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View Full Version : upper to lower fitment issue


sickboy774
07-09-2009, 12:17 PM
OK so I get my DPMS 16" A3 upper from MidwayUSA yesterday and when i tried to attach it to my LRB lower the rear pin would only go in with "a little encouragement." I tried the upper on my sundevil lower and it goes on without issues and there is a little bit of space between the two. I have not fired the upper with the LRB lower yet but there is little to no gap between the upper and the lower. everything seems to function correctly. I dont have dummy rounds to test ejection. before it get the posting...should i add pictures? hehe. thanks.

Eroland7
07-09-2009, 12:23 PM
IF you have function tested it, then i wouldnt worry about it. All uppers and lowers fit together slightly differently... I wouldnt stress over it.

Agustav
07-09-2009, 12:34 PM
They all do that when new... It will loosen up after a few times!

Eroland7
07-09-2009, 12:50 PM
They all do that when new... It will loosen up after a few times!


+1 put a few hundred rounds through it, then i bet the pin goes in and out smoothly...

MasterYong
07-09-2009, 2:48 PM
Yeah I have a few uppers that don't mate quite right to the lowers in terms of the pins. They get a little stuck- in fact two of my uppers require a very gentle reminder from a rubber mallet to get the pins to seat properly. They're getting looser- I figure another 10 range trips or so and the pins will move smoothly, if not it's dremel time.

cfm117
07-09-2009, 2:53 PM
On mine the stock buffer tube went like half a thread to far forward into the lower causing about a 1/16 in gap. I had to file down the tube a tad to make it sit flush.

Flying Bones
07-09-2009, 3:02 PM
How about the slop between the upper and lower...it's not much but it bugs me. Whiskey Tango Foxtrot is up with that?

MasterYong
07-09-2009, 3:05 PM
Get an "accuwedge". They rock. You can use o rings too but the accuwedge is pretty inexpensive. Just add it to your next online black rifle parts purchase.

http://www.adxtactical.com/store/pc/viewPrd.asp?idproduct=249&idcategory=0

http://www.riflegear.com/p-456-dpms-accu-wedge-ar15.aspx

I bought three the last time I ordered from riflegear even though I only needed one. I had too much play between my Sabre Defense upper and my Desert Ordnance lower so I used one and now it's tight as all hell- it's almost outright difficult to get the rear pin in now, it takes a lot of pressure, but it took care of the wobble straight away.

tiger222
07-09-2009, 3:06 PM
if the rear pin is a tight fit, you can get a drill and open up the hole slightly.
alot of lowers and uppers are not "exact" and may require fitting.

Once A Marine
07-09-2009, 3:08 PM
How about the slop between the upper and lower...it's not much but it bugs me. Whiskey Tango Foxtrot is up with that?

That was done by design, actually. Since all of the AR's action is contained in a straight line through the upper receiver and buffer tube, the fitment between upper and lower doesn't have to be precise, which allows for the quick, modular swap between various upper/barrel combinations and a single lower.

BigBamBoo
07-09-2009, 3:14 PM
.............

MasterYong
07-09-2009, 3:30 PM
Forget a accu-wedge...bed the front lug of the UPPER...this will take out the "slop" and is more sanitary then the accu-wedge.

If you need help on this...let me know and I will try and put some pics and "how to" together and post it.
You can also find this info online too.

Take care,Stan

Out of curiosity, what exactly isn't "sanitary" about an accuwedge? Seems like an odd choice of words...

I like the accuwedge because I can swap uppers all day long and if one config doesn't need it I can easily remove it. I don't see the point in bedding if it's a job you may have to redo in the future.

Just curious.

BigBamBoo
07-09-2009, 3:46 PM
............

sickboy774
07-09-2009, 4:38 PM
sweet. thanks for the replies. BTW. I saved 50 bucks on the upper because i registered on midways site. they sent me an email a week or so before my birthday and was given a discount on everything. talk about a great company!

MasterYong
07-10-2009, 7:56 AM
Well if you open your rifle....the accu-wedge may fall out....it looks cheesy...and it is putting pressure in the wrong area (pushing up against the bottom of the rear upper lug).

If you are going to use a accu-wedge...save yourself a few bucks and go to the hardware store and buy a 5 cent O-ring and put it on the front lug. Or use a disposable soft ear plug as you would a accu-wedge.

But I myself don't like cheesy things on my $2000+ dollar AR so I choose to bed the front lug. I don't swap uppers so this is not a issue. The bedding can be removed in a matter a min.'s and you can not see it. It won't fall out if opened.

Just my way of doing things...again....I don't like jack-leg ways of doing things.

Peace,Stan

OK... now define "cheesy".

have you ever seen one in person? Held one? Seems like they're made out of pretty high quality rubber to me. Also, at least in my lower, the fit is very tight to the outer walls of the lower. There is no way that thing could ever possibly fall out.

You wanna talk "cheesy"? What's this advice about using o-rings and disposable ear plugs? THAT'S cheesy. And I'd love to see your source that shows that the accuwedge is "putting pressure in the wrong area"....

LOL if you think that a little pressure is going to hurt your $2000+ AR then maybe you should have built a different AR. The ones I've had experience with seem to hold up to a lot more than a little pressure! :p

Barney Gumble
07-10-2009, 9:14 AM
That was done by design, actually. Since all of the AR's action is contained in a straight line through the upper receiver and buffer tube, the fitment between upper and lower doesn't have to be precise, which allows for the quick, modular swap between various upper/barrel combinations and a single lower.

+1

This is the only post here with any useful information.

If you are OCD about upper/lower fit then by all means have at it, but just be aware that it has no bearing on function or accuracy.

MasterYong
07-10-2009, 9:19 AM
+1

This is the only post here with any useful information.

If you are OCD about upper/lower fit then by all means have at it, but just be aware that it has no bearing on function or accuracy.

I never said it did. It just drives me nuts to have a gun that has so much play that it feels like it's going to rattle apart!:eek:

akjunkie
07-10-2009, 9:44 AM
my 2cents..

the Accuwedge can also be slightly Trimmed with a razor blade if it is "Too tight."

popeye4
07-10-2009, 9:52 AM
That was done by design, actually. Since all of the AR's action is contained in a straight line through the upper receiver and buffer tube, the fitment between upper and lower doesn't have to be precise, which allows for the quick, modular swap between various upper/barrel combinations and a single lower.

Per Zediker's book on the AR15, it can't be too loose, but it can be too tight. The lower is just a case for the fire control group......

Tony.
07-10-2009, 9:57 AM
I never said it did. It just drives me nuts to have a gun that has so much play that it feels like it's going to rattle apart!:eek:


It won't, that is what detents and springs are for. Get over it, that is the way it was designed.

BigBamBoo
07-10-2009, 10:13 AM
...........

Tony.
07-10-2009, 10:37 AM
Glad your laughing....because you obviously do not know what your talking about. And...again...from your replies you strike me as a guy who does things halfassed.
Have I ever seen a accu-wedge?? LOL...see pics...yeah...in fact....give me your address and I will give you one or two since you think they are the best thing since sliced bread.

You come across as one of those people who just because you own it...it is the best and no one can do better. Let me guess...you use 10/30 mags and bolt on all those tactical widgets cause your a wanna-be tacticool mall ninja type. Heck...bet you run around the house making machine gun noises with your AR...and I bet your thinking (if your self aware enough to self analyze) how does he know I do that!?!?....now thats funny!

Peace,Stan

:rofl2::rofl2::rofl2::rofl2:

popeye4
07-10-2009, 10:41 AM
Glad your laughing....because you obviously do not know what your talking about. And...again...from your replies you strike me as a guy who does things halfassed.
Have I ever seen a accu-wedge?? LOL...see pics...yeah...in fact....give me your address and I will give you one or two since you think they are the best thing since sliced bread.

You come across as one of those people who just because you own it...it is the best and no one can do better. Let me guess...you use 10/30 mags and bolt on all those tactical widgets cause your a wanna-be tacticool mall ninja type. Heck...bet you run around the house making machine gun noises with your AR...and I bet your thinking (if your self aware enough to self analyze) how does he know I do that!?!?....now thats funny!

Peace,Stan



Lighten up. Accu-wedge is the standard (USAMU uses them). If you want to do something different, have at it. But Accu-wedge is still the standard and it works just fine.

brokestudent12
07-10-2009, 10:47 AM
Come buy the Denny Billet Lower I have for sale, no accuwedge needed, it's built in :D

BigBamBoo
07-10-2009, 10:48 AM
............

yakmon
07-10-2009, 11:23 AM
Bigbambo if you want to give away an accuwedge I'll send you a SASE.

BigBamBoo
07-10-2009, 11:43 AM
...........

mik3
07-10-2009, 3:09 PM
I personally don't like extra crap in my AR. That's just one extra part to deal with. I don't mind the slight gap between my upper and lower. I can easily crack mine in half to run water or whatever I have nearby to clean it up. KISS...
Nice AR Stan, I'm in the process of building something similar to yours.

BigBamBoo
07-10-2009, 4:16 PM
..........

JohnBrian
07-10-2009, 4:34 PM
Yeah I have a few uppers that don't mate quite right to the lowers in terms of the pins. They get a little stuck- in fact two of my uppers require a very gentle reminder from a rubber mallet to get the pins to seat properly. They're getting looser- I figure another 10 range trips or so and the pins will move smoothly, if not it's dremel time.
I have one AR (a RAW) and one upper. However, I have to beat the rear pin in as well. I have to use a brass punch & hammer to get it out. Not a big issue as the only time I take it apart is to clean it but it would be nice to be able to push the pin out with a bullet or cleaning rod.

So what do I do to fix this? Drill/ream the pin hole in the upper I am assuming?

aplinker
07-10-2009, 4:41 PM
Lighten up. Accu-wedge is the standard (USAMU uses them). If you want to do something different, have at it. But Accu-wedge is still the standard and it works just fine.

I don't like pieces of rubber in my rifle. Too many ways they can get chewed up and cause issues.

The rattle is like the sproing - it's just a part of the rifle.

NRAhighpowershooter
07-10-2009, 4:50 PM
...bet you run around the house making machine gun noises with your AR...

what's wrong with that?? I do it all the time in my jammies and a GI steel pot! :p

popeye4
07-10-2009, 9:24 PM
I don't like pieces of rubber in my rifle. Too many ways they can get chewed up and cause issues.

The rattle is like the sproing - it's just a part of the rifle.

I don't use one, either. My rifle isn't snug, but it doesn't rattle, either.

The "sproing" is much less noticeable with earplugs instead of muffs..... ;)

ukdkbr
07-10-2009, 9:58 PM
OK so I get my DPMS 16" A3 upper from MidwayUSA yesterday and when i tried to attach it to my LRB lower the rear pin would only go in with "a little encouragement." I tried the upper on my sundevil lower and it goes on without issues and there is a little bit of space between the two. I have not fired the upper with the LRB lower yet but there is little to no gap between the upper and the lower. everything seems to function correctly. I dont have dummy rounds to test ejection. before it get the posting...should i add pictures? hehe. thanks.

Me and my dad each build an AR with LRB lowers and EVERYTHING is tight, I had to do some serious man-handling with the RRA grip to get it on. It's a pain to put it together but I like the fact that everything fit super tight! It fit tight on my Stag upper where my mega lower was pretty easy, but not loose.

God Bless The Mauser
07-10-2009, 10:20 PM
I just cut a piece of aluminum out and put jb weld on the top and put that in between the upper and lower in front of the rear takedown pin. I put some oil on the receiver so the jb weld wouldnt stick. It's not elaborate but I did what I could with what I had.

J-cat
07-10-2009, 10:42 PM
How about the slop between the upper and lower...it's not much but it bugs me. Whiskey Tango Foxtrot is up with that?


You can bed the upper to the lower.

popeye4
07-11-2009, 11:19 AM
You can bed the upper to the lower.

You can, but you probably shouldn't. The lower isn't a gunstock, it is a case for the trigger group and a holder for the magazine. Having a little freedom of movement between the upper and lower removes any possible stresses between the two pieces. Other than a good trigger, all the accuracy enhancements are to be obtained in the upper (bolt carrier fit to upper, bolt fit to barrel extension, excellent barrel, sights, etc). A tight lower to upper fit can add stresses to the upper that don't help with accuracy.

We sometimes assume that precision mechanical devices need to be absolutely tight and vibration free. That isn't the case here. The Accu-wedge clearly offends some aesthetic sensibilities, but it is squishy and will snug up the fit (for those who want that) without really adding any unneeded stress between upper and lower.

But do what you want, it is your rifle and your money. If you want an absolute rock solid mechanical connection between upper and lower, then knock yourself out. But don't delude yourself into believing it will make your rifle shoot better.