My son and I just built our first rifle.  Took about 30 minutes thanks to the info available in this website.  We used a BCM barrel assembly and a yankee hill lower with a DPMS trigger parts, and a magpul adjustable stock.  Everything looks great except there is "play" between the upper and lower receiver.  How much play is acceptable?  Can there be too much play, etc.  

Haven't shot the rifle yet because of the "play".  Yankee Hill has a plastic part to remove the "play" between upper and lower parts.  Is the part necessary?

Any help would be greatly appreciated.

A lot of guys will say not to worry about it. I personally cannot stand a lot if play. I have found a #7 print on the front take down lug removed all the play. But you will need to replace it almost everytime you take it apart.

I installed a accuwedge in one rifle yesterday and it serves it's purpose. There is still a wee bit of play in the front, but nothing like it was.

IT IS NORMAL. Doesn't affect accuracy or function. I don't like it either but it is normal.

BCM uppers seem to be on the "loose" end of the spectrum, probably because they want to make sure they'll fit everyone else's lower.  I don't think it's possible to have "too much" play, and frankly from my experience it's more common for a rifle to be on the loose side (I've owned Bushy, LMT, Colt, and a BCM/LMT combo).

Don't waste money/time on gimmicky rubber junk, just shoot the dang thing.

Or you could do what I do...

Keep always 2 or 3 lowers from different manufactures and when building a new rifle I try them  all and finally assemble with the tightest fitting one...I have had good luck with Stag, Essential Arms and Spikes...My BCM upper sits tightly on one of my Spikes and the Essential lowers were also good...

How much "play" are we talking about?  A bit of a rattle?  A wiggle between upper and lower that you can feel?  Some visible overlap on either side when you try to move the lower side-to-side while it's installed on the upper?  Or are we talking about something you can measure with a ruler instead of a feeler gauge?  The plastic part you mention is called an "Accuwedge," and it provides some support for the takedown lug on the upper when it's engaged in the lower.  It won't have any real effect on side-to-side play, just vertical.

I would not be thrilled with a new upper and a new lower not being a firm fit with each other, but my maximum play standards are really in the "feeler gauge" range; if you have more than that then you have a problem.  And you need to take some measurements-use a good dial caliper and find out exactly how wide both the pivot and takedown lugs on the upper are (measure three times with a short pause between each measurement), then find out exactly how wide the space between the pivot lugs is, and how wide the space in the rear of the lower for the takedown lug is.  Finally, make sure your pivot and takedown pins are the correct diameter; they should be 0.250" with a pretty close tolerance.  For a reference, you could look at the blueprints posted on the ARFCOM Information Library page.

I have a little play between my receivers, which used to bother me until I learned that military M16's have play between the upper and lower receivers. This made me feel a lot better, so now it will be left as is. Also, I've heard that installing an Accuwedge will make pushing in the take down pin a lot more difficult.

stick a foam ear plug in the back of the lower and call it a day.

This

Great looking rifle

I went to gun show today and picked up several rifles, RRA, colt, S&W and they didnt have any "play" between the receivers.  I thought we we getting better parts.  Tomorrow after work, I break the rifle down and measure the pins as wa suggested.  I think I have a 0" to 1" micrometer.  

Would getting pins from BCM, upper receiver manufacturer, or yankee hill, lower receiver manufacturer,take some of the play out of the rifle?

Perhaps you should shoot it first and see if it isn't up to your standards.  It shouldn't affact accuracy, but who knows?   If you don't shoot it, how will you know if the wiggle is bad?  Or is it embarrassing when you show it to people?

Jay

Some "play" is normal, and aids in disassembly. You also bought parts from different manufacturers and expected NOT to have some sort of tolerance differences? A rifle with zero "play" will develop some with use. If you want a rifle with no looseness I suggest a bolt action, as some clearances are need on most semi-autos in order to maintain reliability.

 

#7 print?

I'm concerned about the receivers coming apart at an inopertune moment and causing an issue, like taking a chunk out a cheek or an eye.  Besides this rifle is going to Ft Bragg as a practice weapon for my son.  The army isnt giving these kids enough rifle practice, so we are building him one topractice with at a private range before he deploys.  I want my kid to shoot real well when he deploys.

I'll get this rifle straighten out, He will use it a lot, and the army willl put hiim on a SAW.  I guess he'll have to aim and fire any way even with the SAW.

The pins are retained by springs and plungers if you assembled it correctly. DPMS lower parts are also some times out of spec. Cheaper is seldom better. It seems that people who are new to the AR platform just can't understand some play is normal. All of the rifles he shoots in the military will have some play. I have an old Eagle arms pre-ban rifle with a stainless barrel and free float hand guard. It has a lot of play but shoots 1/2 moa all the time. A good barrel and trigger along with good sights or optics are the key to an accurate AR. The reason there is some play is the same reason you can swap uppers and lowers around. This subject has been worn out. Do a search, you see it over and over.

+1

does this play create rattle?

Not going to happen.  Not possible.  The rifle is fine.  It's held together by 2 captured pins, it's not going to "fly apart".  Doesn't matter if it "rattles" either, whatever that means.  Trust us, you're GTG.

I would bet that any rifle your son touches in the service will be MUCH looser than the rifle you just built. It sounds like you don't want to listen to us that your parts are fine, but that is the truth!