advice about a new barrel

[WayneT]

I requested a quote form a barrel manufacturer.

My Specifications were:
45 Cal. Straight Octagon Barrel, 7/8" across flats, 36" long, 1:56 Twist, .008 round bottom rifling

The comment from Barrel manufacturer was:
I have a question concerning the rifling depth. Round bottom rifling is deeper than you have requested. My round bottom rifling is .014-.016 deep. My square bottom rifling is .008-.010 deep. The extra depth of the round groove increases the area for the fouling. Making it easier to load. Also with a depth of .008 the lands are going to be very wide with the groove being narrow. This will increase the bearing surface on the patched ball and make it harder to load. I would recommend that you go with the standard depth.

Any comments from the muzzleloader forum would be appreciated

 

[necchi]

I would follow the barrel makers recomendation.
He's in business because he's making good barrels. In this business a poor barrel maker does not last long, it's a niche market to begin with and word get's out really fast about bad custom barrels. :idunno:

 

[paulvallandigham]

I agree with Necchi. The big restriction in your choice of barrels begins with the caliber. That .45 cal. is a "small bore" for round bottom rifling, in that size barrel. Take the advice of the barrel maker. He knows what works. :thumbsup:

 

[longcruise]

Or, go with the sq bottom rifling. As good as round bottom is, seems that competition shooters tend to prefer sq bottom.

 

[Dphar]

I requested a quote form a barrel manufacturer.

My Specifications were:
45 Cal. Straight Octagon Barrel, 7/8" across flats, 36" long, 1:56 Twist, .008 round bottom rifling

The comment from Barrel manufacturer was:
I have a question concerning the rifling depth. Round bottom rifling is deeper than you have requested. My round bottom rifling is .014-.016 deep. My square bottom rifling is .008-.010 deep. The extra depth of the round groove increases the area for the fouling. Making it easier to load. Also with a depth of .008 the lands are going to be very wide with the groove being narrow. This will increase the bearing surface on the patched ball and make it harder to load. I would recommend that you go with the standard depth.

Any comments from the muzzleloader forum would be appreciated

Buy a Green Mountian and forget the round grooves. Round grooves are OK to look at I suppose but I don't know what the advantage would be and if over .012 deep its impossible to get a patch to reasonably seal the grooves. In a 50 caliber .018 patch, ball .005 under bore makes for a uncompressed diameter of .531". In a bore with a .016 deep grooves the groove diameter is .527" This gives .004 total or .002 per side compression in the groove bottom.
A .010 groove will give about .016" compression.
IMO you idea of .008 grooves round ot "square" is correct. But the barrel maker will likely have to made a cutter to do .008 grooves and maintain his land/groove ratio. Cutting .008 with a cutter meant for .016 will result in wider lands an barrel that will load hard as he states.

The one in 60 twist from GM will perform identically to a 56.
The "extra area for fouling" is just BS.
Though I suspect the patch does not wipe the deep grooves well when loading.

Dan

 

[Bill Hall]

Makes sense to me. If the radiused cutter is set shallower, the devoloped length of the radius is shorter, making the lands wider.

I have a rifle with a barrel that has six grooves, and wider than normal lands, and I hate that barrel! Real pain in the you-know-what to load. The patch thickness needs to be thinner than normal to load easily, and sometimes requires a wad of some sorts with hotter loads. When a sturdier thicker patch is used, it is very difficult to load.

Sounds like if you want shallow rifling, square bottom is the way to go. If you want the round bottom rifling, then you need to go with the depth he quoted. You don't want to end up with extra wide lands. Bill

 

[texcl]

If we are speaking about a rice barrel I would go with the round bottom and take his advice, he knows what he is talking about and makes the best barrels out there, my round bottom barrel loads and cleans way easier than my flat bottoms and it is the most accurate and consistant barrel I own.