AR Upper/Lower Fit

[aclark]

I just received my DD upper from Smartgunner.com yesterday and as soon as I pulled it out of the box I HAD to get in on my DM lower ASAP. I lined up the front hole for the pivot pin and slid the pin in. Then I swung the back half of the upper down, but the fit was too tight for it to lock in place. I got it jammed trying to push it in, so I tapped out the front pint with a punch and got ready to try again.

This time I lined up both holes at once. It seemed to fit, but I could tell it was forward a tad. I put some pressure on the front of the upper and slid the read pin in with just my fingers. However, the front pin I had to tap in with a rubber mallet.

I function tested everything, and it seems to run fine. My question is will I see any problems when firing the gun from such a tight fit? Will it just make it a pain when I go to clean it always needing a punch set and a mallet? And, Will the fit loosen up after some time?

This is my first AR, and I'm pretty sure everything is correct on it. I built the lower myself with a DM lower and RRA LPK, so there may be something outta whack there, but I don't really see anything.

 

[Lock n Load]

Although not an ideal fit, especially from DD (you may send them an email and see what their response is). I have had a few upper/ lowers fit real tight where the pins had to be lightly tapped in.

Unless it throws it in a bind or twist it shouldnt effect function or accuracy. The only true tell is to test fire and see.

Doesnt sound like anything is in error w/ lower & LPK, sounds more like the hole spread is longer on either the upper or lower since you stated it was forward a tad..... and yes its a pain to clean these when you have to hammer out the pins.

 

[Gamez235]

DM? I am guessing Delaware Machine? If so I'd say it's the lower, I had more trouble fitting them into uppers than most other lowers. They always were tight in the back.

 

[melensdad]

My question is will I see any problems when firing the gun from such a tight fit? Will it just make it a pain when I go to clean it always needing a punch set and a mallet? And, Will the fit loosen up after some time?

Believe it or not, this is not as uncommon as you might think. Brand X and Brand Y should fit but don't always have a perfect fit. There are tolerances that each company has, and if one brand's part is within "spec" but on the outside edge of that spec and another brand's part is also within "spec" but on the opposite edge of the spec then you get a hard to fit gun. That is likely what you have.

Will it affect accuracy? NOPE.

Will it affect function? NOPE.

 

[aclark]

I was just concerned because most the videos I have seen of people field stripping their rifles, they just pop the rear pin and the upper swings out fairly easy. This does not seem to be the case for me.

 

[loony1]

DM? I am guessing Delaware Machine? If so I'd say it's the lower, I had more trouble fitting them into uppers than most other lowers. They always were tight in the back.

This

 

[bstewrat3]

I had this same problem with a couple Roggio Arsenal lowers. I sent them back and they made them right. It was a QC problem not a matter of their inhouse specs. The buffer tube threads were too tight also.

 

[aclark]

Problem is that Delaware Machine went under a while back, and while there are still a few floating around, I doubt I could get a new one. Guess I may be saving for a new lower.

 

[aclark]

Oh and for the record, here's a pic (iPhone). I'll do a more detailed post at a later time.

 

[mvician]

The pin will loosen up over time. Don't grind on anything.
Nice looking rifle.

 

[aclark]

Well I "slammed" it shut on the pivot pin a couple of times, and it looks like everything is lining up correctly, its just that the "nub" on the upper is a little wide, or the rear of the channel on the lower is a bit narrow. Either way I can see both sides wearing off a bit to make the fit. It will take a few times of taking it apart and putting it back together to get it to move totally freely, but in time it shouldn't be a problem.

 

[Colt556]

I wouldn't worry about it to much. If it fits and everything works right it should be fine. I'd rather have one a bit tight that to loose. It will loosen up with use as well. Also is it dry? Might try just a drop of LCP on the pins.

 

[jd4320t]

The pin will loosen up over time. Don't grind on anything.
Nice looking rifle.

This.

My Stag upper was really tight on my Stag lower when I first put it on. Now it is fine.

 

[malern28us]

I can tell you after having the same thing with my Delaware lower... Just shoot the thing!! After a couple hundred rounds my fit is perfect to me. I will NEVER have to worry about any pins falling out. It even makes a nice "snick" sound when I put it together now.

 

[aclark]

Thanks for all the replies guys. After working it a few dozen times its starting to loosen up. I still need to "slam" it shut, but i can pop the rear pin in and out with my fingers now, and it will pivot on the front pin. You can smell the steel rubbing together when I slam it which is kinda weird, but I'm not worried about it anymore. I just wanted to make sure something wasn't out of spec that needed to be taken care of ASAP.

Now I just need to shoot it. Its driving me NUTS. I really don't want to go to JP or Winamac right now, and I can't shoot it indoors at Blythe's, so I guess I'm just gonna have to wait.

 

[Johnny C]

Roggio Arsenal lower

I got one back after Obammer fever hit, because it was all I could find at the time. My problem with it was that the top wasnt flat, it humped up a little in the middle. I had it for over a year before I finished it and tried to mate it to an upper. The upper was an LMT CQB, so I trusted the upper specs, and removed a little bit of material on the lower to get it to mate up. I am a stickler, so I am looking at replacing the lower with an actual LMT one, and getting rid of the Roggio Arsenal lower.

Johnny C