Round Groove Patch Thicknesses

[Rokon]

Does anybody have a rule-of-thumb for the beginning patch thickness for a round groove barrel vs a square groove barrel?

 

[Grizzly Adams]

My .45 colerain barrel likes a .440 ball and a .020" patch.

 

[azmntman]

If I had a rule of thumb it would be a difficult to hard start with my thumb in a clean bore. That's what I try for in all mine round/square or otherwise.

 

[Grenadier1758]

I find there are two parts to the rule of thumb.

When hunting, you should be able to easily use your thumb to start the ball and patch for the second shot.

When shooting targets, it should be difficult to thumb start the ball, but the patches should not show signs of cutting when recovered after shooting.

Not much help really. Patch selection depends on the depth of the groove. Use a slightly thinner patch for round groove barrels such as 0.015 instead of 0.020". Ultimately it is the results on target that provide the best answer. If the accuracy meets your needs, then you have chosen the correct patch.

Lubrication of patches is an entirely different thread.

 

[Loyalist Dave]

I started out using .012 pillow ticking, and a .490 ball in a square cut barrel. Then I got a .54 so went to a .530 ball, but used the same ticking...I need a bit more than my thumb to start the bullet, but the paper targets and the deer get hit where I aim...and if I miss or throw a shot off the mark, it's me and not the load or the barrel.

LD

 

[smoothshooter]

I like a thicker patch that holds more lube so I don't have to wipe between shots, and this means .015" to .020" most of the time.
Reduces patch cutting and burn - through as well.
I get very good accuracy and can fire dozens of shots without wiping.

 

[Jim C]

Just for the sake of curiosity, my rifles will allow me to deviate from their favorite ball size, patch thickness, lube combination, that one particular one that produces their best accuracy, but only at the cost of less than best accuracy. Do you find that to be the case as well with your rifles?

 

[roundball]

As one reference, I used .018" pillow ticking in all my square bottom groove barrels.
When I replaced them all with round bottom groove barrels, I had to go to .028" pillow ticking patches

 

[hanshi]

No rule of thumb, but I use a .024" patch in both my round groove AND square groove barrels. For instance; in my .50 with round grooves I use a .490" ball and a .024" patch. A little tighter in the square barrels and a little easier in the round ones.

 

[Jim C]

That makes me wonder how it manages to squeeze all of that extra patch material in between the ball and lands, given of course that the bore dimension/ball diameter remains exactly the same.

 

[Zonie]

If the ball is made out of pure lead, the ball diameter does change when it is rammed down the barrel if it is patched.

The patch will even leave an impression of its weave on the outside of the ball.

That is why a thinner patch or smaller ball must be used if the lead is a hard alloy like wheel weights or commercially cast pistol bullets.

 

[roundball]

That makes me wonder how it manages to squeeze all of that extra patch material in between the ball and lands, given of course that the bore dimension/ball diameter remains exactly the same.

Most of the snug resistance seating a ball in a .010" square groove barrel comes from all the extra folds of patch material having t be compressed / jammed down into the groove space.

Round bottom groove barrels have much deeper grooves...for example mine are .016" deep...so there's an additional .012" increase in groove-to-groove depth / space to fill back up with patch material to get that same snug PRB fit.

 

[zimmerstutzen]

Most but not all round bottom groove rifle barrels have narrow grooves of a radius that is less than bore radius. A few however tend to have wide grooves with a radius two or three times larger than bore radius. Such barrels often do better with a thin patch and larger ball.

 

[Hunter John]

Never heard of pillow ticking that thick. Not trying to be a stickler, but do you mean mattress ticking at 0.028?

If you do in fact mean pillow ticking, where did you happen to find it that thick? I've bought more than my share at Wally World and Jo-Ann Fabric and have never measured anything that thick.

 

[roundball]

1) My round bottom groove barrels are from Rice and Rayl, about as good as they come and they were both noticeably "roomier"...had to go to a much thicker patch;
2) Got a 10 yard bolt of it from Jo-Ann Fabric...assumed it was blue striped pillow ticking...don't know if it was actually called mattress ticking, never cared, LOL...as I recall, it was .025" at the store, and washed/dried/lubed is .028".

 

[jamesthomas]

Yep, it is really mattress ticking, I use .024 in my .50 cal. Green Mountain barrel with .012 grooves and a .490 round ball, and use the red stripe Pillow ticking .015 in my .40 cal. with a .395 ball in a Dehass barrel. Both are a very snug fit that will squeeze any excess lube out of the patch.

 

[hanshi]

I have to go to Joann's for material. I've bought lots there (blue stripe) that measured .015" and later found some blue stripe at .024". Last time I went there I bought some brown stripe ticking at .024". I suppose then that it's mattress ticking?

 

[Hunter John]

Yup, that's my guess. I've only used pillow ticking 0.015-0.018 so far....a few yards from Wally Word and JoAnn's. Next time I'm at JoAnn's I'll include about the mattress ticking which is advertised to be about .007 or so thicker and also about double the price of the pillow ticking on JoAnn's website.

I have 2 very large pieces of 30 year old canvas painter's drop drop that my 85 year old dad almost threw out....almost. It measures 0.030 or about double the thickness of pillow ticking. One day for the heck of it, I used 2 of the drop cloth 0.030 patches and a 0.440 RB in my 50 cal hawken. With 35 gr FFF Goex it shot outstanding groups at 25 yards...say around 1/2 inch. To be honest, those groups were better than anything I ever shot with my 45 cal Seneca with pillow ticking and with/without felt buttons !!

Don't be afraid to experiment guys with using various patch material. As long as it's cotton, tight weave, and tough, you just may surprise yourself if you try shooting 1 caliber size ball in the next higher caliber barrel.

When I have a chance this summer on the range I'm gonna try using 2 thick 0.030 drop clothe patches, a .490 RB in my Lyman .54 trade rifle.

 

[Jim C]

Very interesting as I've often wondered about shooting an undersized ball with thicker patching, ie a 45 in a 50, but have never tried it.

 

[Bob J]

I went to patches made from chamois in my round groove Rice .62 barrel - it compresses easy so that I can thumb start the ball and still get good accuracy.