Rifling depth and accuracy?

[4-Liberty]

I've been trying to pattern my 54 cal. 1803 Harpers Ferry for some time now. I bought this rifle back in 2006 from Dixie, and it has very shallow rifling. The rifle is fairly accurate for about the first 6-9 shot (first 3 are usually touching at 50 paces), and after that, I am all over the paper. I run a wet patch and a dry patch after each shot. I'm shooting a 53 cal patched round ball with .010 prelubed patch over 95 gr. 2F. I'm thinking that since the rifling is so shallow, any fouling that does occur might be enough to prevent the already shallow rifling to grab the patch, in spite of it being swabbed between shots. It's a 1:66 twist, so I  don't think it's suitable for a conical or maxi-ball. I'm kinda stuck.  I guess my question is, is this typical? Has anyone else had experience in this?
Any suggestions are appriciated.

[prairie dog]

Are you shooting from a bench rest?

[4-Liberty]

Yup! I'm using a lead-slead.

[prairie dog]

Good, that takes you out of the equation.  Your results sound like the problem I was having with my Lyman GPR (which has fairly deep rifling). It would shoot a few rounds into tight groups and then land shots all over the paper.

 A long and drawn out load development process proved this rifle wanted a very tight load, 495 ball with a heavy denim patch, and it didn't like any grease based patch lube.  Spit, moose milk or water/Ballistol on the patches shoot very well.  It shot better still when wiped once with a slightly damp patch between shots.  

It sounds like your rifle wants to shoot but just doesn't like something you are feeding it.  

Not the answer you were looking for, but a through load work up will show you what the rifle needs to shoot it's best.  Sounds like you have a finicky rifle and I'd bet that once you discover what it wants to shoot it will impress you.

[Hank in WV]

Some sound info there. If that doesn't work, you might want to take the barrel out and look at the lugs underneath to see if they're slotted or not. If not the barrel may be expanding and the stock is pulling it every which way.

[4-Liberty]

I did work up a load, but there are many more variables that I have yet to work through. I've only worked through different patch thicknesses (0.010, 0.015, 0.018) and charges of 2F, with the same ball size and patch lube. I suppose I might just have to work through differnt variables of lubricants and try how she likes 3F.

[prairie dog]

Did you try .530 and .535 balls?

[4-Liberty]

No, unfortunately I didn't. I bought a mold for it before I knew about the process of working up a load.  

[Fletcher]

I have found that shallow rifling does not grip the patch as well and does
get worse faster with fouling. A thick patch may actually slip worse. I believe
that the bigger ball with the .010 patch would hold tighter, even with some fouling.
I think I have several.535 molds and don't shoot .54 that often (just traded my
T/C .54 for Pacific Yew staves  

[4-Liberty]

Fletcher, I have a feeling that is that case just by how it did threw the pattern the longer I shot as I was working up my load. I'd like to make a trade but unfortunately I don't really have too much that I can trade. This is still a relatively new hobby for me, so what I do have, I use. Maybe sometime in the future. I plan on using it for this years deer season. I know that my first shot or two are dead on at 75 paces as long as the barrel is cleaned well and ungreased. I'd just like to have it be able to last a long shooting session without having to pack it in early because it is shooting all over the paper. This might be the last season I hunt with it anyways because I might sell it to buy kit to build after my Lancaster Longrifle build is finished. But that is yeat to be seen.  

[Riley/MN]

If it is jumping/slipping the rifling, you may want to try a lighter powder load. 95 gr is plenty. Not sure where you started your load work-up, but I like to work up from ~ a grain per caliber. So in your case start at around 55 gr, work up in 5 gr increments. You may find a "sweet spot" that uses a lesser charge.

[Bigsmoke]

Good advice there from Riley.  FWIW, on the occasions I shoot a .54, I typically use an 85 grain charge of Ffg.
If you are having issues with fouling, I have found that separating the powder charge from the PRB with a lubed shotgun cushion wad works wonders.  When you load the wad it does two things, it first pushes whatever fouling is in the barrel down with it, and also lubricates the bore to help keep the fouling from the next shot softer.  As I recall, a 28 gauge wad works pretty good in a .54.
When I had my .72 cal rifle, I was running 200 grain charges in a barrel that had rifling about .006 deep.  Using a 12 gauge cushion wad I could fire as many shots as I wanted to without cleaning and they all loaded easily and shot well.
John

[Rocklock]

Yep I'd try tighter ball and patch w 50 gr FF. Tighter load should grip better, lighter load will accelerate slower less likely to strip and FF will soften acceleration too.
TC

[mossie]

My TC PA Hunter barrel behaved just like yours does and it took me a long time to get it to group good after 5 or 6 shots even if I wiped after every shot. The first shot was always very accurate as were the next couple of shots.

Eventually I started using a wire bore brush small enough to reach down in the patent breech area because I knew it liked a clean bore. I use a cleaning patch wrapped around the brush and swab out the patent breech every 3 shots or so and run a dry patch in there after that. No more problems with the rifle throwing a flier. It's a wonderfully accurate rifle but I doesn't tolerate being real dirty. It also doesn't like 3f nearly as well as 2f Goex.

I have no clue why it doesn't like the fouling in the patent breech and it wasn't delayed ignition either but it doesn't like any fouling in there. I named the rifle Eureka.