Has anyone ever thought of/tried this?

[Creeky73]

So, when I first started monkeying around with building an AR a few years ago, one of the things that drove me nuts was how loose the receiver halves tend to be when they aren't matched parts. Especially coming from a RRA, where the two halves were really tight together, I always felt like the sloppy fit from random halves gave the gun a sort of "defective" feel. Bear in mind this was from someone who had absolutely no experience to draw from on it (and still claim little, I am more of an "enthusiast" than a hardcore shooter).

I still dislike the feel, even though I understand that it matters little if the gun is functioning properly. My quest for a rattle-free gun is the only reason I bought a free-float hand guard, and I have the Magpul MOE rifle stock installed, so there is no rattle there. However, the only option I have found to tighten up the halves is the JP takedown pin, which I understand that a lot of people advise against because is makes the breakdown of your firearm a PITA in a pinch.

So has anyone ever considered this...I am no engineer so if this sounds impossible, so be it, but...

What if someone designed a rear take-down pin that had the expandable innards like the JP does, but operates on a quick-throw lever sort of like on most of American Defense's products? If you make the lever small enough, it is no worse than having an ambi safety installed...

Just a thought, and feel free to tell me I'm a moron. Thanks for your time.

[csmith]

Personally I think it's overkill, but they do have the Accuwedge for that (http://www.midwayusa.com/product/698479/dpms-accurizing-wedge-ar-15). The play between the two receivers isn't abnormal. There isn't a carbine I've touched that didn't have it. That doesn't encompass higher end ARs, most of my experience is with M4s.

[Creeky73]

I totally understand that it is something that a great deal of people will have no concern for, it is just a non-issue to them.

the reason I don't like the accuwedge is the same reason I don't care for the little tension screws coming on a lot of lower receivers these days: they push the halves apart instead of drawing them together.

I am just thinking that, if there was a way to eliminate that play without having to use a tool to break down the firearm, or otherwise significantly increase the difficulty or number of steps to break it down, its a win-win all around?

[csmith]

I'd have to guess the higher end ARs (Noveske, Larue, etc.) would be closer to what you're looking for, as my uninformed assumption is they have tigher specifications in their construction and therefore tighter receiver fit (the price can't all be in the name, right?) My second assumption is most every other manufacturer builds them in the fashion they do because they still function in spite of a loose(-er) fit between the receivers.

Basically, to get a better fit it comes down to a tighter specification during manufacture. Everything else is second hand.

[Koshinn]

My Noveske requires a tool to separate the upper and lower. I generally use the tip of a closed clicky pen since its soft plastic, but strong enough to get the job done and is the right size.

I've fired over 2k rounds through it and it has not loosened up at all.

[Hmac]

I have two rifles built on Noveske matched uppers/lowers and a Noveske Light Recce w/VIS. Those things lock up perfectly without even the slightest wiggle and I can get the pins out with just finger pressure. On the down side of that, neither of my two Noveske uppers nor the VIS will fit on any of the other Noveske lowers except the one it was matched to. Not really a complaint, just an observation.

[Creeky73]

I think the intention of my post may have been misinterpreted :)

I fully understand that the play doesn't take away from the function of the rifle, and I fully understand that tolerances will be somewhat different from one manufacturer to another. I also understand that when you are mixing and matching receiver halves, it will be next to impossible to get two halves to fit together nice and tight. It was not my intention to start a discussion as to why the slop is there, or why it should be ignored. I understand that it has zero impact on the operation of the rifle.

However, products like the accuwedge and the JP pin do exist, which tells me that I must not be the only person out there that finds the play annoying, and would like a solution that doesn't compromise the battle effectiveness of the weapon, in other words doesn't require a tool or add 3 more steps to the malfunction-clearing process. The complaints I have read about the JP pin always revolve around 2 things: they eventually shoot loose, and require a tool to break down the weapon.

On my rifle, I am running a JP pin, and I love how solid it makes everything feel. I have also had several people who handled it comment on how nice and tight everything feels as compared to others they have handled. My way around the whole "battle ready" issue of the pin is that I am running a Magpul MOE fixed stock, so swapping out the rear takedown pin is about a 2 minute process, and I keep all the parts and the allen wrench inside the buttstock, so it is always there.

I was really just trying to bounce an idea off you guys with the quick-release takedown pin. If you could get one that locked the receivers up tight without pushing them apart, required no tools to break down the firearm, left no loose parts inside the receiver, and never shot loose....I would be down for that part. I knew before I ever proposed this that the vast majority of members here will be far too practical for this, but I thought SOMEONE might think it was a decent idea, lol.

[jbjh]

It's not a bad idea, but there are some engineering challenges that will go along with it. One of the bigger concerns is size, because you will need to run between a 30° and a 60° radius in order to give enough camming surface to lock down. When you add the center pin for pulling it together, the diameter of that pin for strength, then the size of the hole that runs through the center and making that hole big enough to run the center pin through the camming surface and then covering the surface with nylon so it doesn't mar the finish, you're starting to get a very large protrusion on the outside of your gun.

[csmith]

I'm following you, Creeky. The intent of my second post was basically to relay I think the only way to get no play/tight fitment in the fashion you're looking for is to start at the production of the receiver. Any aftermarket answer will have to do what the Accuwedge/JP Pins do, and that is to push them apart so there's no play. The only way I can see around not having the loose fitment and simultaneously keep the receivers mated tightly (not pushing them apart) is to lower the take down pin's holes on the lower receiver and for that you have to be the person creating the dies for the receiver at the beginning and also have a meticulous quality control about it, which from the above posts concerning Noveske seems like they do.

[Creeky73]

It's not a bad idea, but there are some engineering challenges that will go along with it. One of the bigger concerns is size, because you will need to run between a 30° and a 60° radius in order to give enough camming surface to lock down. When you add the center pin for pulling it together, the diameter of that pin for strength, then the size of the hole that runs through the center and making that hole big enough to run the center pin through the camming surface and then covering the surface with nylon so it doesn't mar the finish, you're starting to get a very large protrusion on the outside of your gun.

Now this is what I was looking for. I didn't know if it was possible or not, and was hoping someone with a more technical mind than mine could see obvious reasons why it wouldn't work, or might not be ideal.

[Koshinn]

Nevermind. I figured out my brilliant idea was already made.

Ok another idea:
A ratchet screw to extend the center part of the pin and to lock the diameter in place, the ratchet being on the right side. When you push out the take down pin, it slides out from the ratchet teeth and can be loosened the rest of the way. It just requires a custom lower.

Hm.

Ok I have another idea that solves all problems besides being very small. The right side of the receiver has a thumb screw. You press in and it unlocks from teeth on the inside of the pin and can be rotated. It has a spring and slots into a screw that as it extends, makes the middle of the pin larger. It's very complicated but I think it can work. I'll draw it tomorrow if my memory lasts through the night lol.

[LanceCriminal]

Haven't I read that match shooters used to do a thin layer of epoxy or bedding sandwiched between the two receiver halves? IE you mask off where you do not want the epoxy on the insides and on one receiver, then put epoxy on the other half where they mate. Scrape the excess off the outside and inside and let it cure, remove the masking and it should be tighter. But then I guess they just went and made the JP pins and Accuwedge because it could be messy and/or permanently fix your receivers together if you screw it up.

[TheBeef]

http://www.demontactical.com/demon-tactical-quick-p-57648.html

Viola!