2 groups? Weird...

[Black Jaque Janaviac]

I took out a little Cabela's .50 carbine to see if I could find a nice roundball load. I don't think Cabela's carries this gun anymore, but it is one with a fast twist 1:24", I think.

Figuring the twist rate is comparable to many roundball pistols of similar caliber, I thought it might do well with a pistol charge.

So I tried 45 grains of FFFg. As I shot I noticed something strange. There was an upper group and a lower group. Taken individually the groups would be excellent; just under an inch at 33 yards. However taken as a whole, the distance between groups was more like 3 inches. It seemed to be divided equally with about 1/2 the shots high and half low.

I tried 45 grains of FFg too and it did the same thing.
*Swabbed 'tween each shot.
*Shots were rested. I sat on a short stool and rested my elbows on my knees.
*Consistantly sunny day. No clouds.
*#40 cotton drill tight fit.
*.490 ball
*sights are fixed, no adjustment unless you drift or file something.

Thoughts?

 

[Jay Dobro]

Just my feelings, Barrel lengths with the same caliber and twist may make a difference.

 

[Tom Compton]

I'd say you are near 40. That's when many of us start getting a ghost around the rear sight. Then sometimes we level the front sight on the ghost raising the poi.
TC

 

[Walks with fire]

Might try a .495 ball or a thicker pillow tick patch. A 1/28 twist .50 I have does great all the way up to 90 grains. Isn't supposed to but it does. I use a .495 ball with .016 red stripe wally world pillow tick and Hoppe's #9 patch lube. One big hole at 50 yards.

 

[Black Jaque Janaviac]

40 Flint,

Yep. I'm 45. I'll have to pay more attention to the sight picture.

 

[Black Jaque Janaviac]

Martin,

I'm sure barrel length will have some effect. But I can't imagine it would cause 2 groups to print.

Like I said, if you take the groups individually they are satisfactorily small. It is only as a whole that the two groups are far apart that it looks problematic.

Keep in mind - I did not work up or down the powder measure to see if 50 or 55 grains worked better, or maybe 40 or 35 grains.

I just thought it strange that, when I shot 3 shots two shots were on top of each other, the third one was low. The next 3 shots: two went by the previous low "flier", and 1 shot went high up by the other two.

I drifted the sights for windage, fired three more shots and again, two went low one went high - exactly on the same levels as the other 6 shots.

 

[SgtErv]

Was wondering if you could clarify what the ghost is? Vision related issue that comes with age? I get a real strange fuzziness trying to focus too hard sometimes

 

[biliff]

I've had that happen with open sights when the light keeps changing (i.e. rapid shifts between clouds and sun). Plays hob with a consistent sight picture. Not sure what's going on in your situation.

 

[coloradoclyde]

The shorter the sight radius the more sighting inaccuracies will be exaggerated.....
Does the gun fit you well?
I would also try different powder charges
to rule that out.
Having someone else shoot a couple groups will also rule you as the cause out.

Sometimes we just need to "get to know " a gun.....

 

[Grenadier1758]

Up and down sort of tells me that something is changing with your front sight. I am assuming that your sights are not moving, but check the rear sight anyway.

Let's try a shader to shade the front sight. Get core from a roll of toilet paper. Slit it lengthwise. Set it on your barrel to shade the front sight. You should be wearing safety glasses so you can punch a hole in a small square of black electrical tape. Place the tape on your glass to create a pinhole sight. That should sharpen your sight picture.

 

[mooman76]

How large is your target? It should be small as you can still see well. Aim small, miss small.

 

[necchi]

I had one of those, for about a month.
I could not get it to pattern at 50yrds with Ball or minnie or maxi no matter what I tried.
I took the gun back.
Cabelas was a little bucky about it until I told them I'd take the money back in trade,(card).
It might shoot the plastic things, never tried.

 

[excess650]

I HAD a TC WMC with short barrel and even quicker twist. Only ONCE did I get it to shoot a decent 50 yard group with PRBs, and I couldn't repeat it. It shot Lee 250gr REALs pretty well.

My TC Grey Hawk (24" 1-48).50 was never a stellar PRB shooter either, regardless of ball, patch or powder charge. It shoots those unmentionables like a laser. I managed to buy a pristine .54 GH barrel and it shot PRBs superbly from the getgo.

 

[Black Jaque Janaviac]

I know what yous guys mean. I had one of these same guns in .54 and couldn't get it to shoot a consistant group to save my life.

If a gun is shooting poorly it would seem like it would make one, big group. Or one group strung out in a long line.

But to shoot a high group and a low group seems like a tease. Almost as if the gun is telling me it will shoot roundballs really well if I just figure out the one thing . . .

 

[Rifleman1776]

As mentioned, sight picture and/or wiggly sights might be the cause.
Whatever, to have a proper group you must have sufficient pressure. My guess from here is your charges are too small. My gut is telling me your grouping will improve at about 50 grains of real black powder.

 

[Tom Compton]

When the rear sight is out of focus we see the blur. The actual rear sight is darker and there is a blurred second image around the darker actual rear sight. I call it a ghost but it could be called many other things. When concentrating on the front sight we sometimes hold the front sight high levelel with the ghost of the rear sight then other times level with the actual sight. It's like raising and lowering the rear sight.

I was 42 when I first ran in to it. A call to my friend master gunsmith, master stock maker, and world record setting rifleman Tom Gillman, he immediately explained it. A couple of days later on the range I SAW what he described and what I'm attempting to describe.

Remedies range from a Merit Optical Disc or other peep apparatus to installing actual peep sights to moving the rear sight further from the eye. I have an original barrel with 2 plugged rear sight dovetails and one vacant as the owner(s) adjusted to their changing eyesight.
TC

 

[SgtErv]

That is fascinating...thanks for the explanation. I'm going to pay more attention now.

Might very well explain OP's mystery groups.

Learn something every day here. Thank ya sir

 

[excess650]

I've seen original rifles with a 2nd dovetail, and apparently not because the barrel had been re-breeched.

One of my flintlocks has the barrel dovetail vacant, and a rear sight inlet into the tang. It works much like a peep despite the square bottomed notch.

 

[wulf]

Try weighing the balls. You may have two different
weights eventho the dia is the same...

 

[jethro224]

Is the tang seated well in the stock? Does the hook breech engage tightly with no shifting?
Only thing I can think of is something is moving around.