Back to Back 7.62 NATO Pen

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Sylvanite

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Jul 18, 2006
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3,090
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Hillsborough, North Carolina, USA.
I had a customer request some pens made from back-to-back rifle shellcases. His requirements were:
  1. both shellcases must be 7.62x51mm NATO caliber;
  2. the nosecone must be a real bullet; and
  3. no centerband.
I imposed the additional requirements:
  • the bullet must be seated to SAAMI specs (in order to look real), and
  • the Cross-style refill cannot be modified (so it can be replaced by the owner).
Normally, I make back-to-back shellcase pens with a 30-06 Sprg cartridge lower barrel, and a 308 Win shellcase upper barrel. I find that combination of calibers works well. The above requirements, however, necessitated some design changes.

This photo shows how I make my 7.62 NATO (and 308 Win) cartridge pens:

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With a bullet seated to the correct overall length, the cartridge is too short to take a stock Cross-style refill. Many people overcome this hurdle by either
  1. seating the bullet about 3/16" long, or
  2. shortening the refill.
My personal requirements above, however, prohibit these approaches. My solution is to solder in the brass tube with about 3/16" protruding from the case head. I press the transmission into that. When turning an upper barrel from wood or plastic, I simply recess the tube by a corresponding amount.

When I use a 30-06 cartridge for the lower barrel, the tube is soldered flush with the case head, as is the 308 upper barrel. There is a gap between the tube and the case mouth (at the finial end), which I typically fill with a piece of shrink tube (applied before soldering). I couldn't do that this time. The upper barrel tube has to be recessed.

So, I needed to solder at the case mouth instead. Solder won't fill the gap, though, so I had to come up with something else. I wound up using a slimline centerband. I reamed it out with a letter "E" reamer; soldered the centerband to a brass tube at the appropriate location; turned the centerband down to the correct diameter; soldered the tube to the case mouth; and then trimmed it to length. Now the upper and lower barrels will meet.

That then posed another problem:

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When retracted, the refill sits nearly flush with the upper barrel case mouth. There's no room to press in the finial. I solved that issue by reverse-mounting the finial in a collet chuck and drilling a recess for the refill:

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Now the parts all work together when assembled. The finished pens look like this:

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And the customer is happy.

I hope that was instructive,
Eric
 

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Sylvanite

Member
Joined
Jul 18, 2006
Messages
3,090
Location
Hillsborough, North Carolina, USA.
Some additional pics

When I first posted, I couldn't find all the in-progress pics I took. I've since uncovered them so here they are:

This photo shows a slimline centerband soldered on a 7mm tube, and one turned down to the case neck inside diameter:

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Here is a picture of the above tube fit into the shellcase, and one with the tube soldered in and the excess trimmed off:

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And finally, here is a shot from the case head end, showing that the tube is recessed about 1/4" up into the shellcase:

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I hope they help illustrate the process,
Eric
 

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Sylvanite

Member
Joined
Jul 18, 2006
Messages
3,090
Location
Hillsborough, North Carolina, USA.
I may have to go to the range this weekend and empty a couple of 300 savage shells to play with.
300 Savage is a little shorter than 308 Win / 7.62 NATO (about 0.1"-0.15", depending on the bullet). Therefore, you might need to extend the tube a bit more, and recess the upper barrel tube a corresponding amount.

I hope that helps,
Eric
 

Cmiles1985

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Joined
Nov 12, 2013
Messages
1,611
Location
Aransas Pass, TX
I may have to go to the range this weekend and empty a couple of 300 savage shells to play with.
300 Savage is a little shorter than 308 Win / 7.62 NATO (about 0.1"-0.15", depending on the bullet). Therefore, you might need to extend the tube a bit more, and recess the upper barrel tube a corresponding amount.

I hope that helps,
Eric

Thanks for the info! My idea is this: I have a shoulder mount deer in my attic that is coming apart (nowhere in my house to hang it); it was my grandfather's. I now have my grandmother's 300 savage and one of my cousins has my grandfather's 300 savage. What I want to do is make a combo antler/300 savage casing pen for all of the decendants of these grandparents (6 pens total). Needless to say, I'll be doing some experimenting before using the antler I have!
 
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