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12 guage TC Black mountain magnum shoots low

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bigbore442001

50 Cal.
Joined
Nov 25, 2004
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A while back I purchased a previously owned but never fired Thompson Center Black Mountain magnum 12 gauge shotgun with screw in chokes. I have been playing with it as of late and one thing that bugs me is that it patterns low.

I was patterning on a turkey head target at 25 yards with 100 grains of H777 and 1 3/4 oz of no 6 shot. I placed two felt wads between powder and shot and one over the shot.

If I aim the gun like a rifle with the bead level with the tang( bear in mind most turkey hunters aim their shotguns rather than point as if it were a pheasant being flushed) the pattern is low. If I point the bead well above the tang the pattern is more centered. I know the obvious action is to aim it in that manner but for me it is a little discerning. I would rather aim with the little U notch in the tang for turkey hunting. This gun is going to be used mainly for turkey rather than upland game.

Could I shim the forestock to raise the muzzle? I am not sure if that would work but I will defer to those people with much greater wisdom than I. Thanks
 
BB..any chance of replacing the bead with a smaller one..had to do this on a 12 ga. new Englander barrel brought the POI up 6 to 8" at 30 yards..or else use the bottom of the existing bead as your focus point. Your other option is to put the bottom of the bead at the top of the turkeys head.
 
bigbore442001 said:
This gun is going to be used mainly for turkey rather than upland game.
If it was me I'd either add a rear sight to be able to raise / adjust the POI;
Or, have the barrel straightened to correct the POI;
 
BB One other idea..add a short raised solid rib on the top of the tang ahead of the top screw.
Solid no notch.just thinking out loud...Dan
 
I am glad to see that there is no end to the jocularity here. :thumbsup:

My fear is that subconciously at the last miute I will compensate and put the bead in line with the tang and fire with the result of a crippling body shot instead of a clean killing head-neck shot.
 
bigbore442001 said:
My fear is that subconciously at the last miute I will compensate and put the bead in line with the tang and fire with the result of a crippling body shot instead of a clean killing head-neck shot.

On a serious note, I completely agree...you have to get it right...the old "react like you train" syndrome will kick in on game, and you'll align the sights like you have all your life

I had a new .50cal T/C round ball barrel that would not shoot to center axis of the bore, and sent it back to them...they have a laser guided barrel alignment machine to fine tune align (bend) barrels...I assume they could do that smoothbore barrel as well...might give the service manager a call.
 
After this season I plan to send it back. Here are some pictures of the gun and a pattern taken at 30 yards.

TCBlackMountainMagnumandpattern.jpg


TCBMM30yardpattern.jpg
 
BB... Do yourself a big favor and get big sheets of white paper or white card board..bench the gun and pattern..shooting at a 8.5X11" sheet of paper only gives you part of the big picture.

Minimum 30" X30" apply a center target..pattern and then report back .
You need to see the whole picture.
 
I am not familiar with this gun, but can you use the tang bolt to hold a homemade rear sight as needed?
 
Bigbore,
This months Muzzleloader Mag (May/June issue) has an article on a rear peep sight that mounts on the tang for hunting. The sight is adjustable for elevation and is quite simple to make.
PM me with your email.
Dusty
 
Dusty,
I'm not bigbore but I PMed you too, I would like to see that sight. Hard to get magazines over here, I live in South Korea. Chris
 
Never done this with a muzzleloader, but I did have to modify the bead on a NEF single barrel. I carefully filed it down a bit at a time, then on one side to move my point of impact where I wanted it. I had to do the same thing on a Mossberg 835 once to shift the pattern to the right. Worked beautifully and it was utterly necessary with that extra-full turkey choke.

I personally would try this before I'd send the gun back.
 
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