POI Corrections on Potsdam Musket

[oscarlovel]

I shoot smoothbore competition in the N-SSA. Normally I shoot my ArmiSport 1842 and do well with it, but I also have an original Potsdam Musket Conversion in .72 caliber. I have fired it and it shoots a very nice group with a bare .715 ball and 60 grains of Swiss 2fg. The ball is double coated in my minie ball lube (beeswax/olive oil). Offhand I can hold a consistent two to two and a half inch group at 25 yards. Problem is my point of impact is about 7 inches right of my point of aim at that distance. The Potsdam has a rear sight  on the tang and the front sight is on the front barrel band. In the N-SSA we are not allowed to make any alterations to the sights, so that is out. The previous owner suggested that I bend the barrel. I have purchased the parts to make a jig for doing so. I have held off because I'm dealing with a 190 year old soft iron barrel. Frankly, I don't want to screw it up. The previous owner also had the muzzle re-crowned professionally by Dan Whitacre. I was reading somewhere online that with a smoothbore, you can alter the point of impact by  judicious removal of material at the inside of the muzzle. Can't remember now where I saw that, but if true, can someone please expound upon this process? Would appreciate any opinions from the experts here on which would be the best avenue to pursue to bring the POA to the POI. Thanks!

[sse]

While not something I have knowledge of...a most interesting question.

[Stormrider51]

Oscar,
There are several ways to deal with your problem.  The simplest is to try changing your face placement on the stock.  I note that you say there is a rear sight on the tang.  I'm assuming it is not dovetailed and can't be drifted?  Can you open the aperture by filing the left side of the groove?  This will move shots to the left.  Can you remove the rear sight and rely on face placement?  Given that you have an original gun I'm hesitant to suggest anything more but there are options.  Filing the muzzle will work but if you are 7" off at only 25 yards it's going to take some filing.  Better would be barrel bending but I'd suggest you take the gun to a competent gunsmith who is experienced at doing this sort of thing.  I had a customer bring me a single barreled shotgun that he had used as a club to kill a raccoon.  The degree of bend in the barrel was visible when sighting down it.  I used lead support blocks and a hydraulic press to gradually straighten the barrel until it shot where it looked.  It took time and repeated trips to the shooting range.  In the case of your Potsdam a single dent in the barrel while pressing it would ruin the value and possibly make the gun unsafe to fire.  The choice is up to you.

Storm

[oscarlovel]

Yeah. The problem is that by N-SSA rules, you cannot alter the front nor rear sight at all, nor can you remove the rear sight. What I am wondering is if the POI/POA was fine before the previous owner had the muzzle recrowned? I can see no apparent bends in the barrel. I may just have to set it aside and finish my rebuild on my other Potsdam, which I am restoring to military configuration after a post CW sporterizing. Stock was cut off just in front of rear barrel band, front sight soldered on with a poor installation of a ramrod thimble. The barrel was deeply pitted inside the bore, so I sent the barrel to Dan WHitacre who was able to save the breech section and graft a new .69 cal barrel onto it. This is legal for N-SSA. I guess I just like lobbing those 0.715 balls downrange. I may have to be satisfied with using them in my Brown Bess instead.

[Stormrider51]

Hopefully someone will come up with a better answer than those I offered.  The fact that you see no bends in the barrel isn't proof that they aren't there.  The last inch or so of bore is what matters.  It's how the bullet is released into free-flight that counts.  I've seen modern Remington 700 barrels where the bore wandered enough to make me question how the rifle ever fired accurately and yet it did.  If you want to take a chance lock the barrel upright in a vise with the front sight facing you and file the muzzle while tilting the file slightly to the left.  Make a few file strokes and go shoot the gun.  It can be a long process but it works.

Storm

[mario]

So N-SSA rules essentially prohibit you from actually sighting in your gun?

Mario

[oscarlovel]

That's the gist of it. Idea is that other smoothbores mostly didn't have a rear sight. The rule is probably intended to level the playing field.

[Kermit]

Or make it equally convoluted and bumpy?

[Geezer in NH]

Sight it in then refinish to look like it not been. Easy to do Many here will not like this answer but NSSA are idiots IMHO

[rose]

You cannot alter the front nor rear sight at all, nor can you remove the rear sight. What I am wondering is if the POI/POA was fine before the previous owner had the muzzle recrowned?