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Upper and lower Fit


StravIs09

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Whats up raging 3gunners!

Alright I recently did a build and it turned out pretty awesome, individually I really like all of the components that went into the build.

nordic 16" barrel

midwest gen 2 key mod 15"

pri brake

syrac

smooth gizzle trigger (highspeed national match)

bad safetys

A5 and emod stock set up.

the issue and one thing holding me back from loving this rifle build is how loose the upper and lower fit. it feels like a cheap Ak that rattles around on the pins.

The lower is by itself absolutely awesome and comes equipped with a tensioning screw in the back of the receiver but to get the upper tight the screw is 1/4" exposed and feels very lose and doesn't stay set. The adjustment doesn't stay set for more then a few minutes it seems and before I make it to the range or even put any rounds down range the upper and lower are very loose.

I know that this has almost no effect on the function or accuracy of the rifle but it just doesn't feel like a top notch gun.

Options

1. accu wedge- although this might be the best/cheapest option to fix the issue I just dont like the gap in the upper and lower that it would create.

2. lock tight the tension screw and hope it sticks. still it creates a sizable gap in the upper and lower

3. drill and re- tap the screw to a much bigger size for strength rigidity

4. machine some collets to press into the upper receiver and adhere some shims to the upper receiver so that the pins fit snug and firmly attach the upper to the lower.- leaning towards this option. maybe the most costly..

What do you all think?

Thanks

Sam

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Get a longer set screw that has a nylon insert in the thread to keep the screw from turning itself out.

McMaster-Carr should have them. There will still be a gap but should fix the rattle.

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If the gap really bothers you you can bed the upper to the lower with Accra-Glass gel. Put a wedge in it to spread the upper and lower where it is tight. put release agent on the lower, degrease the upper and put the bedding compound on the upper and put it together. Use black dye and you will never be able to tell there was a gap and it will fit nice and tight. I have done quite a few this way over the years and it works great.

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If the gap really bothers you you can bed the upper to the lower with Accra-Glass gel. Put a wedge in it to spread the upper and lower where it is tight. put release agent on the lower, degrease the upper and put the bedding compound on the upper and put it together. Use black dye and you will never be able to tell there was a gap and it will fit nice and tight. I have done quite a few this way over the years and it works great.

I've done the same thing using a feeler gage to set the proper pin tension, and Bisonite for the epoxy. The recievers are still tight after years.

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A JP Tension Pin is an option for you.

This is something i am now interested in.. Thanks

Loctite the tension screw.

See if a Quentin Defense tension screw will fit, if you are using say a Sun Devil lower. They have a nylon head and are pretty long.

Mick

Not a sundevil, i picked it up off your good friend stealthy at smm3g if that helps give you a better understanding without trashing a company on a forum

I wish someone would make their uppers and lowers with undersized rear takedown pin holes. Then we can finish ream them after assembly for a perfect fit.

that would be sweet, a gunsmith style fit

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Get a longer set screw that has a nylon insert in the thread to keep the screw from turning itself out.

McMaster-Carr should have them. There will still be a gap but should fix the rattle.

I will measure the set screw and probably order tomorrow. Thanks

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Get a longer set screw that has a nylon insert in the thread to keep the screw from turning itself out.

McMaster-Carr should have them. There will still be a gap but should fix the rattle.

local companies as well as McMaster-Carr did not carry a longer set screw. It will be a hard task to get a screw in the same thread with a platic insert.

Just Loctite the tensioning screw - that is what it is for.

I'd rather have to do that or use an Accu-Wedge than have to use a hammer & punch to pull them apart like I do on my Noveske/VLTOR combo.

lock tite on the set screw in the current condition will likely not hold as the set screw is barely threaded into the receiver because of how far it needs to stick out to even touch the upper receiver.

Accuwedge will have to be the ticket.

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Accuwedge is better than nothing but doesn't compare with the JP Tension Pin. It is, however, much easier on the wallet and doesn't make it any more difficult to take the gun apart.

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Talk to the maker of the lower and see if they have a longer set screw you can use.

Come find me at this Saturday's 3 Gun match and I will have a Quentin plastic tipped screw with me that we can see if it will fit your lower.

Mick

Get a longer set screw that has a nylon insert in the thread to keep the screw from turning itself out.
McMaster-Carr should have them. There will still be a gap but should fix the rattle.


local companies as well as McMaster-Carr did not carry a longer set screw. It will be a hard task to get a screw in the same thread with a platic insert.

Just Loctite the tensioning screw - that is what it is for.


I'd rather have to do that or use an Accu-Wedge than have to use a hammer & punch to pull them apart like I do on my Noveske/VLTOR combo.


lock tite on the set screw in the current condition will likely not hold as the set screw is barely threaded into the receiver because of how far it needs to stick out to even touch the upper receiver.

Accuwedge will have to be the ticket.
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