PRS Tubegun

jbolt

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Dec 3, 2013
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Had some vacation time these past two weeks so I made some good progress on my PRS gun. Having never actually seen one up close the tubegun chassis was modeled in Solidworks based on photos of commercially available ones.

Cad Model

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I took initial measurements off my M700 receiver and then verified the fit by 3D printing the tube for the receiver and the magazine well.

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Once I was satisfied with the final measurements and 3D models the parts were machined on a combination of my lathe, CNC mill and heavy duty drill press that has milling capabilities. The only machining I documented was the setup for boring the receiver tube which is 10 inches long. This was made from 2" OD x 1-1/4" ID 6061 extruded tube. Finish ID is 1.365" which is a slip fit for my receiver. The 1 inch boring bar was not long or rigid enough to bore full depth so the part was bored half way and then flipped.

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Here is the completed and assembled gun ready for demurring and powder coating. I'm going to do the powder coating myself once the powder coat gun I ordered is back in stock. I still need to make a drum tumbler to do the deburring for the larger parts that will not fit in my vibratory tumbler.

M700 short action that I have trued.
PT&G magnum face bolt with handle tig welded on.
GTR firing pin assembly
TriggerTech single stage trigger
6.5mm MuellerWorks 4 groove barrel in heavy varmint taper finished at 28"
Chambered in 6.5 SAUM
APA LB brake
Magwell machined for AICS style magazines.
Barrel guard machined with M-Lok pattern.

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Beautiful rifle. I think that these tube rifles are cool looking and I may make one someday. I often wonder what do you actual gain by mounting the receiver in a tube.
 
Nice looking work!
Is the receiver set-screwed in the chassis tube?


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Beautiful rifle. I think that these tube rifles are cool looking and I may make one someday. I often wonder what do you actual gain by mounting the receiver in a tube.
Thanks mickri. The main argument I have read is that the tube gun uses a round recoil lug which distributes the recoil energy equally around the receiver and chassis. Being that the majority of competition rifles are not build this way I'm not sure it matters.
 
Nice looking work!
Is the receiver set-screwed in the chassis tube?


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Thanks sgisler. Traditionally the receiver is fully epoxied into the receiver tube. Because I chose not to epoxy mine in place the receiver uses the action screws with additional brass set screws. I'm not 100% sure why this is done but the commercially available tube chassis are made this way if the receiver in not epoxied in. Since they have way more experience with these than me I put them in. My guess is that the commercial chassis are bored oversize to account for the variation in receivers. I was able to make mine a snug slip fit so they may not be entirely necessary.
 
That is stunning. How can you bring yourself to hide that with powder coat?!
Robert
 
Thanks sgisler. Traditionally the receiver is fully epoxied into the receiver tube. Because I chose not to epoxy mine in place the receiver uses the action screws with additional brass set screws. I'm not 100% sure why this is done but the commercially available tube chassis are made this way if the receiver in not epoxied in. Since they have way more experience with these than me I put them in. My guess is that the commercial chassis are bored oversize to account for the variation in receivers. I was able to make mine a snug slip fit so they may not be entirely necessary.

That all makes sense, thanks!


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That is stunning. How can you bring yourself to hide that with powder coat?!
Robert

In his shoes, I'd powder coat it or cerokote it to a clear finish. That thing is gorgeous.
 
I agree it needs some protection to be usable. It's just so awesome looking as it sits!
Robert
 
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