General discussion > Black Powder Shooting
Sealing round grooves
smylee grouch:
Some years ago now the Minneapolis Museum of Art had the famous J. Kuntz rifle on loan from the Metropolitan Museum of Art in NYC. One of my daughters lives close by so we made the trip to see it. Alas they had sent the Kuntz rifle back to NY the week prior to our trip. But they did have a Dickert there and I got to see the muzzle up close. The round groves were more, how shall I say up and down and less " valley" shaped like some of the current barrels made. Makes me wonder if the more pronounced " up and down " groves might grip the patched ball better. If so the lands might be wider but if you cut one extra grove you could/would reduce land width I think. I'm also thinking this might make it easier to seal up the bore. :-\
Daryl:
I tried to get a maker of custom rifled barrels to cut one with .008" to .010" depth, but with grooves with rounded corners.
He was of the opinion, that unless a barrel has .025" to .028" depth, it wouldn't shoot & thus, would not make me that barrel.
This type of barrel will shoot well, especially with snug loads. It would also clean up more easily, without sharp corners.
Doubled up flannelette on a jag cleans very well, rifling with normal sharp cornered grooves.
Eric Kettenburg:
^^^
Yes, I know Bob Hoyt's "round grooves" and Rice's "round grooves" look to my eye more like square grooves with a rounded corner and a slight radius to the bottom, like you're describing, and they don't seem crazy deep although admittedly I'm not measuring them. Colerain's grooves are like deep round rain gutters, and the grooves are usually close in width to the lands. Rayl's round grooves are deep and very round, with lands wider than the grooves. The round grooves Getz barrel used to cut were also more similar to Colerain's but I don't think they were quite as deep.
I prefer Rice's barrels to pretty much anything but honestly I've never had a problem with any barrel; however, I'm not a bench shooter and if I can keep my shots in a @ 4" to 5" circle with ANY open sight gun, I'm happy as a clam. But then I don't use tight combos either.
Lots of German guns and definitely some early American stuff seems to have been made with fairly deep, round grooves i.e the MArshall gun, Shreit rifle, a few Dickerts I've seen, and some other stuff as well. Probably all German import barrels on the American work. I don;t think those guys were worried about putting everything into one hole, I think they were worried about "minute of deer" accuracy or "minute of native dude trying to kill me" accuracy.
bob in the woods:
From the research I have done, it seems to me that owning an exceptionally accurate rifle was a real status symbol .
Marcruger:
My experience has been that some round-bottom-grooved rifles can shoot well.
That said, I believe it is much harder to get one to shoot well through load development than a square bottom grooved barrel. Especially if the round-bottom-grooves are deep (like .016" or deeper).
I had one deep round-bottom-grooved barrel that would not shoot no matter what I tried. It was replaced.
Conversely, I have found that Green Mountain barrels (square-bottom) are very easy to find a load which they like. As my target shooting, medal winning friend noted once, "Look at what's on the firing line at Friendship. You'll see a lot of Green Mountain barrels. There's a reason."
He has two .40 Colerain barrels that shoot super. I looked it up and those barrels have .012 shallow round bottomed grooves. They do not have square shoulders to the grooves. Those shoot really well. I think the key word here is "shallow".
I personally see no point in deep grooves, round or square. Just a bother to try to seal.
Just my two cents worth. God Bless, Marc
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