How do you measure the bore in a rifle?

How do you measure the bore in a rifle? I have a good micrometer. Land to land? Groove to groove? Land to groove?

Does this muzzle needs some work?

Land to land, I'd leave the muzzle alone until you see if it is cutting patches...Once you determine the bore and have a mold, load a ball with a strip of ticking about 12 inches long and then pull it out...Look at the ticking and see if it is cut...

Pin gauges, the "minus" variety.

Don't F with it until you have shot it extensively and exhausted every reasonable option.

With your supplied photo? That octagon barrel should be measured,
,Land to land.
And Yes, that muzzle needs some work. If it is antique, then proper consultation should be found before restoration is attempted.

It looks like there is a couple of nicks in the muzzle that could cause cutting of the patch when loading. Have a gunsmith crown it if you don't know how. It looks like the barrel channel was filled in with a chunk of wood and a different barrel installed. I have a couple of half stock originals that have mixed parts from back in the day. Can you post pictures of the rest of the gun?

nchawkeye said:

Land to land, I'd leave the muzzle alone until you see if it is cutting patches...Once you determine the bore and have a mold, load a ball with a strip of ticking about 12 inches long and then pull it out...Look at the ticking and see if it is cut...

Click to expand...

Measures land to land .528 inch. Ball is .532 and 50 grains of ffg. Patches are blown through, but not really cut by the rifling. My mentor suggested we try cornmeal and a thinner, maybe tee-shirt patch.

Did strip with ticking, .018, pushed a ball to flat with the muzzle and pulled it out. Was very difficult to pull out the ball, but the ticking did not cut. A knowledgeable person did this. BTW having a problem with fouling. Dirty residue (black) from three shots.

I guess the muzzle at .528 land to land and a patch of .018 over muzzle would equate to .036 plus .528 would be .564.

Overall the ball is harder to start for about the first 7 few inches, then gets easier. Lubed with 1:9 Barristol to water. Bore looks clean and bright. No rust or pitting. Yes, it is an antique.

I am planning to shoot it more. Will not do any modification. If needed it will be done by a qualified gunsmith.

All the above is just my conjecture. I am new to ML and I may be 'way off base. Please help me, thank you very much!

Norman Brooks said:

It looks like there is a couple of nicks in the muzzle that could cause cutting of the patch when loading. Have a gunsmith crown it if you don't know how. It looks like the barrel channel was filled in with a chunk of wood and a different barrel installed. I have a couple of half stock originals that have mixed parts from back in the day. Can you post pictures of the rest of the gun?

Click to expand...

Barrel channel stock seems very old and no new wood has been changed.

To my untrained eye there seems a few nicks in the muzzle.

Marplot said:

the ball is harder to start for about the first 7 few inches, then gets easier.

Click to expand...

It could be choke bored, not real unusual. That muzzle does need some work. As far as affecting collector value, that is a separate issue I am not qualified to speak to.

Marplot said:

Barrel channel stock seems very old and no new wood has been changed.

To my untrained eye there seems a few nicks in the muzzle.

Click to expand...

That is a nice gun. Side view of the Nose cap explains it all. Be very careful on crowning the muzzle, maybe just enough to take out the nicks.

Norman Brooks said:

That is a nice gun. Side view of the Nose cap explains it all. Be very careful on crowning the muzzle, maybe just enough to take out the nicks.

Click to expand...

Personally I would not be personally crowning the muzzle. I will get the right person to do this.

Marplot said:

I guess the muzzle at .528 land to land and a patch of .018 over muzzle would equate to .036 plus .528 would be .564.

Click to expand...

Seems like that would be mighty hard to load.
A thinner patch might help but your ball is still larger than your bore, albeit only .004".
My first thought is try a .520" ball, or even .515".
I have a percussion rifle with a .532" bore that I shoot .520" balls out of.
For hunting, .012" patch lubed with mink oil. I have shot this load up to 12 times without swabbing.
For target, a .015" patch lubed with moose milk will shoot all day without swabbing.
Measuring patch thickness is another thing to get hung up on.
The .012" patches I use are are labeled as .015" and the .015" are labeled .018".
There are multiple ways to measure patch thicknesses. I just have a way of doing it that I feel consistent with so when I go to the fabric store with my micrometer I can get what I need.

Someone put a LOT of love into that rifle when it was being built, look at the detailed work in the side view of the muzzle, gorgeous! I'd exhaust all possibilities on finding a load before I modified the gun. It seems to me, too, that the ball is too large, a .520" should be about right, with some thinner patching. Experiment with your load components before you mod the gun!

kelvinator said:

Seems like that would be mighty hard to load.
A thinner patch might help but your ball is still larger than your bore, albeit only .004".
My first thought is try a .520" ball, or even .515".
I have a percussion rifle with a .532" bore that I shoot .520" balls out of.
For hunting, .012" patch lubed with mink oil. I have shot this load up to 12 times without swabbing.
For target, a .015" patch lubed with moose milk will shoot all day without swabbing.
Measuring patch thickness is another thing to get hung up on.
The .012" patches I use are are labeled as .015" and the .015" are labeled .018".
There are multiple ways to measure patch thicknesses. I just have a way of doing it that I feel consistent with so when I go to the fabric store with my micrometer I can get what I need.

Click to expand...

I will try these. I have a mentor that has a lot of molds, and we will keep trying to make it right.

centershot said:

Someone put a LOT of love into that rifle when it was being built, look at the detailed work in the side view of the muzzle, gorgeous! I'd exhaust all possibilities on finding a load before I modified the gun. It seems to me, too, that the ball is too large, a .520" should be about right, with some thinner patching. Experiment with your load components before you mod the gun!

Click to expand...

I have not the slightest intention to modify the gun. It is a matter of finding the right ball and patch.

Marplot said:

I have not the slightest intention to modify the gun. It is a matter of finding the right ball and patch.

Click to expand...

Good ..... Best of luck bud

I use casting lead, sometimes called chamber lead.
I take a coat hanger (wire) make a jag on the end with the wire.
tie a pile of cleaning patches onto it. stuff it down the barrel (with a 1/4 in dowel)
Then pour the casting lead down the barrel to the patches.
Wait till it cools and pull it out.
The lead will give you a mirror cast of your barrel. Measure what ever you want.
Be advised the further down the barrel you go the harder it is to get out.
This is designed for BPC chamber measuring, but we have used it on several bore stuffers.
*****************************************************************************
DOH
Oh I am such a dumb donkey.
The other way to do it, is to cast a ball with the above lead, stuff it down the barrel
then use compressed air to blow it into water or something soft and measure the ball.

An experienced guy can make cerosafe casts but it can go wrong. You risk loosing stuff in the barrel and scratching it with the wire.

The most direct way is to use a ball gauge. Adjust it to the bore diameter. Measure it. That is the bore.

Groove is a bit less straight foreword. I tend to use a digital caliper and record the widest measurement. Thread lightly so you do not scratch the inside of the barrel.

Do not muck with the crown. That is a job for someone with gunsmith or machinist skills.

Once you know the bore diameter you know what size ball. Select one that is about 0.010" under the bore diameter.

Select your patch by taking a piece of strong new patch material and put some oil on it. Try thumb pressing the ball in the muzzle. IF it goes super easy, gather the cloth and pull the ball out. Try again with thicker cloth. Do not force it our use a mallet. Remember you have to pull it out with the gathered cloth. Once you have a snug combo try that as a baseline.

You may want thicker cloth for top accuracy. Determine that with powder loaded first at the the range.

Any patch material that is under about 0.015" as measured compressed with a micrometer is probably to thin. T-shirt material is no good. You want ticking or canvas.