Round ball ?

[Absoroka]

I shoot a heavy charge in my 32. it has a Douglas 40 inch barrel with square grooves, 1 in 66 twist. It shoots OK with light loads but is a tack driver with the heavy load. Best target result with the rifle was off of cross sticks at 50 yards on the NMLRA small 6 bull. Shot a 50 XXXX. Eyes won't quite do that any more but a 32 will shoot. As far a game damage, it will decapitate a squirrel. Head shots only increases the fun.

 

[Red Owl]

Someone years ago posted a chart of the optimal twist for the caliber. I thought, if I recall correctly, that the 1-66 was for 54 caliber and the rate went down, so maybe 1-48 for a 32 caliber.
I have an odd ball 1-32 "sabot/conical twist and I thought I'd see how round balls do. 50 Caliber. At 50 yards, very well however I dropped the charge down quite a bit.
On pistols, the twist is once again different but I can't recall the details.

 

[Grenadier1758]

@Crow#21957, I just did a quick search of Rice, Colerain, and Pedersoli to see what twist rate they use on the small caliber (36 and smaller). Allow them use the 1 in 48 twist. If I remember correctly, I have seen faster twists in the 1 in 36" used. The small diameter ball and small powder charge stabilize that ball quite adequately. The experience of members of my gun club confirms that. Many hold NMLRA titles at Friendship. They also almost unanimously recommend getting the square bottom rifling.

Now you have me wondering. I'll have to measure the twist rate on my 36 caliber rifles. Have some cores to attend to. The answer will be posted later. One barrel is an Ed Rayl barrel built with a false muzzle. That will be interesting.

@Crow#21957, I measured the twist rate in my 36 caliber rifles. The results are inconclusive.

Navy Arms Mule Ear Twist 1 in 26
Custom Squirrel Rifle with Douglas barrel Twist 1 in 48
Ed Rayle Barrel with false muzzle Twist 1 in 54
SMR unknown Barrel maker Twist 1 in 66

The SMR is quite accurate and uses a fairly stout load for a 36 caliber rifle. 35 grains of 3Fg with a 0.350" ball in my 0.018" drill cloth.
I have shot the Mule Ear rifle but more load development is needed.
I need to do load development with the squirrel rifle and the rifle with the Ed Rayle barrel is getting close to being ready to shoot.

You made the wise choice be selecting the 1 in 48" twist rate.

 

[Scota@4570]

My experience:

A 32 cal Rice with square bottom rifling was a tomato stake. I had it re-bored after about 100 shots of really poor accuracy. The lands were much wider than the grooves. The grooves were pretty deep. IT never had a chance. I should have rejected it at first sight.

32 cal is fiddley to load. IT is also effected by the wind more than a larger ball.

I have and old Kibler SMR 36 cal that shoots well. It think it is a Rice barrel. You can use buckshot in a 36.

A 45 cal Colerain with round bottom rifleing was a tomato stake. I replaced it with a Green mountain after pulling my hair out over it. The grooves were deep and the lands were wide. I think getting a good seal is very important. IF you do not have patch compression in the bottoms of the grooves you are sunk. I have no use for any round bottom barrels.

I have never had a Green mountain that did not shoot. They use wide grooves that are not excessively deep. Their finish is good. I have not had any tonight and loose spots in their barrels. They check off the fundamentals and it shows on the target.

I expect to get 1 1/2" at 50 yards off the bench, double rested with peep sights. If a barrel will not hold the 10 ring on an NMLRA aggregate target then I am not interested.

 

[Uncle Miltie]

Well I got my 40 in 1/48 with 36 in barrel round bottom rifling. Covered tgere. Got my 32 42in flintlock and a 42 in percusion 36. Got a 62 cal fusil kit on the way in couple weeks. Just wanting to build a swamped barrel 42 in southern mnt rifle in percusion. I'm kinda stuck on 32. Since I've got the others I'm covered. So 50 yards I'm dreaming so hopefully 35 would be ok with 32.

My experience:

A 32 cal Rice with square bottom rifling was a tomato stake. I had it re-bored after about 100 shots of really poor accuracy. The lands were much wider than the grooves. The grooves were pretty deep. IT never had a chance. I should have rejected it at first sight.

32 cal is fiddley to load. IT is also effected by the wind more than a larger ball.

I have and old Kibler SMR 36 cal that shoots well. It think it is a Rice barrel. You can use buckshot in a 36.

A 45 cal Colerain with round bottom rifleing was a tomato stake. I replaced it with a Green mountain after pulling my hair out over it. The grooves were deep and the lands were wide. I think getting a good seal is very important. IF you do not have patch compression in the bottoms of the grooves you are sunk. I have no use for any round bottom barrels.

I have never had a Green mountain that did not shoot. They use wide grooves that are not excessively deep. Their finish is good. I have not had any tonight and loose spots in their barrels. They check off the fundamentals and it shows on the target.

I expect to get 1 1/2" at 50 yards off the bench, double rested with peep sights. If a barrel will not hold the 10 ring on an NMLRA aggregate target then I am not interested.

Over the last 35 years I won many prizes with .32 caliber rifles, including the .50 caliber Kibler Colonial I shoot. They do very well if the shooter is up to the task.

 

[Scota@4570]

Saying any caliber is more accurate, or has any special properties, is misguided. It is the dimensions of the rifling that matter. The hole has to be the same size throughout or slightly choked. Tight and loose spots or a flair kills accuracy. The interior finish must be decent. The rifling must be made so that decent patch compression can be had on the lands and grooves. Normally that is best achieved with narrow lands and wide grooves. The depth of grooves must not be excessive. The twist rate does not matter very much as long as it is reasonable.

What annoys me is a barrel maker who does not understand what makes a barrel accurate. One in particular tried to tell me that wide lands and narrow deep grooves was just fine and would be as accurate as any other. The truth is that skinny grooves and wide lands are easier to cut.

 

[Crow#21957]

Saying any caliber is more accurate, or has any special properties, is misguided. It is the dimensions of the rifling that matter. The hole has to be the same size throughout or slightly choked. Tight and loose spots or a flair kills accuracy. The interior finish must be decent. The rifling must be made so that decent patch compression can be had on the lands and grooves. Normally that is best achieved with narrow lands and wide grooves. The depth of grooves must not be excessive. The twist rate does not matter very much as long as it is reasonable.

What annoys me is a barrel maker who does not understand what makes a barrel accurate. One in particular tried to tell me that wide lands and narrow deep grooves was just fine and would be as accurate as any other. The barrel being discussed was the 32 in my pervious post. The truth is that skinny grooves and wide lands are easier to cut. I will never buy another barrel from him.

 

[Crow#21957]

Scott could you pm me. Thankyou

 

[Red Owl]

Scota- I always sort of thought the same thing, why should one caliber be any more accurate than another. On the 40 caliber, all I could think is maybe the smaller hole, on a barrel of equal diameter, creates a more solid barrel. I don't really know. Another thing, since most barrels are 1 in 48, maybe that just works very well with a 40 caliber ball.

 

[Kansas Jake]

In a 32 powder usage will not be an issue but generally speaking a slower twist requires higher velocity (more powder) to reach best accuracy. A 32 isn’t really a long range gun. I’d go with 1in48 as Oldwood suggested.