H&A underhammer twist??

[Ray P]

Anyone know the bore twist in a .36 cal Hopkins & Allen underhammer rifle?

[Jim Watson]

Not me.
Do you have the gun in hand?
Do you have a swivel handle cleaning rod?
A tight patch, a piece of masking tape, and a magic marker will let you determine the actual twist. Put the tape on the rod like a little flag, start the tight patch in the barrel and make a mark on the rod at the muzzle. Advance the rod until the flag goes around once, make another mark. Pull the rod out and measure the distance between marks.

[Omnivore]

Or if it has a very long twist, measure the length of a half turn, then multliply by two.

You can eyeball the twist rate of some guns. Look down the bore of a Pietta '58 Rem NMA for example, and you see about a quarter trun. The Pietta has about a 30" twist.

You want to know the twist of your rifle barrel because that's an indication of the projectiles that will work best in it. It's a starting point, but to really know, you have to do some shooting. There are some surprises out there.

[72coupe]

You really can't tell for sure unless you measure it yourself. There is a batch of AR15 barrels out there that are advertised as 1/8 but actually are closer to 1/9.

This has caused great consternation and gnashing of teeth.

[Jim Watson]

Yeah, there was a guy on another board who measured a .243 at 7" when cataloged at 9.25".

Thinking about it, I would expect a slow twist. When the H&A underhammers were on the market in the 1960s, it was just accepted that anything but a rifle musket would be shot with a patched round ball. The Maxi Ball and other muzzleloader bullets were yet to come. The late 19th century picket ball and slug guns were not much remembered.

[Omnivore]

The Minie ball has been around continuously since the 1860s. Reportedly, due to the weight distribution, they also tend to do well from barrels with slowish twists that wouldn't normally stabilize such a heavy bullet. They're a totally different animal, compared to the later maxi ball.

[Jim Watson]

The Minie ball was introduced for US military service in 1855, the British were two years ahead of us. The French had been working with it since at least 1849.

But I strongly doubt it was much used in .36 squirrel rifles or close reproductions.

[Ray P]

Thanks, all!

Gun is in ME, but I hope to have it in hand here in WA in a week or two.

Excellent idea, Jim Watson. I'll put your method to use when the gun arrives. May as well put off buying projectiles til I know where I want to start.

Besides, the big blackpowder gun-show in this area doesn't happen til February, so I have time to think & plan :-)