Author Topic: Let's Compare Rifling Types  (Read 15710 times)

Leatherbelly

  • Guest
Let's Compare Rifling Types
« on: March 11, 2009, 03:58:43 AM »
 Gent's,
   I would like to learn the ins and outs,pros and cons of round bottom and flat bottomed grooves in rifles. Let's throw in: a)with swamped,b) with straight. I just need to know! I'm a smoothbore shooter,for Pete's sake! ;D ;D
  Don't be shy,wade in here.
added: Is one more accurate then another?
« Last Edit: March 11, 2009, 04:15:23 PM by Leatherbelly »

fredj

  • Guest
Re: Let's Compare Rifling Types
« Reply #1 on: March 11, 2009, 08:47:50 AM »


I've never owned a rifle with round bottomed rifling, but from what I've read and or been told, the round bottomed rifles are somewhat less fouling sensitive, easier loading and a scoshe less on the guilded edge accuracy capability, some of that reputation likely based on the fact that round bottomed rifled barrels probably could use thicker patching than many owners are typically using.

  In my experience I've found that just about any basically sound barrel is capable of being far more accurate that just about any owner is capable of exploiting, it just comes down to just how patient and methodical the owner is in working up his loads.
the really fine barrels generally being easier to get the desired accuracy out of it.

  As far as swamped vs. straight octagon profiles is almost entirely a function of aesthetics and balance.

FJ

Offline Roger Fisher

  • Hero Member
  • *****
  • Posts: 6805
Re: Let's Compare Rifling Types
« Reply #2 on: March 11, 2009, 04:54:24 PM »


I've never owned a rifle with round bottomed rifling, but from what I've read and or been told, the round bottomed rifles are somewhat less fouling sensitive, easier loading and a scoshe less on the guilded edge accuracy capability, some of that reputation likely based on the fact that round bottomed rifled barrels probably could use thicker patching than many owners are typically using.

  In my experience I've found that just about any basically sound barrel is capable of being far more accurate that just about any owner is capable of exploiting, it just comes down to just how patient and methodical the owner is in working up his loads.
the really fine barrels generally being easier to get the desired accuracy out of it.

  As far as swamped vs. straight octagon profiles is almost entirely a function of aesthetics and balance.

FJ
And barrel whip!  (Harmonics)
« Last Edit: March 11, 2009, 04:55:00 PM by Roger Fisher »

Daryl

  • Guest
Re: Let's Compare Rifling Types
« Reply #3 on: March 11, 2009, 06:47:34 PM »
  In a fairly accurate, Rice round bottomed rifled gun, I've 'witnessed' the normal smaller ball, ie: .010" 'under' with a .022" denim patch being fairly accurate. When suggesting the owner try a .005" 'under' ball, there was an immediate improvement in accuracy.  The rifling of this barrel is about .016" deep.  We should do the math - .500" bore, + .032" for rifling = .532" to the bottom of the grooves.  A .490" ball (.010"-under) + 2 wraps of .022" = .534", only .002" compression total and .001" per side.  The .495" ball + .044" patch = .539" for .007 compression, or .0035" compression per side - a tighter fit and instantly better accuracy, even with the light squib load of 80gr. 2f for 1,400fps.  In this barrel, 3F would probably give even better accuracy at 80gr. as the velocity would be more in tune with the rifling twist, which is slow. We tried a .509" ball with a .020" patch and it loaded fairly easily, although took more care in loading than the smaller ball.  It 'should' prove to be more accurate showing more testing is in order.

To date, I've only had one round bottomed rifled barrel- and that, a test.  I was unable to achieve the accuracy I've come to expect from my other barrels.  This test wasn't quite fair, as the barrel was a test as I said, a 'first' attempt at deep rifling at .025" deep. I didn't like it.  Rice barrels with .016" rifling seem to shoot just fine, given a 'proper' tight load, just as a square rifled barrel gives good accuracy.  One I still have, a .45, has .028" square rifling - yet it shot well. It also needed a very smooth radius'd crown to load. The only way to get to the bottom of the grooves was to use a ball .009" over bore diameter and a .022" denim patch. With this, it shot exceptionally well and was fairly easy to load.  The same scenario in the .seep .50 failed to elicit anything that could be called descent accuracy. Why, I don't know - it should have shot well.

Another deep grooved barrel of my acquaintance is .75 cal. and about .025" deep grooves. With only 100gr. of powder, it shoots fairly well at close range - to 50yards - and for a  .75, that is close range indeed.  At 100 yards and beyond, it needs a lot more powder which creates fouling problems.  Deep rifling in large bores is neither wanted nor necessary.  With 70" to 80" of twist, the rifling needs only be .006" to .008" at most.  Today, most barrel makers over-cut rifling.  The result is a requirement for heavier than necessary patches to reach the depth of the rifling.  Shallower rifling would be somewhat faster to cut, easier to load and cleaner shooting.

So far, the square rifling of .010" to .012" depth works well even at extreme velocities attainable in small calibres of .38 to 40 with what seems to be a fast 48' twist. Why is it that barrel makers seem to think they need to make even deeper grooves in larger, slower moving calibres with even slower twists?  The higher the speed, the higher the pressure and the more 'hold' the ball needs - if a .40 can produce well over 2,000 fps in a 48" twist with only .010" rifling, why do barrel makers still cut grooves to .016" or deeper, for slower moving balls in slower twists yet?

I think deep rifling is a wrong move for a slow moving round ball twist. They show that don't need ideep rifling. I'd like to test a .45 or .50 with 60" to 70" twist, round rifling and only .010" deep. That one I know, will shoot & shoot cleanly and clean easily.  Easy cleaning is a trait of round bottom grooves. I think we need to readdress this rifling depth issue.

Due to the rounded bottoms and sides of round bottomed rifling, more depth is needed than with square rifling, but the barrel makers are overdoing this.

Perhaps everyone is still in recoil from the buttoned barrels of the past, with their .002" to .004" deep rifling.  I know I did, but got over excessive depth fairly quickly.  Some depth we need, like perhaps .008" for square and .012" for round, but .016" through .025" isn't needed.

One other aspect of rifling is shape; ie: width of lands compared to groove width.  Narrow lands and wide grooves loads easier, cleans easier and shoots accurately.  Check out a Goodioen match barrel - THAT is a good land to groove ratio - about 2:1 to 2.5:1 to one, groove to land.  Couple wide grooves and narrow lands with an oversize ball and .020" patch and loading is as easy as a normal .005" under and .022" patch.

Roger - As far as swamped vs straight vs tapered octagonal - I've only experience with straight octagonal barrels.  I do know what I've seen concerning swamped barrels; that, when Taylor is shooting any of his rifle which all have swamped barrels, you can only hope he whips some off the targets. Not likely to happen. He is a fellow who can shoot offhand to the capability of the rifle.  Those of us shooting more accurate, straight octagonal rifles (bench proved) still come up short on the trail as we (I) can't shoot to the rifle's capability - but I'm practising now, something I've not done for some years.

Offline Jerry V Lape

  • Hero Member
  • *****
  • Posts: 3019
Re: Let's Compare Rifling Types
« Reply #4 on: March 11, 2009, 08:10:27 PM »
Daryl, in paragraph 7, did you get your depth numbers right for the button rifled barrels?  I have trouble understanding that paragraph with those numbers? 

Mike R

  • Guest
Re: Let's Compare Rifling Types
« Reply #5 on: March 11, 2009, 10:05:54 PM »
I own three round groove rifled barrels [Colerain, Rice, Getz, all swamped] and a half dozen square rifled barreled guns [mostly str oct].  My most accurate rifle is an old Green River barreled .45 longrifle I built in 1978 with sq rifling.  But I am no longer a good authority on accuracy, as I once was a crack shot....but the gunmaker who made one of my .50s with a Colerain round rifled barrel uses the very same made rifle to win matches as does his son.  His load is weaker than mine and his patches thinner [same ball size].  Alot of it is the shooter, not the minutia of loads, barrel design, etc [not that that is totally unimportant].  All of my barrels [by just about every maker out there past and present] shoot better than I can hold.  I will say that round bottom grooves are a snap to clean--takes less than half the time.   

billd

  • Guest
Re: Let's Compare Rifling Types
« Reply #6 on: March 11, 2009, 10:12:18 PM »
I find round easier to clean and load. Both can shoot better than I can hold.

Bill

Candle Snuffer

  • Guest
Re: Let's Compare Rifling Types
« Reply #7 on: March 11, 2009, 11:10:19 PM »
I find round easier to clean and load. Both can shoot better than I can hold.

Bill

My findings as well, Bill.  I've only ever owned one round bottom barrel (the one Ed Rayl made for me), .40 caliber - 1 in 72 twist - ten tho. depth rifling,,, it's a shooter that seems to like just about any charge I choose to feed it, and a 65 grain charge of 3f gives amazing accuracy.

On the other side, my .45 GMB w/ 1 in 60 twist - twelve tho. depth square bottom rifling also gives very good accuracy with a 65 grain charge of 3fg...

I've found both barrels and calibers, along with their respective rifling depth's and twist's, outstanding for accuracy, easy of loading, and cleaning as well.  I would think however that one would have to give the cleaning edge to the round-bottom rifling as there is no sharp "L" corners for residue to hide in like with the square bottom.

 

northmn

  • Guest
Re: Let's Compare Rifling Types
« Reply #8 on: March 12, 2009, 02:01:24 AM »
I would suggest taht square bottomed rifling may be slightly less than sharp square so as not to cut patches.  I do not think anyone has ever proven a type of rifling to be vastly superior.  Nobody has even found an optimum twist with round ball either.  Rifling gets a ball spinning and maintains the center of gravity along a theorectical center axis.  Rifling types cannot do anything more than spin the ball.

DP

roundball

  • Guest
Re: Let's Compare Rifling Types
« Reply #9 on: March 12, 2009, 03:31:46 AM »
Gent's,
   I would like to learn the ins and outs,pros and cons of round bottom and flat bottomed grooves in rifles. Let's throw in: a)with swamped,b) with straight. I just need to know! I'm a smoothbore shooter,for Pete's sake! ;D ;D
  Don't be shy,wade in here.
added: Is one more accurate then another?

I might know later this year...I've had a GM .58cal x 1:70" square bottom grooves for a few years and its extremely accurate...doesn't seem to matter what powder charge I use...if I get the front end sort of in the direction of the target the balls just seem to find their way into the bullseye...it, and an identical .40cal GM barrel are both just scarey accurate.

I'm having a rifle built with a Rice 38" swamped D-weight .58cal barrel that has .016" round bottom grooves...Rice didn't happen to have a square bottom groove rifle in stock at the moment, but had the round bottom...I asked him what differences there might be in accuracy and he said unless I was one of the top shooters on the national circuit, I'd never be able to tell any difference.
I noticed that it cost about $50 more than the square bottom barrel.

Seems odd they'd go to all the trouble of such a unique groove design just to make it easier to load & clean...never had any trouble loading or cleaning square bottom groove barrels...but at any rate, I'm now the proud owner of a round bottom groove barrel !

Daryl

  • Guest
Re: Let's Compare Rifling Types
« Reply #10 on: March 12, 2009, 03:45:27 AM »
Daryl, in paragraph 7, did you get your depth numbers right for the button rifled barrels?  I have trouble understanding that paragraph with those numbers? 

Yes - Jerry - I got it right, however I suspect most of the TC button'd barrels were closer to .004" depth. I should have used the word 'depth' instead of deep after the .004" measurement .  The people's 'recoiling' was toward very deep rifling for round ball barrels due to the shallow button'd $#@* we were subject to in the interests of cost cutting.  I got over excessively deep rifling early on (by 1980's anyway) , but see some gun makers still cutting them excessively deep - aka- my friend's .75 cal. barrel with .024" rifling.  Sometimes you have to be inside my weird mind to understand me - sometimes even I have to ask- what DID I mean by that?

  Hall Sharron tried to deep-groove with a button back in the 70's and managed about .006" to .007" but his concrete shop used to shake like it was going to expload. I was witness to this 'earth shaping episode' in 1975.   I wasted money on a .36 cal barrel he rifled about .006".  Running a ball or tight patch down the barrel felt like running your hand over a garden rake - quickly. Vddddddddddddt.

The .002" depth of rifling was measured in a TC owned by a close friend, Taylor's was .003" and mine, lucky me, was a whole .004" depth, per side - and wonder of wonders, here we are on a bear hunt up "The Nass" valley.  Yeah-  that was a long time ago.
« Last Edit: March 12, 2009, 03:56:33 AM by Daryl »

Offline Dphariss

  • Hero Member
  • *****
  • Posts: 9741
  • Kill a Commie for your Mommy
Re: Let's Compare Rifling Types
« Reply #11 on: March 12, 2009, 05:46:42 AM »
Shallow, .008" or so wide square grooves. Shoot cleaner load easier. No contest.
Have a pair of round bottom that I don't like much but have not shot it a lot. Loads hard etc.

Dan
He who dares not offend cannot be honest. Thomas Paine

Daryl

  • Guest
Re: Let's Compare Rifling Types
« Reply #12 on: March 12, 2009, 11:24:57 PM »
Taylor's Virginia .50 with a Rice barrel loads easily with a .495" ball and .022" denim patch and does not build fouling, shot to shot.  We've even tried .509" balls with a .019" denim patch and it loaded OK too. This barrel is a round bottomed with .016" depth of rifling.  It is crowned properly.

Offline rich pierce

  • Administrator
  • Hero Member
  • *
  • Posts: 18822
Re: Let's Compare Rifling Types
« Reply #13 on: March 13, 2009, 12:42:38 AM »
I have a Getz barrel with 12 grooves and haven't built it yet, but I bet it will take a very tight ball/patch combo as the ball should deform easily to the narrower lands.
Andover, Vermont

Leatherbelly

  • Guest
Re: Let's Compare Rifling Types
« Reply #14 on: March 13, 2009, 03:47:30 AM »
  Cool pix, Daryl! Rough lookin crew!  L O L

Daryl

  • Guest
Re: Let's Compare Rifling Types
« Reply #15 on: March 13, 2009, 04:52:31 PM »
I would suggest that square bottomed rifling may be slightly less than sharp square so as not to cut patches.  I do not think anyone has ever proved a type of rifling to be vastly superior.  Nobody has even found an optimum twist with round ball either.  Rifling gets a ball spinning and maintains the center of gravity along a theoretical center axis.  Rifling types cannot do anything more than spin the ball.

DP

Along the lines of your first statement, DP - I did test a square bottomed rifled barrel having .028" rifling, grooves same width as the lands.  Due to the smooth and radiused crown, not coned, I was able to easily load the rifle with excessively large balls and thick patches- without cutting.  This was an exceptionally deeply rifled barrel, one the 'machine' didn't stop at a pre-set # of strokes and kept cutting more deeply.  Les Bauska more or less gave me this one during my visit in 1975.

I had quite a time with it to start with, as I started with .445" balls and poor accuracy, even at 25 yards.  I progressively increased the ball diameter to .451", .454" and finally .457".  The bore was .448", so I was .009" larger than the bore, using a short starter to get things started, and a 3/8" hickory rifle rod to seat them.  Recovered patches were always burnt until I hit upon the .454" ball.  Doing the math showed thinner ball/patch combinations to lack any or enough compression in the bottom of the grooves to seal the gasses behind the ball.  Any time gasses can rush past the ball, they scorch then burn the patch, while also burning and cutting the ball at the 'rush-past' spots.  With the .022" denim patches, a .457" ball of pure lead, seating a ball into the rifling then pulling it out again, revealed a slightly elongated .45 cal 'slug' - this swaging action happened in the muzzle crown.  There was no cutting of if the patch when loading, nor when putting it on the powder, nor when shooting.  Getting the seal was the important thing, and this 'type' of loading stayed my basis for developing muzzleloading rifle loads ever since.  Note the ball + patch combination comes only to .501", while the groove depth is .504".  I'm assuming, due to lead movement during the swaging process, that the grooves were actually tightly 'patched', with the .454"ball and even beter with the .457" which I eventually found to be the best.

One day at the range with this rifle, a while after I'd found a good load with it, a fellow came to me complaining he couldn't load my suggested combination of a  .495" ball with .020" patch in his TC Hawken.  His was one with the deeper, .004" rifling.  I asked him for a ball and patch, dropped in 75gr. of 2F, then set the .495" ball on top of my muzzle just to show him it was indeed a .45.  I then lubed the patch, ball sitting on it well proud of the muzzle and with one smack onmy starter, short stud on the ball, seated that over sized ball into my muzzle, then seated it on the powder.  Aiming at his target, I punched it into the middle of the 10 ring.  I was especially glad the range god's smiled on me and put the ball where the 'effect' would be best felt.  He mumbled something about A--hole and went back to shooting.

I had done a lot of shooting with this rifle before coming up with a useable load - one fairly easy to load, was accuracy and that ended up winning me a 'lot' of booty in those early years.

 The first 5-shot target I shot with this rifle, offhand, at 25 yards is shown below - it was with the .457" ball, a .020" denim patch, spit lubed with 75gr. 2F shows, with enough 'play', even a barrel that shouldn't shoot, will.  The experience with this barrel, is what 'fouled' my experiments with the deep round bottomed rifled .50 I attempted to get to work.  I found no combination I could get to seal in that .50 and slightly oversized ball moulds were not to be had at that time.
« Last Edit: March 13, 2009, 05:01:05 PM by Daryl »

Offline hanshi

  • Hero Member
  • *****
  • Posts: 5310
  • My passion is longrifles!
    • martialartsusa.com
Re: Let's Compare Rifling Types
« Reply #16 on: March 13, 2009, 07:46:43 PM »
This is a little off subject but since we're talking about rifling types, can anyone tell me the pros & cons of "gain twist" rifling?  I have a marvelously accurate rifle with gain twist rifling but can't say it's anymore accurate than some others I have.  I'm just not that good a shot.
!Jozai Senjo! "always present on the battlefield"
Young guys should hang out with old guys; old guys know stuff.

roundball

  • Guest

Offline hanshi

  • Hero Member
  • *****
  • Posts: 5310
  • My passion is longrifles!
    • martialartsusa.com
Re: Let's Compare Rifling Types
« Reply #18 on: March 13, 2009, 09:50:49 PM »
Answered my question, fine.  I bookmarked the site.
!Jozai Senjo! "always present on the battlefield"
Young guys should hang out with old guys; old guys know stuff.

Offline Ken G

  • Hero Member
  • *****
  • Posts: 5526
  • F & AM #758
Re: Let's Compare Rifling Types
« Reply #19 on: March 13, 2009, 10:24:48 PM »
Thanks roundball.  I didn't know colerain had a website. 
Ken
Failure only comes when you stop trying.

roundball

  • Guest
Re: Let's Compare Rifling Types
« Reply #20 on: March 13, 2009, 10:49:43 PM »
Just out of curiosity...what is the correct way to pronounce their name?


Is it:   Cole - rain


Or is it:   Col - er - ain

David G

  • Guest
Re: Let's Compare Rifling Types
« Reply #21 on: March 14, 2009, 02:55:38 AM »
I've always heard and pronounced it Cole-rain.

Daryl

  • Guest
Re: Let's Compare Rifling Types
« Reply #22 on: March 14, 2009, 05:32:48 PM »
Flintr- The advertising is slightly incorrect in the wording for powder burning . The gain twist of 96" to 48" will burn X grains of powder more efficiently than will a straight 96" twist, due to increased resistance to the charge's development, however, it will not produce as much resistance to the powder than a straight 48" twist.

It would be fun to test one, though.  I'd like something in the 140" twist rate, accellerating to about 1 in 75" or 80" for the last 6" of the barrel - barrel length 30" to 32" in 16 bore. Rifling depth only .004" to .005" wide flat bottomed grooves almost bore diameter at the middle (H.M.Pope rilfing) and very narrow lands tiny radiused corners.  I think a barrel like this would be perfect for a Sporting Rifle.

Offline hanshi

  • Hero Member
  • *****
  • Posts: 5310
  • My passion is longrifles!
    • martialartsusa.com
Re: Let's Compare Rifling Types
« Reply #23 on: March 14, 2009, 06:04:40 PM »
Daryl, I had "heard" long ago that gain twist was suppose to be easy on patches more so than straight rifling because the ball/patch started off gently.  I really can't say I ever noticed a difference.  I know it has been used in modern cartridge rifles but is rare these days.  Seems to me if it offered a solid advantage it would be more popular.  It doesn't actually hurt accuracy in my experience.
!Jozai Senjo! "always present on the battlefield"
Young guys should hang out with old guys; old guys know stuff.

Offline Dphariss

  • Hero Member
  • *****
  • Posts: 9741
  • Kill a Commie for your Mommy
Re: Let's Compare Rifling Types
« Reply #24 on: March 14, 2009, 07:21:13 PM »
Thoughts on barrels and rifling.
With a PRB almost anything will work.
Too shallow, under probably .006 is bad.
Other than that any rifling form will shoot.
Care in MAKING the barrel and the uniformity of the material its made from will make the real difference.
Personally I do not like really deep grooves or wide lands.
.008-.010 deep wide grooves narrow lands.
But others works just as well accuracy wise.

Dan
He who dares not offend cannot be honest. Thomas Paine