Round Bottom V Square Bottom Rifling

[rjpalmer]

What are the pros and cons of round bottom v square bottom rifling? I can't seem to find any information about the topic. I wasn't even aware that round bottom rifling even existed.

[Daryl]

Here;s a full page of talk on the subject:

https://americanlongrifles.org/forum/index.php?topic=38975.msg377972#msg377972

many like it, many don't

suffice to say,
If it was better, accuracy wise, the serious match shooters, plan, chunk, bench rest would use it. They don't.

[Daryl]

Some with rounded rifling, which generally is .016" deep or deeper, along with one barrel with square rifling that is .028" deep.
(that one isn't recommended either)







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[rjpalmer]

Thanks for the information. I know I had read an article about round v square bottom rifling some time in the past, but couldn’t remember the particulars. I guess I ‘ll stick to square bottom rifling and avoid any future headaches. I’ m just a casual shooter these days, but have my eye on one of Jim Kibler’s kits and noted he offers round bottom and square bottom rifling. Every time someone posts a picture of one of Jim’s rifles it really  sparks my interest.

[stuart cee dub]

 I've built rifles with both round and square bottom rifling.
I haven't been able to definitively tell which is more accurate.There are too many other variables like lock time trigger pull stock fit that come into play .

That being said all the recent full stock, flint ,pinned barrel rifles I have built all have round bottom rifling.
The reason is they are ,with the cleaning methods I use, which includes leaving the barrel in the stock ,so much faster and easier to clean that I won't use anything else .

My favorite half stock percussion gun is highly accurate and has square rifling.
It's the devil to clean ,the grooves are deep and crud seems to accumulate in the corners after a day's match . The barrel is keyed and I pull it every time to give it the bucket treatment .It takes me 45 minutes to clean it to my satisfaction .The flinters take about 15 minutes and a third the number of patches .

As such ...If I were ordering one Mr Kibler's kits in flint and using a pinned barrel I would order the round groove simply because of the ease of cleaning .Shooting off hand if the square groove  barrel were even slightly more accurate I would never be able to tell.Things like lock time and trigger pull likely have more to do with practical accuracy that rifling style .

[Marcruger]

If you look at the national BP meets, the barrels are almost always flat bottom.

I will only use flat bottom unless it is a Colerain, as they have shallow round grooves. 

Deep round grooves are miserable to try to seal with patching.

Flat bottom rifling is easier to get to seal.

If round bottom rifling is deep, and you cannot get a good seal, then the bore will foul badly, making cleanup harder.

I honestly believe people buy round bottom due mainly to looks, not performance.

I hope this helps.  God bless, Marc

[Eric Krewson]

I am a fan of flat bottom even though I jumped on the round bottom train when I made my first gun. My square bottom rifled guns shoot just about any load well, my round bottom guns shoot well but it took awhile to figure out what they liked.

[axelp]

I have a round bottom rifled gun and a square rifled gun and cannot honestly tell the difference in cleaning. They both take about the same amount of time as far as I can tell. But I have never actually timed it. Cleaning time has other variables that make it hard to get a good measure--- temp and humidity and of course the number of rounds thru the barrel, and time from when you shoot to when you clean...

[smylee grouch]

If someone has a hard time cleaning their rifles, round or square maybe they should review their load and loading . Try a different patch and or lube. I get my barrels clean with water and two-three patches and then dry with two-three. About 5-10 min.  I know from my own shooting and trying to compete along side of many national champs that the square cuts are first choice.

[bama]

Unless you are an exceptional shooter I don't think you can tell a difference as far as accuracy goes.

If you are a die hard paper puncher then I think the square bottom rifling may be better.

If you are the average shooter you won't be able to tell the difference. I shoot both and both will shoot as accurate as I can hold them. I have found that it takes me less time to clean the round bottom rifling than the square but not by much. So then for me it comes down to preference and I will tell you that I will take a well manufactured barrel by any of our brother barrel makers whenever I have a need for a barrel regardless of the rifling. I have full confidence that when I finish a rifle that uses one of the current barrel makers barrels it will perform and do it well, we have some of the best barrel makers in the world in this sport.

[Scota4570]

I used and later scrapped a 45 cal RB.  It never shot accurately enough to satisfy me. 

The grooves and lands were equal width.  The grooves were 0.016" deep in the center.  A patch thick enough to seal the grooves was so tight in the lands that loading was very difficult.  I think the issue was not RB per say but the average groove width was too narrow and the grooves were too deep. 

I think RB would be fine if RB was not so deep and the lands were narrow.  0.016" deep appears to be OK in larger bores than my 45.  To my sensibilities Pope or Henry style rifling would be great with a patched ball. Someday I hope to get a barrel made to test my ideas. 

[Daryl]

Scota - I tried to get Hugh to cut some with slow twists and shallow round btm. rifling back in the late 70's
as I'd switched my thinking from super deep to shallower rifling, as it was difficult to seal .024" sample I had
for testing. I could not get it to shoot to my satisfaction. It was a beautiful bore to look at, but I failed to seal
it with .495" balls and the thickest denim I could find at .022" compressed.
My Bauska barrels with square bottomed rifling shot much better.

[elkhorne]

Akin to this discussion of round vs square rifling, Stuart mentioned cleaning without removing his barrel. A while back, I came upon a professional builders website that he gave an excellent demonstration of cleaning without removing the barrel. Has anyone else seen this demonstration or remember what the website was? It would help a lot of us. Thanks.
elkhorne

[Scota4570]

Scota - I tried to get Hugh to cut some with slow twists and shallow round btm. rifling back in the late 70's
as I'd switched my thinking from super deep to shallower rifling, as it was difficult to seal .024" sample I had
for testing. I could not get it to shoot to my satisfaction. It was a beautiful bore to look at, but I failed to seal
it with .495" balls and the thickest denim I could find at .022" compressed.
My Bauska barrels with square bottomed rifling shot much better.

The thing that intrigues me  about Pope rifling is that the difference between land and groove diameters is the absolute minimum.  There are eight L/G's.  The grooves are wide and flat.  The center of the groove just cleans up the bore diameter.  There are small lands in corners of the grooves.  IT is an octagonal polygon bore with small lands in corners of the octagon shape.  Each groove corner is radiused. 

I can not imagine a better set up for a patched ball.  The difference between L and G diameters is the smallest possible.   And, yet the octagon shape with lands give massive purchase on the patched ball.  Pope designed it for muzzle loaded bullets.  The design considerations are the same for our use.  Ease of loading, best gas seal and minimal projectile deformation are all optimized.   

[Bob Roller]

Pope rifling appears to be an 8 groove Alex Henry.Bill Large made some round ball barrels using
that system and was told by "X-Spurts" it can NOT work with a patched round ball.I tested it at
100 measured yards on Bill's range and those folks were WRONG x 10. A ragged one hole group with
5 shots out of the first 54 caliber barrel was what it was shot with.Helmut Mohr in Germany tells
me of the Rice barrels he uses on his schuetzen rifles in 9.3MM with bullets and he says it is as good
as a 22 caliber target rifle.The 9.3MM is a .366 and uses the Pope system.
   I don't know how many of these larger bore round ball barrels Bill Large made like this but anyone
that has on now has a treasure. Bill made a rifle with ONE breech plug that we used on any test barrel
and the inlet in the stock was the same as all of the test barrels. I THINK it was a 1 and 1/16" straight
and a tang sight I made and a standard Lyman 17A.One more thing.The ball was a .535 and loaded
tight with striped pillow cloth and 80 grains of DuPont 3FG.

Bob Roller

[Marcruger]

"I have a round bottom rifled gun and a square rifled gun and cannot honestly tell the difference in cleaning. They both take about the same amount of time as far as I can tell. But I have never actually timed it. Cleaning time has other variables that make it hard to get a good measure--- temp and humidity and of course the number of rounds thru the barrel, and time from when you shoot to when you clean..."

Wise words Ken.  I agree.  The humidity here in the south can introduce all sorts of variables.  This includes powder grunge in the pan.

My point was that (in my experience) if you cannot get a barrel to seal, then blow-by tends to bake grunge into the bore which is harder to clean up.  The deep round-groove barrel I had was a beast to clean for that very reason.  My friend's Colerains with shallow round bottom grooves shoot accurately and clean easy. 

I hope this helps.   God Bless,   Marc

[stuart cee dub]

 Regarding groove depth on the round groove barrels I hadn't considered that .
The three round bottom rifles I have they use respectively a Paris , a Rice and a Colerain barrel .At least with those barrels I've had great luck .
The dirtiest barrel is an Orion 1-48 square groove in 45 cal , The grooves are square and deep and it will shred anything less than cotton canvas patching.And it really wont shoot well with 3 fg .It's a pig to clean and a great shooter .

 So perhaps groove depth round or square are problematic to clean if they are too deep period .

Elkhorne ,regarding cleaning with the barrel in ,I never saw a video .

One of the guys I shoot with Pevine always cleans his rifles barrel in  right there on the range and I simply learned by watching .Part of his secret is a very good quality spray bottle with BP solvent and a toothpick to plug the touchhole.
The spray bottle turned to stream directs the solvent into the bore when placed in the muzzle . The lock gets pulled every time sprayed and scrubbed . I think this really works better with flinters .Percussion has too many nooks and crannies if you have a drum set up.

I won't build a percussion gun nowadays without wedges and as a half stock only . A personal prejudice .
 

[Marcruger]

Hello Stuart,

I think you are right about the depth of rifling. I guess any rifling that is too deep is a bear to seal up with patching and rough to clean.  I am sure there are exceptions, like always. 

The friend who taught me to shoot brings home medals from Friendships quite often.  He is ultra competitive.  He hauls several guns to each meet, each set up for a different match.  He's the one who told me about the rifling depth.  His opinion is anything over .012" deep is a step in the wrong direction.  He normally shoots only Green Mountain flat bottom barrels, but his two flinters are Colerains, with shallow round-bottom rifling.  I cannot fault his results.  Since a .011-.012 depth seems to shoot great, I am personally not sure why makers opt for deeper rifling.  Looks?  The fight with deep rifling is to get thick patching driven down into the deep grooves by a fat ball, and still be able to get the load started and  down the bore. 

I too always clean my guns 100% at the range.  I have a toothpick and a small funnel.  I plug the touch hole, and fill her up with lukewarm water and let it sit. I wrap a patch around the toothpick, and use the frizzen to trap the toothpick in place.  That patch is to catch any leak.  I also wrap a rag around the gun at the tang to prevent any leak from leaving a streak on my buttstock wood.  Yes, I clean my lock at the range too.    The only thing I do at home is to run a few oiled patches down the bore the next day before storage. 

This is what works for me.  Others obviously have differing ideas. 

God Bless,  Marc

[JBJ]

Years ago, I built a rifle using a Douglas .40 standard grade barrel. Breeched with the runout down, it shot virtually one-hole groups at 50 yards with 60 grains of DuPont 3F, spit patch double thick cotton flannel, and a .402 roundball. Wish I had the 30-yr-old eyes, the rifle, and that mold back. Does anyone recall what rifling depth Douglas used on their 1x48 twist barrels? I want to say on the order of .010 or .012 square bottom but ?? IMO, we could do a lot worse than copying the old Douglas barrel rifling or the Pope style previously mentioned. I have a Rice barreled rifle in .32 with round bottom rifling. I'll say it is OK and leave it at that. Of course the eyes are now 77. Oh, well.
J.B.

[Daryl]

This is a good style, if slow, for a large bore rifle using pure or hard lead. I would love to have just such a barrel on my .69
except the one pictured is a little light in weight.

[smylee grouch]

Daryl, are the cuts on that "Renner" barrel flat on the bottom?

[Daryl]

They appear to have the radius of the bore, smylee, having equal depth all the way around.

[smylee grouch]

Ok, thanks for the info. I too like the looks of that riffling, but also think it might be a bit light weight.