Unpredictable patterning

I have a custom built Lancaster county rifle. It always shoots tight groups however some days I go to shoot and it’s a foot off of where it last was. It still patterns tight but I’ve never had a muzzleloader do this. What do you guys think is going on. I load it the same every time 75 grains FFFg goex black powder, pillow ticking patch and .490 roundball.

Something is happening that is moving the sights or the sight alignment..

What happens between shooting sessions? Describe the cleaning process in detail.

When cleaning is anything done that might indicate loose sights?

Is the barrel removed and reinstalled? A Lancaster should be pinned and the barrel shouldn't have moved.

Grenadier1758 said:

Something is happening that is moving the sights or the sight alignment..

What happens between shooting sessions? Describe the cleaning process in detail.

When cleaning is anything done that might indicate loose sights?

Is the barrel removed and reinstalled? A Lancaster should be pinned and the barrel shouldn't have moved.

Click to expand...

I clean the same way every time I use hot soapy water Ana a jag I make sure that it is cleaned properly with a small bore light to then I put bore butter on a patch and grease the barrel and other metal parts for storage. I dry the barrel before shooting by running a couple dry patches on a jag. The gun has always shot well and this problem has only recently started since I moved from the Detroit area to the Houston area. My other guns have no issue from my .32 to my tradeguns. It seems to be specific to this gun. The bore is in excellent condition so I’m scratching my head trying to figure this out. It likes to be spit patched every 5 rounds or so to maintain accuracy at the range.

Does the rifling look sharp inside the bore?

I do not have any experience with the “new” Bore Butter....
But I had my share and then some with it in the 70’s...

From your description of your cleaning routine, I would think the issue could be with the bore butter remaining in the rifling.

I’m not sure of the consistency of the “new” stuff, but there is no way a couple cleaning patches would have gotten all the bore butter out of the rifling.. with the old stuff.

My gun then, acted almost exactly as you described.

Eventually they got too where the first shot or two would be close too the point of aim, then they were all over the place.

Disregard.... I re read your post , you said your gun is a foot off, but still holds a good group.

How many different times has this happened?

smo said:

Does the rifling look sharp inside the bore?

I do not have any experience with the “new” Bore Butter....
But I had my share and then some with it in the 70’s...

From your description of your cleaning routine, I would think the issue could be with the bore butter remaining in the rifling.

I’m not sure of the consistency of the “new” stuff, but there is no way a couple cleaning patches would have gotten all the bore butter out of the rifling.. with the old stuff.

My gun then, acted almost exactly as you described.

Eventually they got too where the first shot or two would be close too the point of aim, then they were all over the place.

Disregard.... I re read your post , you said your gun is a foot off, but still holds a good group.

How many different times has this happened?

Click to expand...

I guess it could be that. Though I’ve not had that problem before. As for the rifling the only difference between this and my other rifles is that this gun has button rifling but it is smooth as the barrel has been hand lapped by the builder. I will make another trip to see if maybe you’re on to something. Should I maybe switch to a thinner oil. Could just use olive oil on a patch as it is thinner. Just a thought though.

Try ditching the bore butter. I have a rifle that I sighted in during the warm weather using bore butter as patch lube. Went hunting in the cold weather and shot right under a deer. Test fired and found it hit a foot lower in the cold weather.

Ditch the bore butter. Final protection would be better if you used Barricade.
Its also a lot warmer in Houston. Try spit patches for every shot as the lube. Worked wonders for my groups and a lot less mess to swab out afterwards.

My thought is you have wood movement putting pressure on your barrel.

Ah, you have added a change in environment with the move from Detroit to Houston. Poker brings up a good observation in that there might be wood movement.

Time to take your custom built Lancaster rifle apart by removing the barrel from the stock. Get a good wax, such as Johnson's Paste Wax, to wax the barrel and the barrel channel in your stock. Look at your under lugs. They need a slight elongation to allow for the change in temperature and humidity. Wood moves with changes in temperature and humidity more than the barrel. The barrel moves with changes in temperature. All these movements will change the barrel harmonics and will move the impact on the target. The holes for the pins in the underlugs need to be elongated parallel to the barrel. Get a small needle file and elongate the holes. It doesn't take much.

Use an alcohol dampened patch to remove the bore butter or better yet, use Barricade as the long term rust inhibiting lubricate. Still use rubbing alcohol to remove oils before shooting your rifle.

Are the underlugs slotted?

Lot of good information here thanks guys. A buddy of mine in Michigan mentioned slotting but not sure I understand how to do this

Slotting or elongating the underlug pin holes, same end result.

Slotting or elongating is done the same way. Remove the barrel from the stock, use a small needle file that fits in the pin hole in the underlug and file an elongated hole parallel to the barrel.

I’m a newbie but when this happened it was that the sights were either Loose(front sight)
Or out of alignment some how

hope you find the answer

My rifle did this same thing for the first time this summer and Fall. Never happened before, always perfectly accurate. Suddenly it was shooting all over the place, wild shots. At the recommendation of the barrel maker, and under the guidance of a local senior rifle maker, I dismantled the gun. Used a correct diameter punch to remove the pins, carefully removed screws, bolts etc. What I found was surprising to me but not surprising to my guides on this. The man who "made" this gun for me was new to gunmaking, and oversold his skills. He had made some egregious mistakes when I picked it up years ago, so bad the gun would not even fire, and I had to have another, more senior maker re-weld parts back onto the lock etc etc. So what we discovered in the barrel channel were proud backs of the ramrod pipes. These were not level with the bottom of the wooden stock channel, but stuck up and touched the bottom of the barrel. Other proud metal pieces also existed throughout the length of the barrel. Every one of these proud points was putting pressure on the swamped barrel, which is actually very easy to bend, even by hand. When the barrel bends or experiences pressure, even slightly, there goes the accuracy. So several round files were used to remove all of the proud bits in the channel, and small flat files were used elsewhere to eliminate those other pressure points. Additionally, the pin holes were slotted so that the barrel can move a little bit. High-tension pins are just like any other pressure point. I am the least mechanically competent man you will meet, and I felt like a certified gunsmith after this process. It took me several passes to get everything absolutely level, plumb, aligned evenly, and ready for prime time. But it then shot correctly. Your move from Michigan to Texas FOR SURE altered the stock wood and its relationship to the barrel. Good luck and have fun

Several diagnoses have been made and any one of them could be the cause of your problem. I'll just mention a similar problem I once had.

Years ago my .40, of known fine accuracy, started doing the same thing you posted. It would shoot spectacularly one day but not the next. It didn't take me long to notice the rear sight could be wiggled around using a finger and thumb. A bit of peening to tighten it stopped that nonsense. Now I'm the only accuracy problem.