Currently converting a Siamese Mauser to 450 Marlin. Through out my search for barrels I came across the GM Octagon barrels. Has anyone here had experience turning one the barrels down to make a 1/2 Octagon 1/2 round barrel? I imagine they aren't all that bad, but I wanted to hear it from the proverbial "Horses' Mouth".

Adam

They're excellent barrels. Known for high potential for BPCR and Long Range Blackpowder rifle competition.

If you want a half round/half octagon, I've got some 30 inch ones that would be excellent for what you propose, although heavy. I'd sell one for $225, shipped to you. As I recall they're about 1" at the muzzle, and will finish at 28 or 29 inches. I had them custom contoured from Montana rifleman blanks, and have built several very competitive BPCR rifles with them. They're excellent shooters. The best thing is they were sanded to about 250 grit, and then bead blasted. They take very little work to finish.

dave

Dave I appreciate the offer and if I go that route I certainly will entertain your offer. Though currently I am probably going to with a #4 contour to keep the weight down. Although I haven't made any hard choices.

Adam

Be aware that on the Green Mountain Barrels, the #4 barrel is a #4 Winchester High Wall Profile, 1 1/8" across the flats or so. Very heavy barrel. The barrels I have are a similar profile, I just checked and one weighted 7 lbs 5 oz.

Green Mountain doesn't make a lighter barrel in .45 cal, their intended use is heavy long range blackpowder cartrdige rifles in .45-70, .45-90, etc.

To get a lighter profile, you have to order one from McGowen or similar that will make a custom octagon profile.

dave

Thanks Dave, I was aware of the contour differences, but for those who aren't it could be a "heavy" pitfall

#4 is the lightest contour most mfg's will make a .458" barrel

Adam

Specifically, the GM #4 Winchester barrels are 1-1/8" at the breech and 1.08" or so at the muzzle.

Clarence