How to tighten up upper lower fit?

[Firemarshall27]

I have a POF lower and a Viltor and Larue upper and the fit on both uppers have a good bit of wobble in them even with an accu wedge it still has some play. Is there anyway to get a better fit? I dont even know if it affects accuracy or not it just bothers me.

Thanks, FM

 

[STI_1911_Guy]

Re: How to tighten up upper lower fit?

The tests that i have ran with various ar's have shown little to no increase in accuracy(none got worse). Now none of them have been super sloppy to begin with but really for me all tightening the fit did was set my mind at peace. I never really cared for the accu wedge. I have had good luck with the JP tension pin. But some people dont like it because it requires an allen head to take apart and it takes time, yea more than pushing a pin but not much and it does make the fit as rock solid as possible. I have also heard of people "bedding the action" but mixed reviews on that. Also people have drilled and taped under the hand grip to place a set screw and push apart the receivers to make them tight. There are a few discussions about this already on hear i would search for them as well to hear some more. What kind of accuracy are you already getting?

 

[steelcomp]

Re: How to tighten up upper lower fit?

Armalite makes Match oversized pins for this reason. You can have a gunsmith do the conversion, but it;s a little of a PITA. The hard anno makes reaming the holes a bit of a task, and they need to be hand-fitted to really be "right", but in the end, you have zero movement. I agree that it;s more of a peace of mind thing, but if it distracts you from your shooting, even subconsciously, it can effect your accuracy. I just hate rattling rifles.

 

[BERTMAN77MK2]

Re: How to tighten up upper lower fit?

I purchase the lower receivers I want and lots of upper receivers
from wherever they are on sale--then just mix and match for that perfect fit!! (new upper receivers re-sell easily) I have noticed that most of my high dollar billet lowers are best off
with the same brand upper as have had some for quite a while before finding a perfect match---My particular POF lower mates perfectly with a YHM flat-top upper if that is of any help---and
my Larue and VLTOR uppers fit perfectly thus far on Rock River
and Colt lowers---have a GG&G upper mated to a Rock River lower
that is a perfect matched pair--look like they were machined as 1

 

[trident1982]

Re: How to tighten up upper lower fit?

Slop only effects the brain's accuracy, not the rifle's

Go to your near by hardware store...lowes, HD, Sears,etc., and buy a small asst. of black plumbing type rubber o-rings( you will want an asst. of sizes so that you can get the proper fitting as its all but impossible to gauge by eye and there is a million diff. size orings).....once you have the orings, find an appropriate sized one and wrap it around the front lug on your upper receiver...it can be tricky to get it to stay while you join the halves but just make sure you pin the halves together while the oring is properly wrapped around the front lug. Then just pin in the rear and this should remove damn near all your slop.

 

[Anchor Zero Six]

Re: How to tighten up upper lower fit?

Bedding the upper and lower is not too difficult and not as scary as it sounds.

In a nutshell you "fill" the gap between the upper and lower with bedding material. If you take time to tape and prep surfaces it will be flawless.

 

[teufelhunden]

Re: How to tighten up upper lower fit?

I have seen guys place foam ear plugs under the rear pin to tighten up an upper & lower. But this meathod was utilized because we were deployed overseas. USMC mentality "Do More With Less"

 

[JeffLebowski]

Re: How to tighten up upper lower fit?

Waste of time.

 

[BCP]

Re: How to tighten up upper lower fit?

I have seen people "bed" them with different kinds of tape (use your imagination). My CMMG+DPMS upper 308 setup was wobbly as hell so I used a JP tensioner pin to tighten them up. Finally, Armalite offers "national match" pins which are oversized to help with upper-lower lockup.

 

[jbailey]

Re: How to tighten up upper lower fit?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BCP</div><div class="ubbcode-body">I have seen people "bed" them with different kinds of tape (use your imagination).
</div></div>

That is what I do. I have one lower that is a bit wide in the front and it wobbles a hair with all of my uppers. A bit of black electric tape around the front take-down lug and it is tight as hell. Every once in a while (perhaps 2x per year) I take the old tape out and put in a new strip. Works great.

 

[shootist~]

Re: How to tighten up upper lower fit?

The Armalite National Match pins went in with no fitting for me and took the fit on that upper/lower from excess to about average. I used both the pivot and take down pins and put a spare pivot pin in the parts box for a spare.

 

[Turk]

Re: How to tighten up upper lower fit?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: trident1982</div><div class="ubbcode-body">Slop only effects the brain's accuracy, not the rifle's

Go to your near by hardware store...lowes, HD, Sears,etc., and buy a small asst. of black plumbing type rubber o-rings( you will want an asst. of sizes so that you can get the proper fitting as its all but impossible to gauge by eye and there is a million diff. size orings).....once you have the orings, find an appropriate sized one and wrap it around the front lug on your upper receiver...it can be tricky to get it to stay while you join the halves but just make sure you pin the halves together while the oring is properly wrapped around the front lug. Then just pin in the rear and this should remove damn near all your slop.

</div></div>
Pretty neat idea; will try it. Thanks.

 

[glock24]

Re: How to tighten up upper lower fit?

A couple solutions that I've seen;

JP Enterprises Tensioning Pin

Demon Tactical Quick Pin

 

[sobrbiker883]

Re: How to tighten up upper lower fit?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: firemarshall27</div><div class="ubbcode-body">I have a POF lower and a Viltor and Larue upper and the fit on both uppers have a good bit of wobble in them even with an accu wedge it still has some play. Is there anyway to get a better fit? I dont even know if it affects accuracy or not it just bothers me.

Thanks, FM </div></div>

I shim them with cut feeler guages. Pain to align when putting the receivers together but they work great. Cut them in a "D" shape rather than round so that the flat side goes up against mag well and lines the hole you drilled or punched up properly.

 

[Firemarshall27]

Re: How to tighten up upper lower fit?

Thanks for all the suggestions guys!