GPH problems need advice

[jbricejr]

I posted back in the spring about a loading problem I was having with a new Lyman GPH and got some good advice from folks here, which was much appreciated. However after months of working with this gun, I'm still having problems. I'm hoping to get some more advice. Here's my saga.

To deal with the tight loading problem and speed up the barrel "seasoning" process, I fire lapped the gun with a kit from Beartooth Bullets this summer. This made loading and cleaning easier and tightened my groups. However, I was still not getting the accuracy I was looking for, so I kept trying different bullets (REALs, Maxiballs, Hornady Great Plains, Buffalo Bullets, etc), and both 2F and 3F. I also dropped in a Deerslayer trigger. To back up for a minute I should note that I've been using the Lyman Receiver sight, and when I installed it back in the spring the rear screw wallowed out the wood, so I drilled out the hole and glued a dowel in and re-drilled it. This seemed to work at the time.

As I kept shooting and trying different loads I began to notice that the gun would sometimes group very nicely (several inches at 100 yards), then start throwing bullets. In a recent conversation with Jonathan Kozoil I mentioned my problem and he asked if my tang screws were tight. I checked and found that all 3 were slightly loose. I tightened them, but then found that with shooting they loosened up slightly after only a shot or two. Jonathan told me he had seen the same thing on some of his guns and that glass bedding the tang and main screw usually took care of the problem. I've been trying to get this gun ready for elk this fall and was running out of time, so I took it to a gunsmith and paid extra for a fast bedding job. When I got the gun back I noticed that there was a gap (about a mm or two) between the back of the barrel and the tang. That concerned me but the smith said the barrel and tang were butted together on the bottom. Two shots later the gap was pretty much closed, and after that the gun got much more consistent. I thought I was home free after a couple shooting sessions, but after bumping up to 100 grns of 2F I started seeing some consistency problems again, i.e. several shots grouping nicely and then flyers. Tightening the screws usually helped for a shot or two, but now my back screw on the receiver sight has wallowed out again.

I should note that the gunsmith said they glassed in a post or nut down in the stock which the main tang screw goes into. The main tang screw does seem to tighten nicely, but it loosens slightly with shooting. Here are a couple of other clues, my flyers are now all vertically aligned, i.e windage never seems to be the problem. And my barrel has always had to be squeezed down onto the stock to get the pins to go in, and the pins have to be tapped in, you can't get them in with finger pressure. Could this mean that the hook was never properly fitted to the tang, or the tang is tilted?

I'm thinking a couple things may be in order, such as: 1) glass in all 3 tang screws, 2) have an experienced muzzleloader builder check the fit of my hook to tang, and 3) consider fusing the barrel to the tang. I read somewhere that this latter idea can help a lot. Someone on this forum mentioned using solid core plumbers solder.

Thanks for any and all help guys. Fortunately I have a flintlock so I'll still be out there this week after elk, but I had really hoped to give the GPH caplock a try this year.
John

 

[stinkyfeet]

If the barrel isn't fitting the tang properly and has to be forced down into the stock then that is likely why the stock is loosen and pulling up on the screws and there pulling out of the stock. All my hawkens rifles the barrel slips into the stock smoothly and stays on its own. The wedge pins slips in with minimal effort of the fingers. I think you have alignment issues.

 

[rodwha]

My Lyman's Deerstalker needed me to loosen the tang screws so that the barrel had a snug fit with the wedge, then tighten the tang screws up. Now it fits great. Could this be your problem?

 

[rescuemike]

How long between shots? Your barrel will heat up, and that changes things a bit.. Also, have you though about a drop of thread locker to help with the tang sight screw?

Sounds like you are well on your way to having a real tack driver! See ya in the field!

 

[jbricejr]

Thanks for the input guys. 2 Tall I think you are right about the alignment of barrel and tang, with the recoil pulling up on the tang screws. I spoke with Ethan at TOW today and he agreed that the tang is probably slightly off angle. He also said that one thing that people have done is to fuse the barrel and tang with epoxy or solder, then glass bed the whole works as a unit. I've never built a muzzleloader before and am not sure I want to try to do this myself. Can anyone recommend a good muzzleloader gunsmith? It sure seems like this is a design flaw, probably to ease production and lower costs. It sounds like the better design is a tang screw that goes through the stock and into the trigger guard metal.

As many GPR's as are out there, certainly someone else has seen this problem, and I'd appreciate any insight into remedies that have proven successful. Thanks

 

[BrownBear]

...one thing that people have done is to fuse the barrel and tang with epoxy or solder, then glass bed the whole works as a unit.

A little clarification is in order.

The idea is to put a "dot" of epoxy between the tang and the breech. It's temporary, to hold it together as a unit during the glass bedding. Heck, I'd do it on a new inlet job with no glass bedding in sight.

Once the bedding job is done, you add a little heat to the dot or bead of epoxy to pop it free, so you can remove the hooked-breech barrel from the stock for cleaning, as designed. I wouldn't even consider making that joint permanent with a full epoxy job.

 

[jbricejr]

Hi Brownbear, thanks for the response. In Ethan's defense, that is exactly what he said to do, i.e. just enough epoxy to hold it together and then heat it later and break the two pieces apart. However, I have heard of target shooters permanently fusing the tang to the barrel and claiming some gains in accuracy. Some of these same folks never even remove their wedges. That may be extreme behavior, and I sure like the ease of removing the hooked breech for cleaning, but at this point I'd do anything to get this gun shooting right. It sounds like your thoughts are that additional inletting is in order prior to any more glass bedding, is that correct?

 

[BrownBear]

It sounds like your thoughts are that additional inletting is in order prior to any more glass bedding, is that correct?

The glass has to have someplace to go. So yeah, some inletting is required, but in the right places.

I prefer to bed only the back 3-4" of the barrel plus the tang. But you gotta be careful that in the process of creating more space for bedding, then adding the bedding and seating the tang/barrel you don't create a situation where the tang/barrel drop too deeply into the stock.

I learned glass bedding from an old time gunsmith when I worked for him back in the 1960's. His way is the most straight forward I've seen or tried.

Here's a quick description muzzleloader version:

Bond the tang and barrel with the dab of epoxy. Seat a small brass flathead screw in the bottom barrel flat of the stock level with the surrounding wood and about 2" ahead of the tang.

Lay the barrel/tang in place without using the tang screw/bolt and try installing the barrel wedge(s).

If they'll go in but the tang is sitting a little high, tighten the brass screw a little deeper and gently relieve the bottom of the barrel channel so the tang eventually sits at the right elevation.

If on the other hand, the tang inlet isn't deep enough and installing the wedges is a no-go, relieve the wood under the tang just enough so the wedge(s) can finally be installed.

At that point the tang/barrel should fit with the tang screws and barrel wedge(s) installed and the barrel resting on the head of that brass screw.

Now install a brass flathead screw under the tang in the middle and just flush with the wood. Remount the tang/barrel combo using the tang screws/bolt to reconfirm that it all fits.

Now you have everything lined up at just the right elevation, and it's time to make room for the glass bedding. Leave the two brass screws in place (to bear the tang/barrel) and relieve the wood about 1/8" deep in front and behind each for the distance you want bedded. Like I said- I like to do about 3-4" for the barrel and all of the tang, but clear of the tang screw/bolt.

Follow the package instructions carefully and add the glass bedding compound, then mount the tang/barrel using the tang bolt/screws and the wedges so the whole unit is pulled down flush against the brass screws. Don't get carried away with the bedding because a little goes a long ways. But don't scrimp on the release compound!

This is the easiest way I know to get everything lined up at just the right "elevation" in the stock. It's also a handy way to correct inletting that's too deep.

As a final step, be sure that the inletting behind the back of the tang leaves a little gap between the stock and the tang. Easy way to help prevent stock cracks. Conversely, having a real tight wood/metal fit back there is a dandy way to crack a stock under recoil.

 

[jbricejr]

Thanks Brownbear for the detailed response, I appreciate your taking the time to explain that procedure. I may wait till this winter to tackle this. Between work, hunting and fishing, cutting firewood, etc., the fall always goes way too fast.

 

[BrownBear]

...wait till this winter....

Oh yeah.

 

back in the days of carburetor tuning we had a rule of thumb. Only change one thing at a time.
Else you wouldn't know which change made it better or worse.
Over the years I've heard and seen a lot of folks glass bedding their stocks.
Never done it myself never needed too.
Provided your stock is not inletted too deep in the first place, normally all you need to do to get a proper fit, is carbon paper and a scraper blade for wood (like a drawbar knife) but shaped like a screwdriver or chisel.
Lay the paper in the stock carbon side down, insert barrel and pin,some very light taps with a rubber tapping mallet.
Remove barrel and paper. Carbon marks indicate where the barrel and stock are pinched.
Lightly scrape and repeat until no carbon marks.
Look fibre glass etc, did not exist back in the 1800's.
After 1 or 2 scraping sessions. Assemble the barrel. Go shoot it, see if better. Then decide if you need to scrape again.
None of my rifles use pins, mine are all flat wedges.

 

[Billnpatti]

You have been given excellent advice on how to work on the problems with your rifle. Once you have them solved, you will need to address how to wring the maximum accuracy from your rifle. Take a bit of good advice and go to this website http://www.blackpowderrifleaccuracy.com/ and order one of Dutch's accuracy systems. It will at first glance seem to be only a few sheets of information. but, as you read it, you will discover that it contains more directly useful information in a logical process than most any tome that has been published on the subject. It is well worth the $20 that it costs. In reality, it is the best bargain that you can buy for $20 for muzzleloading. It will become a muzzleloading accuracy bible for you.