TC Encore barrel stub

[Tincamp67]

I’ve been playing with hoop strength formulas and it seems I will only have about .1” wall thickness on the stub. I’m not sure if that is enough, and not sure if that is included in the overall radius of the chamber area for calculating the hoop strength. Can’t find an answer to those questions. There was a gunsmith in the Midwest who was a guru on this subject, he specialized in encore, contender, and HR/NEF stubbing. He passed away about a year ago and likely took a lot of knowledge with him.

I’ve also looked at photos and videos for a defunct company called Eagle View Arms. They made stubs for Encore and Contender. Doesn’t look like a lot of meat left on the stub, and that is before threading.

I appreciate the input everyone has given and I understand the hesitancy some may have about giving too much detail due to the risks involved. However, this isn’t uncharted territory. When I consider that TC offered Encore barrels in 338 Winchester Magnum, and still only had a 1” diameter chamber, there must be some strength there. And it seems that there are more than a couple of these guns out there and eagle view was selling stubs for gunsmiths and home hobbyist types to. The HR platform has a larger chamber od to work with, so those might be easier. But I don’t have one and they have gone sky high in price since COVID.

 

[mickri]

Have you looked at Roarks Formulas for Stress and Strain. It is the go to handbook for engineers. I consulted it when I was learning how to design free standing masts for sailboats. It has info on hoop stress and probably how to calculate the stress of a pipe within pipe. This is important where two pipes are joined with a sleeve. Older versions are available online for free download.

 

[Tincamp67]

I havent heard of that book. But, it doesn’t take very difficult math to put me over my head.

 

[mickri]

I took a quick look through my copy of Roark,s and didn't see anything about a pipe within a pipe. So you probably don't need to bother with Roark's. The two formulas that keep coming up in my research are Barlows and Lames. Not being an engineer it would seem that the barrel would have to fail before any pressure is applied to the stub. The barrel and the stub may act together. I saw some threads asking this question. Never got an answer. Be interesting to learn what you find out about this.

 

[Tincamp67]

I’m bringing this back for another review. I have an unchambered Douglas barrel in 6.5mm on its way to me. I know that MGM offered the 6.5 Grendel in a Contender barrel and I found someone on another forum who has a savage 250-3000 in a sleeved Contender setup. The Contender has even less barrel shank to work with, and that savage caliber is only a few thousand PSI below the Grendel so I think I’m safe going with the Grendel chambering.

There seems to be much more info available on doing this project with an HR or NEF platform as they have a 1.1” chamber area. But, I don’t own one and they aren’t cheap with post COVID prices, so that’s out.