Sealing round grooves

[hortonstn]

i've tried about everything what do you think? i"ve got a rice 50 cal , a getz 54 ive tried small ball thick patch and large ball thin patch i just can't get the accuracy i can get in a
Green Mountain straight groove 45 and 50 cal these barrels are all 38-42 inches long
i test these benchrest style bagged in the ft.
i'm thinking a round groove barrel can't be used for bench or over the log is this correct?
shooting 60 yds open sights at a 3 inch target with a nickle sized bull
thanks for your thoughts
paul

[smylee grouch]

You might want to give the crown a real good polish job and try a 5 to 10 thousands underbore size ball with at least a 20/1000 denim patch. I'm thinking the bore will seal up better and load easier once you get the ball started and down the bore about 5-6 in with a short starter. Also try some different sight styles if your current ones are hard to see consistently.

[Scota4570]

I had a round bottom 45 caliber barrel.  The grooves were 0.016 deep and about 50/50 width ratio with the lands.  It shoot poorly.  No patch and ball comb helped.  That includes loads that required a heavy steel ramrod.  I tried thick cushion was under the patched ball too.  Nothing worked.  I scrapped the barrel, that was an effective solution to the problem. 

I do not think it is an issue with the shape of the grooves.  I think the grooves are too deep and too narrow.  A loadable combination that gets enough compression in the center of the grooves is not possible.   If they were made wider and not so deep I bet they would shoot.

To go to another extreme I have used 45 cal cartridge gun blanks to make MLs.  The grooves are only 0.004" deep (only 1/4 the depth of the round bottom barrels).  They have all shot very accurately. 

Others have other, equally valid opinions and experiences. 
 

[D. Taylor Sapergia]

I get superb accuracy with round groove rifling using a ball .005" under bore size and a .021" - .025" patch lubed with anything, as long as there's lots of it.  I use a short starter and the hickory rod from the rifle.  I also use charges that some may consider excessively heavy, ie:  65 gr. 3Fg in .40 cal, 85 gr. 2Fg in .50 cal, 127 gr. 2Fg in .62 cal.

[Daryl]

hortonstn - We have all heard how easy it is to clean deep, rounded grooves. That is an advantage, especially if you are bench, plank or chunk shooting where there is a lot of time
between shots and bores are wiped between shots. Makes sense that a bore that cleans easily would be an advantage to having identical bore condition for each shot.  This in itself
should be enough to promote deep, rounded rifling for those "accuracy" regimes, if they were also as accurate as shallower square (or slightly rounded) rifling.
I would think ALL BR, plank and chunk shooters would be shooting those deep, rounded grooves.
They aren't, thus there is a reason they all use shallower, square or slightly rounded (we call them square) rifling with sharp corners. They work.
Years ago, I received a barrel from a barrel maker, that was a prototype .50 cal., with .025" rifling depth.  I tried every combination I could think of, yet could not get that barrel to shoot to
my satisfaction.  Prior to that, I had a .45 cal. Bauska barrel that had .028" depth of rifling, that shot very well indeed. I was discouraged by the .50 not shooting well and did not know why,
except perhaps the lands were too wide in comparison to the grooves as I just could not load a combination that filled them well enough.
In the .45 that shot well, I was using a .457" ball and .022" denim patch.  As the bore was .448" plus the groove depth, I had .504" depth to fill. The .457" ball + the .022" denim went only .501"
which technically did not fill the grooves, but it shot well.
Here's a 5 shot, 25 yard group with that barrel, produced back in the mid 70's. lol - I could see well and didn't shake as much as I do today.



Now, here are the groups shot with a Hugh Tonges barrel with .025" rifling, with the load combinations listed on them.
Now, they aren't worthy of being BR quality, or even chunk, but these were not worked up, just selected and shot with a rifle I have never shot before.
The sights were typical V and front blade. Single bag on a 50yard target.
So- rounded grooves can shoot decently, especially for a hunting rifle.

[hortonstn]

Thanks for the advise
Paul

[rich pierce]

I had a round bottom 45 caliber barrel.  The grooves were 0.016 deep and about 50/50 width ratio with the lands.  It shoot poorly.  No patch and ball comb helped.  That includes loads that required a heavy steel ramrod.  I tried thick cushion was under the patched ball too.  Nothing worked.  I scrapped the barrel, that was an effective solution to the problem. 

I do not think it is an issue with the shape of the grooves.  I think the grooves are too deep and too narrow.  A loadable combination that gets enough compression in the center of the grooves is not possible.   If they were made wider and not so deep I bet they would shoot.

To go to another extreme I have used 45 cal cartridge gun blanks to make MLs.  The grooves are only 0.004" deep (only 1/4 the depth of the round bottom barrels).  They have all shot very accurately. 

Others have other, equally valid opinions and experiences. 
 

I can take that barrel and cut 0.005” off the lands with a freshing rod and I bet it will shoot.

[recurve]

Getz round bottom rifling with .020 denim 490 ball open sights 50 yrds

Bobby Hoyt round bottom rifleing 50 above 54 below same patch 50 yrds

[recurve]

green mtn square bottom rifleing 50 & 100yrds w peep sight same patch and ball as my round botom above

[WadePatton]

I had a round bottom 45 caliber barrel.  The grooves were 0.016 deep and about 50/50 width ratio with the lands.  It shoot poorly.  No patch and ball comb helped.  That includes loads that required a heavy steel ramrod.  I tried thick cushion was under the patched ball too.  Nothing worked.  I scrapped the barrel, that was an effective solution to the problem. 

I do not think it is an issue with the shape of the grooves.  I think the grooves are too deep and too narrow.  A loadable combination that gets enough compression in the center of the grooves is not possible.   If they were made wider and not so deep I bet they would shoot.

To go to another extreme I have used 45 cal cartridge gun blanks to make MLs.  The grooves are only 0.004" deep (only 1/4 the depth of the round bottom barrels).  They have all shot very accurately. 

Others have other, equally valid opinions and experiences. 
 

I can take that barrel and cut 0.005” off the lands with a freshing rod and I bet it will shoot.

This would be the next option I'd consider. Let Rich tune it up.

[smylee grouch]

Some years ago now the Minneapolis Museum of Art had the famous J. Kuntz rifle on loan from the Metropolitan Museum of Art in NYC. One of my daughters lives close by so we made the trip to see it. Alas they had sent the Kuntz rifle back to NY the week prior to our trip. But they did have a Dickert there and I got to see the muzzle up close. The round groves were more, how shall I say up and down and less " valley" shaped like some of the current barrels made. Makes me wonder if the more pronounced " up and down " groves might grip the patched ball better. If so the lands might be wider but if you cut one extra grove you could/would reduce land width I think. I'm also thinking this might make it easier to seal up the bore. 

[Daryl]

I tried to get a maker of custom rifled barrels to cut one with .008" to .010" depth, but with grooves with rounded corners.
He was of the opinion, that unless a barrel has .025" to .028" depth, it wouldn't shoot & thus, would not make me that barrel.
This type of barrel will shoot well, especially with snug loads. It would also clean up more easily, without sharp corners.
Doubled up flannelette on a jag cleans very well, rifling with normal sharp cornered grooves.

[Eric Kettenburg]

^^^

Yes, I know Bob Hoyt's "round grooves" and Rice's "round grooves" look to my eye more like square grooves with a rounded corner and a slight radius to the bottom, like you're describing, and they don't seem crazy deep although admittedly I'm not measuring them.  Colerain's grooves are like deep round rain gutters, and the grooves are usually close in width to the lands.  Rayl's round grooves are deep and very round, with lands wider than the grooves.  The round grooves Getz barrel used to cut were also more similar to Colerain's but I don't think they were quite as deep.

I prefer Rice's barrels to pretty much anything but honestly I've never had a problem with any barrel; however, I'm not a bench shooter and if I can keep my shots in a @ 4" to 5" circle with ANY open sight gun, I'm happy as a clam.  But then I don't use tight combos either.

Lots of German guns and definitely some early American stuff seems to have been made with fairly deep, round grooves i.e the MArshall gun, Shreit rifle, a few Dickerts I've seen, and some other stuff as well.  Probably all German import barrels on the American work.  I don;t think those guys were worried about putting everything into one hole, I think they were worried about "minute of deer" accuracy or "minute of native dude trying to kill me" accuracy.

[bob in the woods]

From the research I have done, it seems to me that owning an exceptionally accurate rifle was a real status symbol . 

[Marcruger]

My experience has been that some round-bottom-grooved rifles can shoot well.

That said, I believe it is much harder to get one to shoot well through load development than a square bottom grooved barrel.  Especially if the round-bottom-grooves are deep (like .016" or deeper). 

I had one deep round-bottom-grooved barrel that would not shoot no matter what I tried.  It was replaced. 

Conversely, I have found that Green Mountain barrels (square-bottom) are very easy to find a load which they like.  As my target shooting, medal winning friend noted once, "Look at what's on the firing line at Friendship. You'll see a lot of Green Mountain barrels. There's a reason." 

He has two .40 Colerain barrels that shoot super.  I looked it up and those barrels have .012 shallow round bottomed grooves.  They do not have square shoulders to the grooves.  Those shoot really well.  I think the key word here is "shallow". 

I personally see no point in deep grooves, round or square.  Just a bother to try to seal. 

Just my two cents worth.   God Bless,   Marc

[Marvin S]

You’re not the first or only one to have this problem. I have four radius groove barrels and two will shoot good and two are tomato stakes. I doubt I’ll take a chance on another one unless I can shoot it first.

[bob in the woods]

It's snowing and really cold here right now, so I'm not going to run out to the shop this moment, but will post a target tomorrow thatI shot some years ago with the same .54 Colerain barrelled rifle I still use today. The target was shot at 100 yards.  The .40 cal i used in a lot of the previous postal matches also has a colerain radius grooved barrel. I think the results speak for themselves.If anyone is unhappy with their r. grooved barrel, just send it to me rather than use it for a tomato stake. I'll reimburse you the postage 

[Daryl]

From the research I have done, it seems to me that owning an exceptionally accurate rifle was a real status symbol . 

As well as the person themselves being renowned for their marksmanship.  There were rifle clubs in California in the mid 1800's & likely elsewhere around the country
as well. By the mid 1800's, Remington was selling octagonal barrel blanks that were turned at the muzzle for a guide bullet/ball starter.  These show up now and then
of cap lock rifles in collections.

[Metequa]

Seems groove depth has as much or more to do with level of fouling tolerance than imparting spin to the projectile.  To me the paradox with round grooves is finding patch material dense enough to withstand the heat/pressure but with the ability to "fill" the groove, or put another way a patch "fluffy" enough to fill the deep round grooves but tough enough to withstand being compressed tightly between the lands and ball.  With a square profile not quite as deep I have an easier time finding a patch able to both fill the groove and be plenty tough for a tighter load combination.  Mileage varies of course...

[hortonstn]

These are some piks of days past younger and better eyesight  goodieon heavy bench

[smylee grouch]

Nice shooting Paul. 

[Daryl]

hortonstn (Paul) what sights are allowed in that discipline?

[hortonstn]

Daryl
These were redfield peep on rear anschutz ft globe heavy bench in friendship Indiana
The guys who won shot tighter groups than I but it was fun
Teflon .20 ticking was also used

[smylee grouch]

hortonstn, it sounds like you had a nice set up for sights and one of Jim's barrels. I had a light bench gun with one of his barrels and used a 10/1000 oversized ball through the false muzzle and that 20/1000 teflon patch. It was a great shooting gun but the competition was also pretty great. But like you said it was fun and very educational.

[hortonstn]

Daryl here's a pik


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