Rifled bores - what are their actual dimensions?

[BattleRifleG3]

We know how large each smooth bore measurement is for a shotgun gauge.  But what about rifled barrels for slugs?  Is the 12ga measurement the diameter of the grooves or the lands?

Wondering what people know about this.

[Cat Whisperer]

Handi-rifle in 20ga fully rifled barrel - groove diameter is exactly 0.625" - grooves are something like 0.004 or so deep.  VERY convenient to have a standard size.

[BattleRifleG3]

Thanks very much for the reply.  If that's the case, how do you think one of these would do in a 20ga rifled barrel, in 0.618" caliber?
http://www.barnesbullets.com/products/rifle/banded-solids/

[Busta]

Thanks very much for the reply.  If that's the case, how do you think one of these would do in a 20ga rifled barrel, in 0.618" caliber?
http://www.barnesbullets.com/products/rifle/banded-solids/

At 900 grains (2.06 ounces), I don't think so. The heaviest factory load I know of for a 20 ga is 1.25 ounces. A shotgun barrel is not a 'rifle' barrel, even if it is rifled.

[IOWA DON]

My 20-gauge slug gun has a 1-in-24 inch twist rate and stabilizes 720-grain cast lead slugs at 1,000 fps. I use AA5700 powder and turned brass cases from Rocky Mountain Cartridge Company and get good groups at 50 yards.

[BattleRifleG3]

Sounds like the kind of thing I'd go for!  Where do your slugs come from?  Do you cast them yourself?

I actually have a hankering to use black powder in such a loading.

[IOWA DON]

BattleRifle - Yes. I use an NEI Handtools bullet mold. They sell one for 900 grain bullets intended for the .600 Nitro Express. They made tis one to the same diameter but eliminated one of the lubrication grooves and bullets weigh about 720 grains. I use pure lead as the pressure is very low. A few bullets cast with wheel weight alloy seemed to lead the bore. I guess they were too hard to seal the grooves. I have also had some hollow-pointed with a deep hole with a 3/8th-inch drill so the weight would be 540-grains for a velocity of 1,200 fps. Both the 720-grain solids and the 540-grain hollow-points will kill deer. I've gotten one deer with each bullet, but prefer Hornaday or Winchester sabot slugs for their much greater range. Also, the heavy lead slugs are fun to shoot, but I think very prone to ricochet. - DON

[Cat Whisperer]

Thanks very much for the reply.  If that's the case, how do you think one of these would do in a 20ga rifled barrel, in 0.618" caliber?
http://www.barnesbullets.com/products/rifle/banded-solids/

I don't know about the Barnes.  No point of reference.

But, there are folks that have used lead banded with copper tubing - swaged - very effectively.  That is something that I'll try someday as well as making my own mould.

FWIW pvc 1/2" tubing is exactly .625" on outside diamter.  It engraves fully when fired.  It is tubing, so building a bullet from it is problematic.