barrel contour: is it ALL personal preference? (chamber area only)

[Whiterabbit]

Hello,

Here's a pic of the pacnor custom contour chart:



Specifically, I'm interested in items "D", "E", and "B". (And R, technically)

Are these, like length and muzzle diameter (within reason), fully up to the buyer as an aesthetic choice? Or is there really important reasoning behind the values assigned to these that must be met for safety reasons?

[Whiterabbit]

Well, I see that CZ barrels their 500 jeffery and 505 gibbs guns with an "E" value of about 5 inches total. About. So it seems like I can go as aggressive or small as I want without fear of safety as long as I go with a suitably fat tube.

I picked a pretty short chamber area, <4 inches. for the main barrel length it will be fat, .945 inches. This surpasses most African rifles made by the likes of CZ and kilimanjaro. Seems like I'll be just fine.

[Bent Ramrod]

In the old days when they were cheap and plentiful, the 1917 Enfield was used to make a lot of magnum rifles on account of its generous size. The gunsmithing articles always said that if one planned to go to .300 Magnum cartridges, rechambering the military .30-06 barrel was a poor idea because the reinforce (the "D" width) did not go out far enough (the "E" length) to give the proper amount of metal around the front of the magnum chamber. A new barrel with proper proportions was necessary.

So if you have a long, high intensity cartridge, you would need a long "E" section to match. And enough "D" diameter, of course.

[Whiterabbit]

common sense tells me that. I was pinging the cast booliteers to help put numbers to that, if needed.

[Willbird]

I know that when you move the pressure curve DOWN the barrel, like when you build a smokeless muzzle loader, where the "cartridge" even though it does not exist could be thought of as a long skinny one, some folks have reported bulging barrels with some loads/calibers/contours.

They also usually do not suggest 416 stainless barrels in really skinny contours for cold weather hunting.

Bill

[Whiterabbit]

Well, I ordered the barrel, and I think the contour I picked will do me just fine. The chamber area will be a copy of the existing rifle, "about" 1.2" in diameter starting at the action face and extending out roughly 1.5 inches. Then it will neck down to .945 inches fairly rapidly, maybe 1.8-1.9 inches from the front of the action. Then it will remain .945 inches straight out to the muzzle, no taper. The cartridge is .510 wells. Been dreaming about this rifle for years. Barrel should come back just after Christmas.

Should make opening up the barrel channel very straightforward.

It's alloy steel, not stainless. I want a blue gun.

[Willbird]

Last barrel I ordered "6 weeks" turned into "3 months", from Shilen.

Bill