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I'm trying to make a center support using a 5/16 bolt (7.62X39 method) for a screw build and wondering how do you ensure you're drilling the screw hole in the center without using a lathe? What other methods to build a center support are there other than using a bolt and tapping it? Thanks!
 

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I've heard of using brake tubing with a long screw through the center as a center support. Short lengths of brake line can be purchased at Napa or other auto supply stores for a couple bucks.

You could also find short lengths of steel tubing at welding supply houses or maybe even hobby stores.
 

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I used a roll pin and a long 6-32 screw with a cap nut on my first build. Just how important is the center support anyway? If your receiver was strong enough would you even need it? Just a question....
 

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I have used 3/16 and 1/4 inch rod without any problems. I just cut it to the proper length, put it in a vice and center punch the ends and drill it and tap it. Even if you have a receiver that is rigid enough to get away without the center support, I recommend using one anyway because it also acts as a hammer stop, keeping the hammer from striking your lower rails and bending them up when you do not have the bolt carrier in. I have also used 1/4 roll pins with good results. ak'sr4me
 

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Toj said:
I'm trying to make a center support using a 5/16 bolt (7.62X39 method) for a screw build and wondering how do you ensure you're drilling the screw hole in the center without using a lathe? What other methods to build a center support are there other than using a bolt and tapping it? Thanks!
A 5/16 transfer punch works great to find the center.
Use a piece of wood or anything else with a 5/16 hole in it, as a collar to line up the punch.

But it doesn't have to be dead nuts, you could probably eyeball it, if you don't have a set of transfer punches.
 

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I like Cephus's method best. Just reserve the suds for AFTER, to lessen the chances of boogering it up.
 

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How come ya'll are not using the cross member and bushing? Isnt it just a rivit with a bushing?
 

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I messed up my center support location I drilled to high and had to redrill its a little lower than it should be now, i was wondering if its required for the lower rails to be connected to the center support. Or could I get away with just grinding away the predrilled part of the rails for the center support? Is the emtpy hole on top of the new center support location gonna cause any problems? Also my selector lever on the left side the rounded side dosent let the bolt carrier clear its about .500 of an inch to close on the left side only. Can I get away with grinding a little of the selector lever just enough to clear the bolt carrier.
Or should I throw it in my collection of failed receiver blanks?

thanks.
 

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alf004 said:
... Also my selector lever on the left side the rounded side dosent let the bolt carrier clear its about .500 of an inch to close on the left side only...

I'm having a little trouble trying to picture what you are saying, do you have a pic?

Also is it correct, that you are saying that it is off by a half inch?
 

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Toj said:
I'm trying to make a center support using a 5/16 bolt (7.62X39 method) for a screw build and wondering how do you ensure you're drilling the screw hole in the center without using a lathe? What other methods to build a center support are there other than using a bolt and tapping it? Thanks!
Toj, shoot me your address and I'll mail ya a piece of tubing that is the perfect size. 4130 steel . . . left over from the BuildFest.

I'll cut ir at about 1.25" . . . you can trim to size. 1.182" is usually perfect for me.

Disconnector
 

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I was going to recommend Scott at DPH for center supports at $2.50 a pop but it looks as if he is out of them, as I cannot find them on his sight anywhere. I do not care for the rivet that he has for them, for one thing it appears to only be offered in his set of rivets (not individually) and the head on it looks more like a thumb tack than the traditional round head rivet that you would expect. That is not a problem as you can purchase a one pound box of 3/16"X2" rivets from McMaster-Carr for less than $10.00 shipped to your door. At one rivet per receiver a one pound box will go a long way. The only hang up with it is the holes in the receiver and the support itself are 5/32" in size so it would be necessary to open everything up about about .030" to make it work. I wish a guy could just buy 5/32"x2" rivets in bulk but apparently they are not an off the shelf thing and you had better be ready to buy them in quantities of 25K or more if you want them.
 
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