patch and ball size?

[MattyB]

I finally measured the ID (groove to groove)of the barrel on my 1803 HF. It's .542-ish. What size patch and ball should I use? I now have .535 balls and .015 patches, but it's awfully hard to stuff down the tube. Thanks for any help.

 

[rabjr]

A .010 patch with a bore button might work out for ya or ya need to get smaller ball. I don't like to use anything thinner than .015 for a patch myself.

 

[roundball]

I don't like to use anything thinner than .015 for a patch myself.

Amen...I'd use .530's & .018" with a short starter

 

[Russ T Frizzen]

I'd go with this set up too. There's just no need for a super tight load unless you're in a target match. I personally work up loads that are accurate but that I can start with my thumb. I can hit what I aim at and even shoot recognizable groups, but it makes my life easier.

 

[paulvallandigham]

I agree with Roundball on this. When you venture down to the .010" thick patching, you risk the patches tearing, or burning as they go out the bore.

Measure the Land to Land diamater( That is the high flat places in the bore.) Then look for a ball that is no less than .010" and better at .020" smaller than the land diameter. The difference between the land( Bore ) diameter, and the groove diameter, divided by 2 give you GROOVE DEPTH. That tells you how much thickness of patch is needed to fill that groove in addition to grabbing the ball and imparting the spin of the lands to the ball.

NOTE that wet or greased cloth patches tend to stretch or " compress ", so that you can use a cloth patch that is thicker than the difference between ball diameter and groove diameter.

For example, with a .540 Bore Diameter, and a .552 Groove diameter, you have grooves that are .006" deep. Use a .530 ball, and a .015 or .018" thick cloth patch, wetted, or greased, to wrap the ball. YOu need to come up with .552" in patch thickness and ball, combined. However, remember that the patch is going to contact the barrel on two opposite sides.

So, it works out this way. .540 minus .530 give you .010" of play between the ball and the lands. There is an additional groove depth of .006", or a total of .022" of area that must be filled. ( .010 for the land, and .006" for the groove depth times 2!)

Wrapped around that .530 ball, a .015" patch will provide .030" of fill for the space provided. But, in my example, This is only .008" thousands over the total width of the grooves, or .004 per groove on each side. That is an amount of Compression that is easily within the means of a wetted or greased cloth patch. In fact, I agree with Roundball to try the .018" patches, simple because your groove diameter will probably handle that thickness, too. The thicker the patch, the better the gas seal.

As to patch cutting, many guns have poor muzzle crowns, and its that fact that has the thicker patches being cut, at the muzzle, and makes it more difficult to seat the PRB. Try a 60 degree angle crown, and you should find seating the ball without damaging the patch to be much easier with the thicker patch.

Oh, I think you may be confused as to what is the groove and what is the land. When you look at the muzzle the lands are the raised portions of the rifling, and the grooves are the cuts between the lands. When shooting modern pistol bullets, for instance, its the lands that leave the " GROOVES ON THE BULLET" and the grooves in the barrel leave the high portions on the side of a bullet. Don't confuse the two.

I can't imagine a .54 caliber rifle having a true groove diameter of .542"ish". That would be grooves of only .001" on each side of the barrel. Notebook paper is .003" thick!

I suspect that what you measured instead was the land or bore diameter. Sometimes holding a caliper steady as you measure the land diameters gets a bit tricky, and its not unusually to see people give readins larger than what the actual size is. It takes a practiced touch on a caliper to get the correct measurement.

I demonstrated that fact to another member of this forum several weeks ago, when he brought his gun to my home to measure the bore. His bore was smaller than the nominal diameter for that caliber, explaining why he was having a tough time seating RB of the recommended size.

Best wishes. :thumbsup:

 

[jtmattison]

I don't like to use anything thinner than .015 for a patch myself.

Amen...I'd use .530's & .018" with a short starter

I'm with y'all. I use .535's with pillow ticking in my .54's. They take a whack to get started but the effort pays off in accuracy.

HD

 

[CrackerJim]

Although loading and shooting are going fine, I'm curious as to how my barrel measures out. My problem is that the lands are cut such that the lands are not opposite each other to get a reading.

I was thinking of putting some type of spacer on one "side" of the circle of the bore and measure the difference in land and groove from the spacer to calculate.

Suggestions?

Thanks,

Jim

 

[BrownBear]

Hey Jim-

The easier way is to get an oversize tear-drop shaped fishing sinker--- the ones with a brass wire through the middle that's twisted into a loop on the small end of the sinker. The closer it is to bore size while being a little larger, the easier it is to use. Push the sinker into the bore and use the brass wire loop to help pull it out again. Then measure the engraved end of the sinker to get at bore size.

 

[jtmattison]

Can you measure land to groove and then groove to groove? If so, take the difference between the two and you'll have both measurement you're looking for.

HD

 

[paulvallandigham]

YOu can also measure the groove to outside flat dimension, and then the land to outside flat dimension, and subtract the the one from the other to obtain Groove Depth. Now take the land to groove dimension and subtract the groove depth, and that will give you the bore diameter( Land to land in barrels with uneven number of grooves and lands.)

If you worry that one of the flats may not be as " thick " as the others, then measure the groove to outside flat on several grooves, and see what you get.

 

[Zonie]

Trying to bridge the groove with a rod of known diameter will not give a good reading if the rifling grooves have any width to them .

For instance if you were measuring a .500 diameter bore with a 7/16 diameter drill bit bridging a .100 wide rifling groove, the drill will move downward into the groove .0058.
If you weren't aware of this movement into the groove and measured the distance from the top of the drill bit shank to the inside of the bore and then added this measurement to the drill bit shanks diameter the calculated answer would be .0058 larger than the bore.

Using a smaller drill bit shank doesn't improve things. In fact, it makes things worse.
A .250 diameter drill bit for instance in the above .500 diameter bore with .100 wide rifling grooves will move down into the groove .0104.

To calculate the effect of the width of the rifling grooves on a rod of known size take 1/2 of the rods diameter and multiply it times itself. Save the answer. Then take 1/2 of the groove width and multiply this times itself. Subtract this from the first saved answer and take the square root of this new answer. Then subtract this value from the rod radius (1/2 the rod diameter).

Hoping there isn't any measurable runout between the bore and the outside flats of the barrel, using paul's method is probably a more accurate method unless you want to measure the width of the grooves and go thru the calculations to determine their effect on the final answer.

 

[laufer]

.53 with .018 works the best for both of my rifles, .53 with .015 a little off, but still tolerable at 100 yards. try different combinations and fidn the best one for your set up and have fun!!

 

[CrackerJim]

Thanks guys, good ideas.

Jim