Chiappa barrel fit issue

[melnic]

OK,
So I thought I was chasing a minie ball issue this past few weeks but I think I found something that is having an effect on my groups.
This week, I took my first shot and it was centered up horizontally perfect. Then shots were all over the place. After a cease fire, The next shot looked pretty good horizontally then went all over the place again.
Well, when putting the barrel back together after cleaning, I normally would tighten the tang screw up AFTER the barrel bands were put on. Last night, I tightened up the tang and noticed the muzzle rise up.
This is a Kit I build (traditions kit) and I think the barrel fit at the breach is not correct.
Just see what was going on, I stuck a piece of brass sheet past the tang to keep the barrel from rising up when tightening up the tang. 2 pics before the shim and 1 after.
How do I mark the high spot in the breech area to sand down? any tricks?
Also, are there any prefered methods to getting the barrel fit into the stock decent?

[John Holland]

Personally, I think the best solution is to glass bed the entire barrel.

[Charlie Hahn]

Here is what to look for before you do anything. The barrel should be down on the bolster, and be laying down in the barrel channel. As it is right now determine if the bands are equally tight or one is tighter than the other. I would expect the barrel touches the area between the bands and has a gap under the breech. You can check this by putting a small ball of clay in the stock and press the barrel down until the bolster seats in the lock and the rear band can be slid on. Carefully remove the barrel and see how thick the clay is. This will let you know the barrel channel is too large in the breech area, and verify this is the issue. Once this is confirmed you should prepare the barrel channel so there is bare wood, and then glass the unit from tang to muzzle.

Charlie Hahn

[melnic]

Here is what to look for before you do anything. The barrel should be down on the bolster, and be laying down in the barrel channel. As it is right now determine if the bands are equally tight or one is tighter than the other. I would expect the barrel touches the area between the bands and has a gap under the breech. You can check this by putting a small ball of clay in the stock and press the barrel down until the bolster seats in the lock and the rear band can be slid on. Carefully remove the barrel and see how thick the clay is. This will let you know the barrel channel is too large in the breech area, and verify this is the issue. Once this is confirmed you should prepare the barrel channel so there is bare wood, and then glass the unit from tang to muzzle.

Charlie Hahn

Thx for the advice.
What do you mean by "the barrel should be down on the bolster"?

[Charlie Hahn]

sorry, the bolster should be down in the lock.

[melnic]

sorry, the bolster should be down in the lock.


I read an article today by Bill Curtis referenced by many others where is says the bolster should NOT touch the lock.

[John Holland]

The lock provides the physical support for the bolster. Imagine having no support under the bolster as the hammer hits the nipple with quite a few pounds of force! That condition will eventually cause the barrel to "cant" to the right as the consistent hammer blows force the bolster downwards.

[melnic]

I think I see my first bedding project is in my future.
While getting enough shim to make it so that the barrel does not rise up, the center of the barrel is making so little contact with the stock that I can bounce it about a mm or more.

[John Bly]

We use a spotting agent when inletting a barrel or parts. There is a commercial carbon black product available from Brownells or Track of the Wolf. You can also use Prussian blue or some of your wife's lipstick that she no longer uses. Mix it with oil and brush a thin coating on the barrel. Set the barrel in the stock by hand and remove it to see the spots of contact. Remove the high spots and try again. I takes multiple tries to get a good fit. Be sure to remove the spotting agent after bedding the barrel. I would suggest glass bedding it after getting it to fit better. Clean any oil from the stock with Acetone before glass bedding. Be sure not to tighten the tang screw tight when glass bedding it or you will still have the same problem.

There are two schools of thought on having the bolster contacting the lock. One claims no contact at all results in better accuracy. Others say it makes no difference if the barrel is bedded correctly. I tend to go with the latter

[Eggman]

The lock provides the physical support for the bolster. Imagine having no support under the bolster as the hammer hits the nipple with quite a few pounds of force! That condition will eventually cause the barrel to "cant" to the right as the consistent hammer blows force the bolster downwards.

Dang this is good!

[Charlie Hahn]

Maybe I did not explain as well as I should have.

The bolster contact I was referring to is in locating the barrel for bedding. Typically I like to have several hard points that align the barrel for glassing. The bolster in a correctly fitted lock plate is what I consider an important interface point. It stops the barrel fore and aft, and can help to have a correct rotation of the barrel and provide a good visual when glassing. When used as a Fixture point this provides an additional hard point to be sure the barrel to stock is cleared enough to have a sufficient bond line for the glass compound.

Regarding the issue early in the post where the barrel lifts. Using the bolster to lock is a good reference point for someone to figure out where there is a gap. how big it is and if they are comfortable in doing the repair.

The glass process is a process and it is important to not start in the middle.

I know most of us do this like a reflex having done several, as I never know the experience level it is always better to offer more detail to the discusion.

Charlie

[John Holland]

A great detailed explanation Charlie!

[WBR10654]

What you describe I think is normal, the tangs pull down in to the slot as you tighten it up and with no barrel bands to hold it in place it would cause the muzzle to rise. Every Musket I have seen the tang exerts an upwards force on the barrel. Which I always assumed was by design so the barrel was not floating.


I always put on my Barrel Bands before tightening so to make sure I do everything the same way and I was taught that I should note how the screw on the tang lined up and always put it in the same place.

I had a similar problem one day and my shots were all over the place, it turned out I had not tightened the tang screw.

One an a 1/4 turn later everything else was fine.

Next time it happened I knew what to double check and sure enough...


DPB


OK,
So I thought I was chasing a minie ball issue this past few weeks but I think I found something that is having an effect on my groups.
This week, I took my first shot and it was centered up horizontally perfect. Then shots were all over the place. After a cease fire, The next shot looked pretty good horizontally then went all over the place again.
Well, when putting the barrel back together after cleaning, I normally would tighten the tang screw up AFTER the barrel bands were put on. Last night, I tightened up the tang and noticed the muzzle rise up.
This is a Kit I build (traditions kit) and I think the barrel fit at the breach is not correct.
Just see what was going on, I stuck a piece of brass sheet past the tang to keep the barrel from rising up when tightening up the tang. 2 pics before the shim and 1 after.
How do I mark the high spot in the breech area to sand down? any tricks?
Also, are there any prefered methods to getting the barrel fit into the stock decent?

[Southron Sr.]

Bill Curtis is something of a legendary figure in the Muzzle Loaders Association of Great Britain. Their rules are very different from that of the N-SSA.

For example, the MLAGB does not allow Glass Bedding, and as even Parker-Hale replica Enfields tend to have stocks that are typically inletted oversize for barrels, about the only thing MLAGB members can do is to use shims and water pump grease to correct the oversize inletting problem on their rifles.

However, N-SSA rules allow us to Glass Bed our rifles. Glass Bedding is 1000% better than using shims and water pump grease. So get your rifle Glass Bedded. On Glass Bedded rifles, a tight tang screw produces the best accuracy.

Oh yes, the bolster of the barrel needs to firmly contact the lockplate.

[Bruce Cobb 1723V]

While hanging with some fine shooters at a range moons ago I was shooting erratic groups. One of them said let me show you something. He gently rested two fingers on top of the barrel near the muzzle and the groups immediately tightened by half!! He wasn't done. We took the barrel off, unscrewed the tang screw and then started to tighten it up again. just as the muzzle started to rise off the wood he stopped. We reassembled the bands and reshot another group, half the size of the last group! Many other things affect groups from nipples / cones to screw tightness, barrel tension etc. Magic its not.

[Jim Barber]

Before we start a skirmish, my dad always asks, "did you check your tang screw?" Humidity and temp changes cause it to tighten and loosen, you want the tension the same every time. It does make a difference, esp. in a non-glass-bedded barrel.

Cheers
Jim B.
110th OVI
Grove City OH