the feedramps

 

[wvbearhunter]

Sometimes small sliver of brass and can wedged in there

 

[eod.mickelson]

I heard back from him earlier today, he used 20 round lancer and ARstoner mags.

It does appear clocked appropriately, especially as compared to my other ARs. I did lightly emory cloth the feed ramp a bit and there are no burrs on it that I can feel.

If using the same type of mag that he did doesn't fix it, Ill probably send it back to Seekins to have them take a look.

 

[rpol98]

I heard back from him earlier today, he used 20 round lancer and ARstoner mags.

...

well, both of those are metal feed-lip mags. could be the critical factor there for this upper.

 

[cohunt]

well, both of those are metal feed-lip mags. could be the critical factor there for this upper.

And metal feed-lip mags can be tweaked to present bullet tip up to improve feeding

 

[ARlife4me]

I don't have a Seekins rifle or upper, but do use pmags and other poly mags with 62lap ammo. Never any issues feeding or extracting thus far. I do have some lancer, but use them for 300bo only.

Does it eject at the correct position (clock wise).