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Posted: 10/29/2004 6:26:25 PM EDT
| I just tapped my 80% forging and the threads are not very deep. just wondering if the inside of the buffer tower is supposed to have peeks or be smooth. Thanks for any help. |
Actually, it's not. My first 80% was a KT, and it certainly wasn't tapped. It was started for a tap, but I still needed to run the tap through it. For ease of building, the best I have found so far have been the HPS receivers from www.ar15plus.com/. I've built two of those, one from Shadtree Armory, and the KT. |
how did you like the shadetree compare to the HPS ? I have a HPS, thinking of getting a shadetree for my other build... |
Is there a chance there was an older model from KT? Cuz the website doesn't mention tapping as something that needed to be done. And that picture sure looks like the threads are complete. It just said there was just drilling and milling out the mag release slot. |
Actually, what you don't see is that the mag release slot isn't cut yet like other 80% receivers. Nor is the front pivot pin fork cut yet either. I just figured that since they tapped the receiver extension already, and spot drilled the major holes, that they had to compensate in other areas. You can see how spot drilling greatly reduces the chances of a screw up. |
true |
You're right, however in that pic it showed the front pivot pin fork already cut and the hole already drilled, that's what lead me into believing that it's actually a picture of a complete receiver. |
You need to ream and tap the buffer tube thread, drill the take down pin hole, hammer/trigger pin hole, selector hole, all detent holes, and the stock index. The fire control area will need to be opened up for the parts to fit. Upper will not fit without opening up the rear lug area first. You can alternatively shave down the trigger parts. However you will still have to mill out the rear take down lug area, unless you're willing to permantly shave down the take down lug on your upper. All in all the HPS the easiest 80% receiver to complete. |
| I to am using the Hps receiver, i guess when i started to ream the buffer tower i didn't have it clamped down all the way. The drill i was using on my 1/2" drill press was the correct one(1 1/8"). It might also be that i can't seem to change the speed on the press, so the bit was going to fast. So thanks for your help. |
The Shadetree receiver required a lot more work than the others - I'd call it a "60%" and not an 80%, This was their "stage 3" unit, BTW. In addition to the operations needed to finish the HPS receiver, the Shadetree required milling the pistol grip area to final size, finishing the radius for the buffer tower, and milling the bolt stop area. None of these is a big deal if you have a mill, but it does take longer. I can't see how you'd complete it without a mill. |
Funny you should ask - I just finished another one with my mini mill. The following is a list of steps I wrote up before doing the first one so that I wouldn't have to "rethink" the whole process each time. I don't have tool sizes listed though, which would be helpful, but those are always available off the blueprints. 1) Mount drill chuck - Drill pivot pin hole - Drill remaining holes w/jig - Drill bolt catch plunger hole 2) Mount 3/8 end mill holder - Mill fire control area to final size - Mill rear takedown pin relief - Mill buttstock retainer hole 3) Mount 1/2 end mill holder - Mill buffer hole to final size 4) Mount 3/8 end mill holder - Tap buffer tube hole 5) Mount drill chuck - Drill rear takedown detent hole - Drill selector detent hole - Drill pistol grip screw hole - Tap pistol grip screw hole - Drill pivot pin detent hole - Drill pivot pin detent drain hole - Drill bolt catch pin hole - Drill buffer detent hole |
I can't dispute this, but I'd add that I've had good results with a 1.125 end mill, stepping up from smaller sizes. While the hole won't be as perfect as that produced by a reamer, it is darn close. The last receiver I did using this method had the hole vary from 1.124" to 1.126" as measured by my calipers - I think that's good enough for government work :). I don't recall what the tolerance on the plans are - anyone got that handy? Actually, if I had the proper size reamer and set up tools to use it, I would go that route. However, I don't, so I've just fallen back on using the end mill. Lots of lubrication and a square and secure setup has worked ok on the HPS and Shadetree lowers. |
I'm using the excellent jig found at CNC Gunsmithing. You could certainly do it without, but it does make things go quicker and helps to eliminate errors. I have a Micro-Mark mini mill - it's the same basic unit at the Grizzly and Harbor Freight, except that the X/Y dials are calibrated so that one turn = 0.05". Good luck! |
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