doublegunshop.com - home Forums General Discussion Double Rifles, Paradox Guns & Gauge Rifles @ doublegunshop.com Looking for bore rifle accuracy info

I own and shoot two different 16b SxS bore rifles, both of them sport fully rifled barrels and express sights.
I shoot roundball.
I haven't been fiddling with them lately, but the first image here is of my first day out with one of them, note the two holes on the lower left corner of the cardboard target backer.
Those are the rifle's first breaths in over a hundred years, shot at fifty yards.
The following images are from a J&W Tolley catalog.











--Tinker

Tom,

Think about this for a second. If you shoot a round ball from a smooth bore barrel, you are shooting a musket. If you shoot a round ball from a rifled barrel you are shooting a rifle. The early muskets were often shot with out patching during war to save time loading. Hence the need for long lines of shooters facing each other.

When I did a lot of black powder rifle, the trick to accuracy was properly patching the ball so it engaged the rifling and prevented any blow by. The rifled shotgun slug was developed to help stabilize the slug by imparting spin. The skirt expands to prevent blow by. The minie ball kept the skirt in the design for the same reasons.

It sounds like your slug is not being stabilized, hence the large groups down range. A black powder rifle shooter with a decent gun can eventually work up a round ball load with patching that can achieve 1/2" groups at 100 yards.

Back from a few days away for the holiday.
Thank you all for the great info, although being "urgently advised" to buy a Tolley sounds like a hard sell.
Those vintage adds really answer a lot of the basics regarding what was available and to some extent what they were capable of.

I have been shooting black powder for about 12 years and I was originally going to make a ball gun.
I am sure that I will end up with something that works but I also wanted to look at all of the options. (most of which are around 100 years old).
As far as stability, I know that there are cases where a bullet is accurate at close range and less accurate further out (and the opposite can be true as well)but I don't think that this is one of those cases.
Range will be open in three weeks or so.
I'll have the loads ready by then.

Cheers.

Tom

PeteM:
This is simply not true, mate. The 'rifling' on the slug is to allow a crush-fit through the choke without raising pressure. Actually, it's not rifling at all: the fins are simply angled so that lead smeared off the fins as they are crushed in the choke is wiped into a space behind the fin, so the build-up doesn't raise pressure further. Invented by Wilhelm Brenneke I believe. Brenneke's tests showed that a 'rifled' slug rotates about one turn in 50 metres, certainly not enough to spin-stabilize the projectile. Smooth-bore slugs depend on the 'shuttle-cock' principle for stabilization, in one form or another (either attached base-wad or hollow rear skirt, or sim.).

Wikepedia perpetuates the mis-information about rifled slugs spinning to stabilize, but the Brenneke web-site will set you straight.

Hope this helps.

Bit of apples and oranges here: the Tolley Ubique is a choke-rifled gun, not a fully rifled gun and fires the Fosbery conical projectile of about 535 grains or so. Chokerifled guns usually weigh in at 7 lbs and 4-8 oz. whereas, the fully rifled arms are much heavier. H&H claimed that its Paradox (Fosbery's original patent) would give the same accuracy as an Express Rifle at 100 yards.
Regards, Tim

Hey Tim

Don't you have a Coggie Cosmos?

I also agree with Marrakai regarding slugs. I think that the problem with my groups is compounded by the Brenneke with the attached basewad regarding the transonic thing. (there is visible tipping at 100yds that isn't there at 50.) Have to try the conicals to test that theory out

Tom

Tom,

Yes, I've a Coggie Cosmos and I'm embarrassed to say that I'm in a trough because, despite some major efforts to regulate, I cannot get both barrels to shoot together.

Velocity is in the vicinity of supersonic and, given the supermagnum experiences plus what I understand of Ross Seyfried's work with the Fauneta (20 bore Westley Richards), I wouldn't worry about that question.

Round ball did our ancestors well. But, choke rifled guns are a major improvement at the distances of hunting (as opposed to sniping).

Luck in your efforts!
Regards, Tim