625-6 Mountain Gun sights

[Acroyer]

Hi guys. I have been to the range several times with my 625, and it seems I can't hit a thing. Not long ago, I bought one of those universal bore sights, which can be used on about anything from a 22 to a 12 gauge. Using that, I easily fixed the windage. Elevation was another thing altogether. I knew I was shooting low, and that's what the laser showed. I was watching the dot and sight alignment start to come together, and raised the rear sight WAY up. All the way up, it turns out. And yes, I dropped the rear sight elevation stud, somewhere...

I figured that couldn't be right, so I order a new stud and a cartridge style bore sight. Oh, this is 45 Colt, btw, forgot to mention that.

Anyway, I reassembled to rear sight, popped in the laser and the dot showed the same darn thing.

Now, it's really, really off. I am talking the dot shows about 4 inches lower than point of aim and about 10 ft. It just gets worse as it goes out, of course.

I'm not sure of the best approach to solving this issue. The front sight is pinned, so I guess it could be replaced, probably by a smith, since I don't have the punches or drill bits for something like that. Then, I am thinking if I am going to get rid of the stock sight, why don't I just file it down like on old single actions?

It's not an emergency, so I am not going to jump right into anything. I wanted to get some opinions or ideas before I did anything drastic.

Tony

 

[StrawHat]

First question, what ammunition did you use to sight it in?

What range?

I have a similar Mountain Gun but in 45 ACP. It like standard 230 grain bullets at about 870 fps. I can sight it in with slightly heavier loads but stick with the standards.

Oh, I sight in initially at 25 yards.

Kevin

 

[MikeR90S]

In my experience the elevation is very bullet weight sensitive with big bore guns, and can't really be bore sighted. 185 gr is going to impact low and 230 high for the same sighting, but both will be in the range of adjustment for the stock sight height.

 

[DR505]

That is odd...my .45 Colt 625-7 MG seems to like 250-270 grain bullets at roughly 900 fps. I still have plenty of elevation left for the rear sight. They seem POA/POI at 25 yards.

 

[Protocall_Design]

I have seen a few guns over the years that had the threads in the frame slightly off in various directions. You can't sight one of those in because the sights don't go that far. The further from the gun, the worse it's off. Maybe you got one of those? Hard to say without looking at the gun, but I would lay a straightedge on the top of the frame and see if the barrel falls away from it towards the muzzle.

 

[Mike SC Hunter]

That is odd...my .45 Colt 625-7 MG seems to like 250-270 grain bullets at roughly 900 fps. I still have plenty of elevation left for the rear sight. They seem POA/POI at 25 yards.

Mine too. My std. load is my cast 250 gr SWC pushe4d by 8.5 grs. of Unique.

 

[Acroyer]

Thanks for the responses. I have been using handloads, 255gr slug over 9.5gr of Unique. Range shooting has been at about 7 yards, out to 15 yards sometimes. The same load is spot on using my Ruger Blackhawk. maybe I just need to find the right combo for my 625? Kind of expensive, but I might end up getting several different factory cartridges to find out what it really likes. I'd rather not do any modifications if I don't need to.

Thanks for all of the input.

 

[ms]

My 625-6 MG shoots an inch or two above point of aim at 25 yards with my plinking load, 255 SWC at about 760 fps. I just checked it with a boresighter, at 10 yards the dot is about 8" below point of aim.

 

[jcelect]

The OP is using a "bore sight" which aligns the bore with the target, not the sights. The sights must be adjusted to the red dot. Install a taller rear sight blade!

Hey MikeR90S
"185 gr is going to impact low and 230 high for the same sighting," Because the 230 gr travels down the bore slower, the barrel is higher in the recoil arc when the bullet exists the barrel, so the bullet strikes higher.
jcelect

 

[ms]

Not quite...

The OP is using a "bore sight" which aligns the bore with the target, not the sights. The sights must be adjusted to the red dot. Install a taller rear sight blade!

Hey MikeR90S
"185 gr is going to impact low and 230 high for the same sighting," Because the 230 gr travels down the bore slower, the barrel is higher in the recoil arc when the bullet exists the barrel, so the bullet strikes higher.
jcelect

The revolver's muzzle will flip up while the bullet is in it. The sights need to aim where the bullet will go at the range you want, not to the bore axis. You make this point in the second part of your post.

 

[kbfire]

My 629 Mountain Gun sights

I replaced the original sights with the C&S extreme duty rear and a SDM 14k gold bead front sight. Works well with my older eyes.