Point of impact issues

[robescc]

Hello gents. Yesterday I shot my Knight MK85 in .54 cal for the first time. It’s a Rocky Mountain elk foundation model made in 1993 and yesterday was the first time it was fired. I put William’s globe sights on it.
I got it zeroed at 50 yards and was shooting 1” groups with 100 grains of FF Triple Seven and 348 gr Power Belts. The issue started when I went to 100 yards. I was consistently shooting 20 to 24” low. This makes absolutely no sense to me as I should have only been a couple of inches low. I also tried 120 grains of powder and didn’t move the point of impact much. I then switched to some 250 grain saboted bullets and the point if impact was no different.
What in the world could be the issue?

[robescc]

No advice at all?

[Blacktail Sniper]

Maybe the twist rate in the barrel is not good for that projectile? 

[birddogdad]

the math makes no sense.. that is where you should be at about 300 yds not 100.   

are you certain that the poa is not off? i know its a stretch idk if everything you toss is there (2' low) ...

[Bob33]

That doesn't sound logical at all. Can you shoot at distances between 50 and 100 yards to see what happens?

[2MANY]

Loose Sight

[robescc]

That doesn't sound logical at all. Can you shoot at distances between 50 and 100 yards to see what happens?

I'd have to go to a pit somewhere.

[robescc]

Loose Sight

I used loctite on all the screws. I can go back to 50 yards and I'm in the bullseye. It's not loose sights, I ruled that out.

[callturner]

So, you got it on paper now. Adjust your sights to hit at 100. You can see where you're hitting at 50 afterwards.

[Bob33]

The only explanation from a ballistics perspective is that you have very slow velocities in the neighborhood of 700 ft/second. If you have access to a chronograph you could verify that.

[HntnFsh]

Are you fudging on your sight picture so you can see the bullseye?

If so that could account for part of the problem.

[buckfvr]

Twist rate not compatible with projectiles?    Is that rifle designed for round ball which would have a much slower twist and not be suitable for modern muzzleloader projectiles.....Just a thought.

[buckfvr]

Maybe the twist rate in the barrel is not good for that projectile?

 

[ghosthunter]

If you need to barrow a chronograph,I have one and am close by.

[bkaech]

Another thought is bad powder making low velocities, but that would likely make everything inconsistent so not likely. Are you measuring your powder wrong? A problem with your powder measuring might mean you are only loading 50grains???  I'm just spit balling here....

[BUTTER]

How many shots between cleanings?

[BUTTER]

Other food for thought. When I bought my original knight from the store brand new I looked down the barrel and there was already rust forming olin the barrel prior to ever being shot. Did you happen to look in the barrel before you shot the gun and or have you thoroughly cleaned it

[birddogdad]

The only explanation from a ballistics perspective is that you have very slow velocities in the neighborhood of 700 ft/second. If you have access to a chronograph you could verify that.

  if its not that slow you can really rule out ballistics or bullet issues, the math doesnt lie!  get a speed exiting the barrel, if this slow, you have powder issues ( i would guess). if 2-3X this , it isnt the bullet or powder , look for aim issues.. ie lose site, bad aim, you.. ect....

just throwing out there, are you using the correct caliber bullets?

[robescc]

Thanks all for the input. I am going to shoot through my chronograph today. I have three lbs of powder so will test each one.

I am using these sights with the fine crosshairs and my aiming point is at center of target

I will also add that I am a very experienced shoot, even with a ML, so I don’t believe form is an issue. I use to compete in long range competitions.

[OutHouse]

I second the idea that the speed of the bullet may be too slow. I have a cut down .54 caliber Hawkin that also does that at greater distances. Great for 50-75 yard shots but dips a lot after that. I use it in real thick woods so its not an issue yet anyway. It killed one deer so the bullet is fast enough I suppose.

[robescc]

I figured it out. It was definitely a bullet issue. My rifle did not like those power belts at all. I’m now shooting 2 inch groups in the bull’s-eye at 100 yards.

[huntnfmly]

Thanks for the update glad you got it figured out