AR question

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carprivershooter

New member
I want to put together and AR for general use long range shooting, home defense, zombie protection, and varment plinking. I know the parts I need and have ordered several uppers and lowers but when i fitted them together there was a fair sized gap[ between the upper and lower. I used a feeler gage to measured the gap on two rifles a gap was .0004s and the third the gap was .0005. So the question is what is your thoughts on the gap range between the upper and lower?. I think the smaller the gap the less stress on the rifle when shooting. The parts used were a Stag upper, BCM lower,CDNN,Bravo.
 
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mc223

New member
So you numbers are 4 and 5 ten thousandths. That is like a tenth of a human hair.


If it bothers you get an Accuwedge. And I have never had an Accuwedge turn into gummy goo.

Quite frankly with those numbers the pins would be difficult to insert.


The loosenees is not an issue as the parts that matter are in the upper.
 
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Mobuck

Moderator
Actually the gap makes little difference except cosmetically. Even with some wiggle, the rifle will shoot fine. Are you talking about upper/lower from the same maker or mix&match? Occassionally, I'll run into a noncompatable upper/lower which is too tight to pin but I don't worry about some gap. If there's wiggle, you can use the little rubber thingy to tighten it up some.
 
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carprivershooter

New member
error

I meant 3/1000 and 5/1000. I don't think wiggle is a good thing. I think 2/1000s would be exceptable and these are mix match parts.
 
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bigghoss

New member
at work I used to carry an m16a1 that was so loose you could easily get a dime between the receivers and it was still an accurate rifle and never malfunctioned on me, though I never really got the chance to run it REALLY hard. two years ago I finally got it swapped for a less loose A2 but you can still see through the receiver. this is typical of all the rifles where I work and I've never seen it affect accuracy or reliability. it would be much more annoying on a new gun though vs. an old beat up one.
 
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Volucris

New member
It's meant to be that way so it's easy to field clean. It does not affect accuracy at all. Accuwedges just turn into gummy goo after shooting.
 
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Ridge_Runner_5

New member
As long as the receivers snap together and the hammer can keep hitting the firing pin, the gap is irrelevant. I had quite a wobble in mine. I got so anal retentive about it, that I bought a custom matched receiver set from Wilson Combat, which are quite snug with each other.

Weapon reliability or accuracy wasn't affected, but I liked the solid feel.
 
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HiBC

New member
I think if you get your micometer out you will find nearly all hinge/takedown pins are right at .245 and the holes will plug gage no less than .250.
The ideas behind geometric dimensioning and tolerancing would take a long time to explain,but rest assured,it is as it was intended to be.It most cetainly does not suggest a quality problem.
If it really bothers you,what i did,after measuring all the pins at a few gunshows,and accepting they are all exactly .005 undersize,is plug gage the upper/lower assy to determine what pin size would just fit.Then I took some mold core pins to a fine old Monarch 10 in EE toolroom lathe and made pins that fit.I did it because I could.Probably does not matter.
 
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madcratebuilder

New member
HiBC said:
I think if you get your micometer out you will find nearly all hinge/takedown pins are right at .245 and the holes will plug gage no less than .250.
The ideas behind geometric dimensioning and tolerancing would take a long time to explain,but rest assured,it is as it was intended to be.It most cetainly does not suggest a quality problem.
If it really bothers you,what i did,after measuring all the pins at a few gunshows,and accepting they are all exactly .005 undersize,is plug gage the upper/lower assy to determine what pin size would just fit.Then I took some mold core pins to a fine old Monarch 10 in EE toolroom lathe and made pins that fit.I did it because I could.Probably does not matter.
Click to expand...

Exactly right!

The 'slop' is normal, it does not effect accuracy. It can 'bug' many shooters, me included.

Mega makes a lower with a lower tensioning screw. These can be added to any AR lower.

http://www.rainierarms.com/?page=shop/detail&product_id=121

You can use a accu-wedge or a piece of foam ear plug. A strip of electrical tape on the top rail of the lower at the take down pin area works very well, use a one to two inch strip and trim to the width of the rail.
 
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tirod

Moderator
" general use long range shooting, home defense, zombie protection, and varment plinking. I know the parts I need and have ordered several uppers and lowers" (snip)

Gap? Means nothing. My service rifles rattled after a few years use, still shot expert.

More importantly are the effective ranges - long distance precision vs. HD/zombie. Those are really two completely different jobs, different targets, different calibers if you go that far. One lower will do for both, without being a major compromise. The uppers will be completely different.

For example, a target upper could be a Les Baer .264LBC, 20"+, freefloat, with bipod, A3 upper and minimum 3x9 target scope. The "short" range gun, a 16" 6.8SPC with reddot and rifle handguards. Don't forget to mark the mags distinctively. Either would be far more effective than 5.56 - and are 100% legal to hunt in the US.

What did you get?
 
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carprivershooter

New member
i decided

to sell off my parts to a friend for what i had in them and went to my local gun shop and picked up as rock river tacital entry. He was glad i made up my mind. He is a good guy letting me fit and handle the parts. The Rock River is tight, well made and a tack driver with opensights. Looking for a mid priced scope. will be shooting coyotes, bobcats, i am also thinking about a night scope with IR. for the varments. The RR does have a gap between the upper and lower it measures 2/1000ths. I just think close tolerances make a better weapon, I guess it's my issue. thanks to all who provide input to my question.

My issue colt M-16 that i carried in viet nam was always a problem. I stop carring it and carried a 12 gauge and and vintage grease gun 45 apc. after a little practice i could fight 2 and 3 round burst and be effective.

I have read good reviews on Rock River, the other bands I read about just didn't impress me. I am happy with my weapon. And Colt I have not been able to get over my distrust. When my life depended on the M16 to work it wasn't always going to fire or eject as it needed to. ANd yes it was looked over my the armorer more then once who could not find the prorlem, and I loaded my mags with 19 rounds like recommended. at the time that was an issue for certan models of the weapon. I also understand that Colt is the standard by which other AR and M 16 measured.
 
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wwd88888

New member
No worries

Everything that impacts accuracy on an AR is in the upper receiver is is aligned with itself. I guess the stock being slightly out of alignment could impact accuracy, but not to the level you would ever notice.

I've never seen an AR that did not wiggle.
 
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tirod

Moderator
The stock being out of alignment wouldn't make a difference on almost any weapon - how you hold it has nothing to do with the sights on the barrel and upper pointing at the target's potential impact.

A few thousandths, or a 1/8" rattle, no effect on the AR Stoner design. None. Compare that with the M2 .50 cal - the barrel is screwed into a carrier that cycles the action in the chassis. It's not fixed at all, and yet has great accuracy out past 1000m any day of the week. It's still used as a long distance sniper weapon when it can be.

A few thousandths play is the province of new shooters raised on low quality bolt guns and a misunderstanding of rifle dynamics. What controls accuracy more often relates to barrel quality, consistently loaded high precision ammo, and shooter skill. A lot of shooter skill.
 
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Volucris

New member
So let me get this straight...


you bought all the parts you picked out to make your ideal AR-15 and then....just because the rifle had the tolerances between the upper and lower IT WAS SUPPOSED TO, you sold it all and got an overpriced RRA gun with a novelty carrying handle on it?


That was quite the derp thing to do.
 
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Quentin2

New member
My Daniel Defense upper on a S&W lower has about 1/32" gap (just eyeing it, never occurred to me to measure). And my ArmaLite upper that I moved over to an ArmaLite lower has about half of that, again just eyeing it. Even so the DD outshoots the tighter ArmaLite so I don't mind seeing a little daylight where the wiggle is.

Hey carprivershooter, the Colts of today are a lot better than the ones we had in Nam! Actually the one I had then worked fine but anyway, bet you'd love a Colt today.
 
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carprivershooter

New member
YEP

Volucris Yes I did. you see i see thing one way.... my way. and My rockriver didn't come with the unnecessary carry handle. But did come with and awesome set of iron sites. THe rock river is no more a novelity then any other AR/AK rifle. It's what you decide to spend your money on. I paid cash from my gun money that I save. I have a fine rifle that will serve me well and I am Happy With My Decison.
 
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tirod

Moderator
Easy, guys. Nothing illegal or immoral in spending your money any way you want, right? Shoot that Rock River and enjoy it. That will be the whole point.

As for the clamp on carry handle, lots of us get a used one and cut it down. Best rear BUIS on the market for the price, mine came from Ft. Hood for $32 shipped.

It's all how you get your money's worth.
 
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