Trouble with a stripped lower....

[HKFan9]

So I have built a bunch of AR's using various stripped lowers from different roll marks and different manufactures with no problems what so ever.

My buddy wanted me to build him up a rifle so we shopped parts, i told him pick a lower he wanted.. get it sent to my FFL, I will build the lower while you decide what you want to do with the upper.

He ordered a Aeropercision lower. I was always a firm believer in a lower is a lower is a lower... however I will admit I sub-consciously and consciously usually stick with the CMT receiver family. (Stag, Colt, Noveske ect.) Never any issues and CMT/Stag imho are a great company.

His lower came, I looked it over, everything seemed ok so I started assembly. Everything went great, except that I noticed the mag release was sticking pretty bad. It is semi-normal for people to complain of a sticky mag release when first assembling a lower, but the last one I built myself cured itself with in a minute. His however started to get worse.

I took it back off to discover there was grinding and chipping on the inside edge of the inside edge of the mag-well where the magazine catch slides back and worth. It seems that it is either that that edge was some what out of spec and catching on the mag release.... nothing a little file and stone wouldn't fix... or it seemed that it was out of spec and allowing the mag catch to shift or cant ever so slightly where it was grinding itself against the lower.

I think it is easily fixable (it also could be the parts from the DPMS parts kit he gave me may be out of spec).

Before I took action.. I was just wondering if anyone else had this issue or something similar... or any helpful suggestions.

 

[madcratebuilder]

I think it is easily fixable (it also could be the parts from the DPMS parts kit he gave me may be out of spec).

I would try another mag release before I started work on the lower. The mag release should be smooth as butter. Double check you are using the correct spring. I've assembled over a half dozen AP lowers and all have been gtg.

 

[NickySantoro]

Interesting thread. I had a problem with a poorly machined cast DPMS lower on one build and an out of spec DPMS hammer on another build.

 

[mikems]

I have heard of this kind of stuff happening a lot when DPMS is matched up with receivers/parts from other companies. DPMS is a good company, but if it was me I would not interchange DPMS parts on other rifles, and vise-versa. Hope it all works out for you guys!

 

[Technosavant]

I've used DPMS parts with an AP lower; no issues at all. Sounds like something is indeed amiss- could well be a lower with a problem or it could just be the mag catch.

 

[HKFan9]

He is waiting on a few parts to finish the lower, mainly the buffer tube and castle nut so I am going to bring one of my complete lowers and see how my mag release works in his lower. Hopefully from there we can determine what the cause of it really is.

I am really hoping it is not the lower, a mag release is cheap to replace... thinking about it as I type this I might even have a spare one laying around here somewhere.

 

[HKFan9]

I will also say I am not very impressed with the DPMS parts kit.

This is my first time using one, and I am not trying to bash... but the trigger was even sticking instead of resetting and having the disconnect catch it, It took it awhile to not catch and hang up.

 

[Technosavant]

This is my first time using one, and I am not trying to bash... but the trigger was even sticking instead of resetting and having the disconnect catch it, It took it awhile to not catch and hang up.

That can happen with anything; I had a Daniel Defense LPK where the fire control group was not going to play nice. The trigger would allow the hammer to drop when released (so it would essentially have a release trigger). DD swapped out the parts without a problem though.

Some mixing and matching showed it was an issue with THAT trigger mating to THAT hammer... still, if it's going to be like that I have a hard time trusting it.

 

[HKFan9]

Yea I don't blame you. Luckily his trigger was just sticking when trying to "fire" from reset... it wouldn't reset at first with out a little nudge, but it worked itself out. Brand new parts... no lube yet... guess it is to be expected. I haven't gotten a chance to try a new mag release in his lower yet to see what the issue is.

 

[Skavatar]

if i remember correctly, Aero makes lowers for several AR companies, Surplus Ammo & Arms (i built one, no problems), Spikes, and i think PSA used them early on.

just like any other product from any other company, they'll occasionally have a few imperfect items.