Round Bottom Rifling?

Anyone have any experience with round bottom rifling in a muzzleloader barrel? Reason I ask is I am having TVM build be a rifle and for $25 more I can get round bottom rifling vs square. The barrel is a Rice 42” A weight swamped barrel of .40 caliber.

I told Melanie (TVM’s order person) to go ahead and get the round bottom rifled barrel. I did some cursory research and it appears the round bottom is easier/quicker to clean and handles fouling better for more shots between swipes (even though I normally swipe between shots). And some say they make ramming easier. Hey all sounds good for me.

As to accuracy I’m not going to do bench contests. mostly casual target shooting and plinking, some squirrel hunting, and maybe some woods walk type events. So it’s going to be more of an offhand toting type woods gun, not a dedicated target bench gun.

Did I make a good choice? Am I a fool, should I ask for square bottom rifling? Or for my usage would round be better? Also I plan to come the muzzle so I won’t need to carry a starter and I hear the old timers never used a starter so it’s more period.

Thoughts?

Both will give you good accuracy, and both are capable of about the same. With square rifling, the patch will have a better tendency to grab the rifling, so may give you a better range of accurate loads than the RB will, or give you acceptable accuracy at a lesser powder charge than it takes to get it from RB rifling. With a 40, you're probably not talking about charges greater than 70 gr. very often, so recoil at the higher charge weights won't be an issue.

Why would round groove rifling not hold a patch as well as square? Round groove rifling still has the same square land corners to grip the patch it's just the bottom of the groove is round with no corners to catch fouling.
I think it a capitol idea personally and can see no down side at this point although I don't personally own one with round grooving. I haven't had the opportunity to test for accuracy but I can see no physical reason it would not be just as accurate as any other style.

Smokey Plainsman said:

Also I plan to come the muzzle so I won’t need to carry a starter and I hear the old timers never used a starter so it’s more period.

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Earliest reference to a short starter for patched round ball is 1780s in a German text (short starters and mallets were used early on for starting oversized, unpatched balls). Earliest American reference is from the first decade of the 19th century, in a militia drill manual from New England, IIRC.

By the late flint and percussion eras a short starter is ok, I think. I wouldn't use one with a Hawken, but for an Eastern percussion rifle they'd be fine, I think.

The "they didn't use short starters" meme is in reference to the 18th century frontier and maybe the 19th century Fur Trade Era out west. Eastern squirrel hunters are different story.

Part of the round bottom rifling concern is that the round bottomed rifling is deeper so a much thicker patch is required to seal the bore at the expense of making it harder to load. The deeper rifling "may" allow gas to escape on firing and may lead to burning and tearing of the patch.

Some folks just love round bottom rifling and others just don't. My Derringer rifle and the 1803 Harper's Ferry rifle have round bottom rifling and shoot quite fine. You just need to find the right load for your rifle.

Here is the simple answer... BOTH will shoot better than you or I ever will.

That said I personally could give two turds less if one is more "accurate " than the other. Personally believe most forget a highly machined barrel will shoot far more accurately than a human ever will.

I have a SMR coming with round bottom rifling, my justification is easier to clean! :thumbsup:

My .54 has round-bottom rifling. It shoots just as well dirty as it does clean. I can put 20 shots through it without wiping.

Since you are going to have a .40 the round-bottom rifling is probably a smart choice. The smaller calibers get dirty fast so you may be able to avoid some of the cleaning between shots.

What patch lube do you use MK?

I think the lube used has a lot to do with how many shots one can fire without wiping, as well as humidity . :idunno:

I have the round bottom rifling in a L.C. Rice (0.54 swamped 42").

IMHO it is more forgiving of fouling. I only spit wipe after five downrange, sometimes ten, and cleans up easier at the end of the day.

Sounds good, fellas!

Seems from my research the difference in accuracy is so minor as to be moot, if any. Many say the gun is easier to clean at days end, gets more shots between wipes (I’ll probably wipe between shots anyway but will experiment with not doing so, I’d like to not have to carry so many shooting patches in my pouch) and I am reading that it’s easier to load, not harder. Seems finding the right load is critical but when is it not? Have also heard going up a ball size such as using .395s instead of .390s seems to have worked well for some,

My .54 has radius bottom rifling as well only it’s a Colerain barrel.

I’ve been playing around with Hornadys One Shot as a patch lube.

I basically per cut / punch my patches to size , then place a stack of them in a cap tin with a couple of good sprays of one shot on them .

I let them sit over night then there ready for use, damp but not wet.

I fired 30 shots in a range session without wiping the first time.

One shot is sold as a cleaner / protectant.

My findings is it works good as a cleaner, but I’m not impressed with its protection factor.

I’ll stick with Barricade for that.

So far I like the results as a patch lube, I’m able to clean up after a range session a lot easier than when shooting EVOO or Spit Patches. :idunno:

Very cool, does accuracy seem to drop off as more shots are fired?

Have a number of round bottom rifling barrels. Once you figure out the correct patch material I believe they are outstanding. Below is a photo of a Hoyt 58 caliber, radius bottom, 1-60 barrel. It is a real champ when using denim that compressed measures in the .016 range (.030 not compressed). I use a dry lubed patch, Ballistol and water with a 1 to 8 ratio (any questions get Dutch's System). If I swab or brush will produce 5 touching shots at 50 yards. A little over 2 inches at 100 yards. If shooting at a range or a woods walk, windshield cleaner mixed with Ballistol around 7 to 1 one works pretty good with wet patches, although groups open up to 4" to 6" at 100 yards. But you can load and shoot all day without swabbing or brushing. Wouldn't suggest wet patches for hunting because of fear of fowling powder charge as it sit in the barrel for an extended time.


Would strongly recommend against coning your barrel until you have a few hundred shots through it, if at all. When hunting I use the brass butt of a knife the old man made for me some 50 years ago to start the ball. Believe Brownbear has made similar recommendations. My first load is at the truck, cabin or where ever with a short starter, but in the field when hunting use the brass butt of the knife handle to start the load before trimming the patch. Practical as one less thing to carry (no short starter) plus the knife is one of my prize possessions that has been around the world with me. Feels good to use it. Just polished it up and put a coat of Johnson's Paste Wax on it in preparation for the coming hunting season. Rock on.

yes, you made a good choice with the round bottom rifling.

I would hold off on the cone until you have several hundred (275 to 325) shots at least through the barrel, then decide. (It's really hard to un- cone a barrel, you know).

some folks swear by it, and some swear at it.

your Rice barrel will shoot straighter than most of us can hold.

good luck with your project, and

Make Good Smoke!

Is the step in the left corner of each groove on purpose or a messed up rifling cutter?

About 15 years ago I built a rifle with a Rice B profile 40 caliber barrel with round bottom rifling. The first day it fouled so bad I could only shoot a couple of shots before I needed to clean. I started lubing my patches with LeHigh Valley patch lube and that stopped my fouling problems in it's tracks. I could shoot as many shots as I wanted with no loss of accuracy. Now that a few thousands round balls have been shot through this barrel those old fouling problems are long gone.
You have to learn your rifle as they are all different.
LeHigh Valley is still my favorite lube for both my .40 and .54 (Colrane round bottom) but I don't use it for a hunting lube as it drys out, and can cause a rust ring in your barrel and I've had patches catch fire after drying out. So it's a practice or match lube only for me.
I don't like swabbing between shots because you can push fouling down and cover your touch hole from the inside. Back in the old days we called this a "Clinker".
My barrels shoot well with a thin patch as long as it's not too large a powder charge at which time the patch will come apart. So I only use the thin patch with light loads and save the thicker patch for my hunting loads.
I'm pushing 66 and my eyesight isn't nearly what it used to be but I can still shoot fairly well with those round bottom barrels, I can only imagine what a young man with good eyes could do. I don't consider accuracy to be a problem at all.
I like round bottom barrels.
Tip about shooting 10 shot groups... after the first few shots your aiming point is shot out and it becomes much more difficult to find the original point of aim and the group spreads. At least for me.

The round bottom rifling you get from Rice will serve better than square bottom for most uses. Some round bottom rifling has wide grooves and narrow lands like the Hoyt Rifling shown above. Some round bottom rifling has narrow grooves and is not as good. The problem is that the round bottom rifling cut by most barrel makers is to small in the radius cut. Instead of being smaller than the radius of the bore, the radius of the cutter should be at least twice as large as the bore radius. The effect is that the cutter digs in on the sides next to the lands before it hits in the middle. You get round bottom rifling that is deeper along the lands and shallower in the middle A thinner patch can be used, it still grips the lands exceedingly well. It was this type of rifling that H&H barrels used. A NOS H&H barrel brought over 500 on ebay about two years ago. I used one of their barrels for light bench shooting for many years. Despite those days when all the cosmic forces aligned and my groups were nearly perfect, I was unfortunately never as good as the barrel was. Their barrels also had a choke at the muzzle. Coning such a barrel would completely destroy the reason to have the choke.

Smokey Plainsman said:

Very cool, does accuracy seem to drop off as more shots are fired?

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Nope it didn’t drop off that I could tell.

As a matter of fact it seemed to improve my groups the longer I shot.

I was shooting 70 grns of fffg Goex.

The only thing I have to do is keep the pan,flint and frizzen wiped and if I notice any gunk in the touch hole I run a pick in it.

I fired 30 shots with no wiping the bore and the 30 th one loaded as easy as the 2nd one.

When ready to clean I use a breech plug scraper first followed by a bronze or nylon brush( whichever I have handy) to loosen the fouling along the grooves.

Then I start running patches sprayed with One Shot, I use both sides of the patch while cleaning.

Normally 7 to 10 patches and your clean ready for the Barricade .

I always remove the lock and throughly clean it, but I do not always completely disassemble the lock internals every time , it really depends on how dirty it is.

It gets a shot of Barricade on the back side / internals , then the outside of my gun gets wiped down and put away.

I’ve had guns stored for 7 to 8 years with Barricade on them without any issues.

I use denatured alcohol to swab the bore prior to the next shooting session.

My guns were in a safe with a dehumidifier rod in place , but I’m a firm believer in Barricade as a rust preventative .

Good Luck in your flint adventure :thumbsup:

M.D. said:

Is the step in the left corner of each groove on purpose or a messed up rifling cutter?

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Shape of the cutter when the barrel was rifled. It’s about .001” and only visible with perfect light and/or magnification (like in my photograph) and doesn’t impact performance in any way. This is ”˜hand’ cut rifling. Have seen period barrels with more pronounced ”˜fingerprints’.

M.D. said:

Is the step in the left corner of each groove on purpose or a messed up rifling cutter?

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Just looks like a photo anomaly to me.