Round bottom grooves vs flat

[Iktomi]

  I am getting ready to place an order for a Kibler Colonial rifle in .58. There is an option for round bottom rifling grooves on the Rice barrel. What are the advantages and is it money well spent to get them?

[EC121]

Round bottom grooves are deeper and require a thicker patch(and maybe a smaller ball for easier loading) to seal, but they are supposed to be easier to clean.  I can't tell the difference in the cleaning.   As far as accuracy, either one will work to impart spin on the ball.   Don't get too caught up in the rifling.   Many a match has been won by a barrel with .008" rifling. 

[rich pierce]

Long time great match shooters in my club stay traditional with square grooves. Not sure they’ve done statistics but squardgrooves give them results so why change?

[Iktomi]

My GPR with square bottom grooves is easy enough to clean and is quite accurate. Thanks for the input, I'd rather spend money where it can do some actual good

[Scota4570]

I don't like deep rifling round or square.  IT makes getting a good seal difficult.  By the time the patch is thick enough to get enough compression in the grooves the lands are so tight that loading is difficult.  I have a 45 cal with RB rifling that requires denim patches to get decent accuracy.  Loading requires a starter and a wood ram rod is sketchy.

Our local club champ shoots a TC with it's shallow rifling.  I have made very accurate ML barrels out of 45-70 blanks.  I don't think deep or RB rifling is needed or even desirable.   

[Iktomi]

I don't like deep rifling round or square.  IT makes getting a good seal difficult.  By the time the patch is thick enough to get enough compression in the grooves the lands are so tight that loading is difficult.  I have a 45 cal with RB rifling that requires denim patches to get decent accuracy.  Loading requires a starter and a wood ram rod is sketchy.

Our local club champ shoots a TC with it's shallow rifling.  I have made very accurate ML barrels out of 45-70 blanks.  I don't think deep or RB rifling is needed or even desirable.

 To be honest, I don't know if the RB rifling on this particular setup is deeper than the square or not, but your point is taken, and makes sense to me.

[Mike Brooks]

I have never noticed any difference.

[Scota4570]

I just measured the barrel I shoot most.  It is a .450 bore and .480 groove.  That makes 0.015 deep per groove.  The lands are very wide and the grooves are narrow semicircles. I don't care for it.

I think that is just opposite of what would work best.  I would want the grooves to be wide and flat with radiused corners,  like Pope used to do.  His grooves were very wide with tiny little lands.  The grooves were in the form or a polygon the center of which was bore diameter.  To me that would be ideal.  Huge purchase on the patch/ball but the least amount of windage to take up with the patch.  Unfortunately I know of nobody who makes such a barrel.   

[D. Taylor Sapergia]

A barrel with wide lands and narrow grooves is more difficult to load than one with narrow lands and wide grooves.
Theoretically, radiused grooves without corners are easier to clean than barrels with sharp corners at land-groove.  But both are easy to clean.
All barrels with rifling and a uniform bore are accurate...quote from Don Getz, RIP.

[okawbow]

My rifles with deep, round bottom grooves shoot accurately with almost any powder load, and will shoot all day without wiping between shots, if I use a thick patch and the correct size ball. Cleans up easily also.

That said, I use square bottom grooves in my match target rifles. I wipe between shots with these, so easy loading is no problem.

[hanshi]

I own and like both.  An rb barrel may be just a little faster to clean or it sometimes seems so.  Round grooves are probably deeper than they need to be, but I've encountered no problems using thicker patches and the wood rod.  Radius grooves work well for hunting as well as for an all-around rifle.  However, if I were to have a rifle built for targets and/or maximum accuracy, it would be a straight barrel with square grooves.

[Darkhorse]

I think the round bottom barrels are easier to clean. It didn't seem so for several years though, then I changed my process using a toothpick in the TH and the difference was apparent right away.
I can tell no difference in the accuracy between a square bottom and round bottom as long as you take your time to work up a good load.

[Daryl]

Given a choice BEFORE the rifle is built, I will ALWAYS choose .010" to .012" deep square bottomed rifling.
I have a barrel with quite deep rounded rifling and it is OK, but I prefer square.  I do not find it easier to clean than any of my square rifling barrels. This
may be due to narrower grooves than lands, which is the wrong way to do it, as Taylor notes. It is difficult to get a good seal due to the rifling design, and
thus does pick up a bit of fouling. Loading remains easy all day, though, no wiping. Accuracy also remains consistent.

Loading is much easier with a tight combination in square rifling as described above, than to get a good seal in deep, rounded grooves,
especially in smaller (under 54) calibres that run higher pressures.

For a .58, I would most certainly still stay with square, in .012" or so rifling depth.  a .575" ball mould and 10 ounce denim (.022") along with 85gr. to 110gr. of 2F will
shoot most pleasantly and give excellent accuracy as well. This patch/ball-size (.005" under) 'recipe' works in all calibres we've tested, from .32 to .69.

[Scota4570]

For my purposes cleaning is not an issue. My club demands that the bore must be swabbed between shots.  I just want the easiest loading most accurate combo. 

[stubshaft]

I ordered the Colonial in .58 with round rifling.  I do not care to squeeze out the utmost in accuracy as I have many other rifles to shoot and kill paper with.  I understand and agree with many of the viewpoints offered here. This will be my first round groove barrel build.  Why, because I like the looks of it.  Plain and simple.  I will probably use this rifle for general woods walks and plinking.  If I take it hunting my shots WILL be under 50 yds. as I am primarily a bowhunter and usually do not shoot beyond 20 yds. so accuracy is not a problem or concern.

[Mike Brooks]

For my purposes cleaning is not an issue. My club demands that the bore must be swabbed between shots. I just want the easiest loading most accurate combo.

You gotta be kidding........ The goobermint run your club?

[Iktomi]

 Thanks gents for your input. It seems there is no real advantage to RB groove rifling. I think I will apply the cash towards upgraded stock wood.

I ordered the Colonial in .58 with round rifling.  I do not care to squeeze out the utmost in accuracy as I have many other rifles to shoot and kill paper with.  I understand and agree with many of the viewpoints offered here. This will be my first round groove barrel build.  Why, because I like the looks of it.  Plain and simple.  I will probably use this rifle for general woods walks and plinking.  If I take it hunting my shots WILL be under 50 yds. as I am primarily a bowhunter and usually do not shoot beyond 20 yds. so accuracy is not a problem or concern.

  I am primarily a bowhunter as well, but I will take whatever bit of accuracy I can get, be it archery or rifles. Compared to modern suppository rifles, BP hunting is still a fairly up close game, but having the ability to drive tacks with whatever the weapon of choice isn't a bad thing. I agree that round bottom grooves look cool though

[stubshaft]

I misstated that last sentence.  What I should have said is that "within 20 yards the difference in accuracy is not a concern.  I do not own a rifle that will not group less than an inch at 20 yds."

Joe

[Frank]

For my purposes cleaning is not an issue. My club demands that the bore must be swabbed between shots. I just want the easiest loading most accurate combo.

You gotta be kidding........ The goobermint run your club?

Wow, Time to find another club.

[Brian Jordan]

My club demands that the bore must be swabbed between shots.

I have never heard of anything so ridiculous.

[wattlebuster]

I cant tell a nickles bit of difference in square or round and I have both. All my shooting practice is for hunting so most my shooting is offhand. Only bench shooting my guns see is when trying to find the load it likes an then set the sights. As far as cleaning goes one cleans as easy as the other

[Iktomi]

My club demands that the bore must be swabbed between shots.

I have never heard of anything so ridiculous.

 I wonder if the range masters are called "swabbies"?

[Hungry Horse]

If I had my choice of any rifling style, twist, and depth, it would be (depending on caliber of course) slow, not much over twelve thousandths deep, wide square bottomed grooves with narrow lands.
 I shot an old Hawken .54 cal. Fullstock with a Bill Large barrel in this configuration, and it was deadly accurate. With the right shooter, nobody in our area could outshoot this rifle, including some with Large’s  standard rifling.

  Hungry Horse

[Daryl]

Years ago, I had a rebound-effect from the shallow buttoned barrels TC was sending out in the 60's and 70's.
Friend Tommy's TC had 1 1/2 thousandths deep rifling, while Taylor's TC was 2 1/2 thous. Mine was a full 4 thou, that's .004".
Their rifles shot the slug best as the rifling was just a bit shallow for hunting loads with patched balls, although Taylor shot
a bunch of deer with his, using round balls.  My rebound and loud voice, I expect might have been some part of the reason
that friend Hugh started off with really deep rifling - the first one was about .025" deep.  I tested it and had difficulty getting
it to shoot. Of course, I was using my standard .495" ball and .022" denim patch that worked well in TC's barrel, albeit it was
tight. I could not seal the deep grooves as I needed a .490" ball and .030" or so patch.  That would likely have worked quite
well.  My bad for not trying that.
What I really wanted, was a barrel with rounded .012" deep rifling and slow twist. Hugh was on his way making .025" to .035"
deep rifling and I could find no one to make me what I thought might be the best overall - about 75 to 90" twist, rounded bottoms
and .012" deep.
I figured it would load easily, shoot well with 'good' stiff hunting loads and clean up like a dream.

[Marcruger]

" This will be my first round groove barrel build.  Why, because I like the looks of it.  Plain and simple. "

Wow, good luck with that.  In my experience, the barrel is the most important part of the gun (the lock second).  Picking by the groove appearance seems a strange road to travel.  I hope you don't add an Italian lock because you like the way it looks. 

I am not a fan of round-bottom grooves after trying one.  It was nearly impossible to get to seal.  The blow-by ruined consistent velocity, and accuracy was mediocre.  Clean up was bad.  I switched back to flat-bottom grooves.  No problems at all now.  Flat bottom rifling all the way for me.

Best of luck with this project.   Marc