Shallow grooves and roundballs...

[Skychief]

Had a great day shooting with a friend.

I was using a shallow grooved rifle and have some thoughts to share.

Typically, we think of round ball rifles as needing deep rifling.

What I have found is that this particular rifle shoots as well as and better that some of my deeper rifled "roundball" guns.

It hit a pie plate at 150 yards off the bench with great regularity.  I ended the session after hitting the plate 8 times in succession.

Cleanup is a snap as compared to my other rifles with deeper grooves.

I am beginning to think the idea of deep rifling being needed for accurate roundball shooting is mostly bunk.

What say you?

Best regards, Skychief.

[volatpluvia]

Skychief,
Back in the eighties I read an article by whoever it was that called for keeping the rifling shallow for round balls.  My experience is almost completely with deep grooves.
My very first flinter, a cheap kit, I won't say whose, had rifling so shallow as to be almost non existent.  It did not shoot well, but then I almost did not become confident of the lock lighting the pan.  And I was experimenting alone with no guide.  I just read as much as I could find on magazine racks in gun shoppes. 
So my experience is inconclusive.
But I am glad to hear that yours shoots well.
volatpluvia

[smylee grouch]

I have had a few shallow groove barrels and they both shot real good but I had to work up the best load for each just as you would for a deeper groove barrel. If your rifle dosent shoot well with deep or shallow grooves, it might just be a matter of load development.

[Skychief]

I measured the groove depth this evening and it was deeper than I had supposed.

It measured .009" in depth.   Not exactly fly "shallow".

[rhbrink]

I have a older Douglas barreled half stock in 50 cal that has very shallow rifling I would guess .005 to .006. It has always shot well for me while at the range I always wipe between shots, a safety factor for me. While hunting it has never needed more than one shot to kill a deer anyway.

I also helped a friend last year with a Euro made plains rifle that he wanted to take deer hunting this is a 48 inch twist and again very shallow rifling. We started off with a .490 ball and heavy patching shooting 70 grains of 2 FF wiping between shots and he could hold a 3" group at 75 yards easily enough with what I thought was rather poor factory open sights. More than good enough to hunt with and he did kill a deer with it too!

I would rather work with .008 to .010 rifling or deeper but very shallow rifling can be made to shoot. Probably would have to pay a lot more attention to the fouling build up in the barrel and wipe the bore often but I do believe that they can be made to shoot.

RB

[Hungry Horse]

 R.B. said it all, when he said "swabbing between shots". Thats the deal with shallow rifling. I have an old T.C. Hawken that somebody cut down for a youth. Its rifling is so shallow that you have to put a really tight patch on the cleaning jag to get it to follow the rifling twist. But, if you swab it out after every shot, it shoot very well.
 I also have had other shallow rifled guns that shot well, but I didn't want to fool with swabbing the bore all the time on a trail walk. I also found that with hunting charges they tend to foul to the point that a quick second shot is pretty hard to load.
 Some of the early target shooters at Friendship were known to freshen out their barrels after a match one day, in preparation for the next days shooting. I think they were not doing a lot of passes down the bore, but simple sharpening the shallow rifling.

                    Hungry Horse

[Ron T.]

Skychief...

Actually, the cotton patch you put around your rifle ball is what engages the lans in your rifle's barrel.  Thus, the thickness of the patch-material you use is fairly critical.

I chose my patching material by using a micrometer to measure the actual "compressed thickness" of the cotton denim patch material at the store.  I checked the material's thickness by screwing the micrometer's "jaws" down HARD on the cloth to see how much the cloth would "compact" under heavy pressure.

I chose to use .016-inch cotton denim material with a .490 inch .50 caliber Hornady swagged pure lead rifle ball in my .50 caliber older CVA Hawken cap-lock.

When tightening the micrometer's "jaws" down TIGHTLY on a single layer of the cloth, it measured just .006-inches whereas with barely tightening down and just "touching" the cloth, the cloth measures .016 inches.

When you push a lubed, patched rifle ball down your rifle's barrel, the lubed, patched ball should have a fair amount of "pressure" on the cloth so that the cloth will fairly-tightly engage the rifle barrel's lans & grooves which make up the barrel's "rifling" which, in turn, puts "spin" on the rifle ball thus helping the rifle ball "fly" more accurately into the target.

If the patching material isn't thick enough, it loosely engages the barrel's lans & grooves and doesn't impart as great a force of spin on the rifle ball which can often cause "problems" with accuracy when, in fact, the powder load is actually VERY accurate IF the patch was somewhat thicker.

Of course, if the patching material is TOO THICK, it's very difficult to push the lubed, patched rifle ball DOWN the barrel which means extra work and possible problems like NOT getting the rifle ball ALL THE WAY DOWN the barrel thus setting you up to end up with a "bulge" in your rifle's barrel because the rifle ball was NOT fully "seated" down on the black powder in the base of the barrel when you pulled the trigger and FIRED the load.

Obviously, this is NOT "good" for your rifle's barrel and is likely to cause unwanted accuracy problems PLUS a possibly ruined barrel !~!~!

The proper "feel" of a properly patched rifle ball is that it should "resist" allowing you to push it down your rifle's barrel, but not-too-much "resistance" to the point of being REALLY HARD to do.  You should NOT have to beat the end of your range rod with your hand or a rubber hammer to get the ball to completely and solidly seat on the powder load.  By the same token, the ball should NOT seat "easily", either.

With a little effort and, perhaps, some help from a more knowledgeable muzzle-loader shooter, you should be able to determine a proper thickness for your patches.  Once you are using the "proper" thickness of your patching material, you should see a reasonable increase in your rifle's shot-to-shot accuracy IF you are doing YOUR "job" with aiming, breathing and trigger control.

I hope this helps you to do better...  


Strength & Honor...

Ron T.

[WadePatton]

.... Probably would have to pay a lot more attention to the fouling build up in the barrel and wipe the bore often ...

Matching the ball and patch to the barrel, properly, eliminates this "wiping".  Then the charge can be varied to make for accuracy.

a recent quote from a top shooter

I started at 20gr. 3F and a patched .311" ball in my .32 Tenn. rifle with a cut rifled barrel- .008" rifling, very narrow grooves - opposite what I prefer.
At 25 yards, it would, of a bench, put 5 consecutive shots into a .45" hole. That grouping would measure .139" on centre to centre measurement.

At 50 yards, that 20gr. charge shot those .311" balls with .020" patch, into 2 1/2"- in other words, to obtain accuracy at 50 yards or further, I needed MORE powder.

When I hit 35gr. 3f GOEX, same ball and patch, the rifle gave me consistent 1" groups, on centres - ie: all into a 1.311" group.

When I sent up in ball size to .320", same patch and maintained the 35gr. 3F load, the ground enlarged to 1 1/2".  As I increased the powder charge to 40gr., the group then decreased in size to just under 1".  The increased accuracy and velocity will now make the right slightly better for woods walks, locally & at Hefley, as ranges run up to 110yards, or so.

With the loads listed above, I used the rifle's hickory rod without any trouble loading. I also used a short starter with a 6" main shaft to get the patched ball well down into the bore before using the rifle's rod. The 'purchase' of the rod in the bore helps protect the rod from damage.

As no time did the rifle need wiping while shooting - as only one shot's fouling was in the bore at any one time and that, being damp from the lube, was easily pushed down with the next patched ball when loading.

IF your .32 'fouls and needs wiping' YOU ARE DOING IT WRONG.

Even at 40gr load, my .32 is my easiest loading rifle.

in my most humble opinion, of course.

Of course, this is for high velocity shooting for trail walk and "accuracy" shooting - as in bunny or squirrel heads at 50 or 60 yards.  It also hits the bunny target at 100yards with regularity.  My rifle will not shoot accurately with light loads, past about 30yards. It just goes to pot.

I included the full quote for context and emphasized parts of it.  Some of us are trying to expand the realm of those shooters who never _need_ a second wipe because the loading patch does all the wiping necessary.  Shoot all day, clean when you are done, with no special regard to caliber or groove depth.  The evidence and practitioners of this are all around us.  If you look.

[hanshi]

I like a rather tight prb fit similar to what Ron T described.  The fit has to be tight enough to keep the bore clean when the prbs are seated; this keeps me shooting without having to wipe the bore.  Any load I use MUST be able to be safely seated with the wood underbarrel rod.  The tighter the load the cleaner the bore stays.

Rifling on the fairly deep side works best for me.  However, rifling as shallow as .006" can give superior accuracy with a good, snug load.  My .54 US M1841 rifle has rifling right at .006" deep and it will shoot 1" groups at 60 yards; that's as good as any custom rifle I own.  IMO rifling should be at least .006" deep and no faster than 1-48" twist for sure fire accuracy.  The aforementioned 1841 has a 1-66" twist.

The .50 swamped Rice round bottom barrel in my cabinet shoots exceptionally well, although I don't really know the exact depth of the grooves.  I'd call it the deep end of the scale with .006" being the most shallow.

[mjm46@bellsouth.net]

Back in the early 70's I had a Dixie Gun Works Pennsylvania Flintlock. The rifling was square bottom grooves, and somewhat more shallow than what I shoot today. When I got my first rifle with round bottom grooves, it threw me for a loop and I had a whole new learning curve. The thin patches I was using didn't work at all in my new rifle.

That old rifle shot very well. The lock was not very good but the barrel was super. Some low down skunk liberated that rifle and a Brown Bess musket from my home in 2006. I still miss them.

One of these days I want to try Rice's Builders Barrel. It has somewhat low square grooves.

[Daryl]

Micah - those builder's barrels shoot VERY well indeed, as-do their rounded rifling, but, I feel the squarish, shallower rifling has an accuracy potential advantage.  If the deeper grooves were more accurate, the bench, chunk and plank shooters would use them.

I have an Italian Model 1861 (Musketoon), ie: .577. The 24" bl. is VERY short and the sights are VERY close together. This rifle has the same rifling as the originals and same as the reproductions made by Parker Hale years ago.  

The rifling is .003" deep at the muzzle and .011" deep at the breech.

I smoothly radius crowned it's muzzle - then I found it really liked 80gr. of 2f and a VERY tightly patched .562" ball. Yes - a starter is necessary.

I started off using a .575" ball from a 4 cavity mould owned by my late friend, Brad, because I did not own a ".58 mould of my own at the time I traded into this rifle. The balls from Brad's mould would actually sit on the muzzle bare, as this rifle's bore is a tight .574"(all the way to the breech, of course).

I used a 10 ounce denim patch, which of course required a good blow of my hand to get started into the bore.  After receiving my .562" DC Lee mould, which cast .564" X .564" round from both cavities, I switched to those balls - still with the 10 ounce denim which I make out as .0225", crushed in my calipers as hard as I can squeeze the tines with my oversized fingers.  I also used the softer material we call Railroad Mattress Ticking, which I make out at .0235" thick as I 'felt' it shot better, but since we cannot get that material any more, I've gone back to the 10 ounce denim .
Once started(conformed to the bore at muzzle and 'put down' 5 or 6", due to the ever deeper progressive depth rifling, the ball goes down to the powder easily.   When fired, it must obturate as the patches are never burnt nor scorched.
 
With 80gr. 2F, this rifle will make 3", 5 shot groups at 100meters for me, with regularity, off a bench.  To me, with my eye sight, it is amazing I can shoot this short barreled rifle with is military sights so well. It has won be a bit of GOLD at Hefley Creek Rendezvous- just about every time I used it, this rifle put me in the top 3.

Of course, it never needs wiping while shooting- even though the rifling is supposedly .008" deeper at the breech than at the muzzle. I did not measure it with the plug out, but a bore scope easily showed the rifling getting deeper while the bore remained true. It should gas cut, but didn't - perhaps due to the VERY tight bore fit?

.564" + .0235" + .0235" = .611"
.574" + .003" + .003" = .580"
.611" - .580" =  .023" divided by 2 = .0115" compression per side in the bottom of the grooves, at the muzzle.  This 'compression' when initially seating the ball into the muzzle, will sightly elongate the ball and patch as it conforms to the grooves. In effect, this converts it into a short round ended bullet shape. This 'longer than normal' fit to the bore, must be the reason the ball actually does obturate, whereas loose fitting round balls seem not to.  Once started, it actually loads easily with the rifle's steel rod of course.

[tricorn hat]

The great Bill Carver took the National Pistol Championship many years in a row and kicked butt generally with pistols he made with 45-70 barrels.VERY shallow rifling. But then, Bill whipped 3 police teams with a sleeved Wogdon flinter!!

[Daryl]

Tricorn- using .45/70 barrels, ie: 20" to 22"with .004" rifling was the norm back in the 70's for pistol barrels.

Nowadays, many barrel makers turn out fast twist shallow groove barrels specifically for making pistols.  If/when you drive that ball at rifle speeds, slower twists give better results.  I have a fast twist .45 for target shooting, as well as a 60" twist .54 barrel for that pistol that shoots well with 60gr. 3F. It matches my 4" .44 mag. for speed. Shot of sand bags, the .45 will make a 1" to 1 1/4" hold for 5 shots. To shoot into 2" at 25 yards with the .54 and it's slow twist, I need 60gr. 3F.  Yeah - it snorts.

With tiny pistol charges, ie: 20 to 25gr. in the .45's for example, the ball and patch combination can be less tight and thus easier loading than what a 50gr. charge would require, simply due to the lower pressure.

My own .45 pistol (.005" depth and 18"twist )uses 25gr. 3F with a .020"  8 ounce denim patch.  It loads easily with this combination.  My .45 rifle (.010" depth and 60"twist) will shoot this same thin patch if I increase the ball size to .445".  If I don't increase patch thickness, accuracy suffers due to unexplained flyers (holes out of the normal group, up to 2" out. After increasing the patch thickness, no more flyers - nice round groups as you'd expect - and no wiping while shooting groups.

Taylor just finished re-furbishing that rifle for me. It had "some" issues. Can hardly wait to get out and test her.

[Dphariss]

I measured the groove depth this evening and it was deeper than I had supposed.

It measured .009" in depth.   Not exactly fly "shallow".

Anything at or over .008" is fine for a RB.

Dan

[T*O*F]

Once started(conformed to the bore at muzzle and 'put down' 5 or 6", due to the ever deeper progressive depth rifling, the ball goes down to the powder easily.   When fired, it must obturate as the patches are never burnt nor scorched.

I always wondered why, if the patch is what grips the rifling, why does your ramrod push the load straight down instead of spinning?

[Standing Bear]

Rod tip slips on the ball n patch

[hanshi]

I gotta do more research; my .54 could be .008" rather than .006".  I recited the original figure from memory; and my memory ain't what it use to be.

[Daryl]

Once started(conformed to the bore at muzzle and 'put down' 5 or 6", due to the ever deeper progressive depth rifling, the ball goes down to the powder easily.   When fired, it must obturate as the patches are never burnt nor scorched.

I always wondered why, if the patch is what grips the rifling, why does your ramrod push the load straight down instead of spinning?

Dave- I'm quite sure the ball does rotate with the patch in the rifling and that the brass cupped rod tips I use, easily allow the ball to spin.  I've thought about that as well.

Also, I am sure with some of the ball and patch combinations being used out there, that some balls do not spin with the rifling as they are seated. I expect the spinning is an easy result with a tight combination.

Try holding the rod from turning as you are cleaning or drying the bore and I'm sure you will split the rod- that is' if you can stop it from spinning. It will normally only turn 252 degrees anyway - 60" twist and 42" of length.

[smokinbuck]

I use one of the jags that lets the tip rotate wether the rod does or not. Follows the rifleing wether loading or cleaning. Can't remember the name.

[Daryl]

In retrospect, the fact that jags screwed into rod tips will loosen in the threads when loading in a left a left hand twist barrel or when cleaning, right or left twists shows the jag is rotating and actually unscrewing the jag fromt eh cleaning patches grip in the lands.  If this isn't happening, you aren't using a tight enough patch. imho