Rifling torque displacing POI?


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ArmedBear
July 7, 2008, 07:45 AM
I've been shooting my newly-acquired 10 1/2" barrel .44 Magnum Super Blackhawk out to 50 yards.

It wants to shoot slightly to the right, so that I had to adjust the rear sight noticeably to the left. I also noticed that when I fire it, it seems to hop slightly to the right before it recoils upward.

Can this be due to the rifling spinning the bullet, or is it something else? Or am I just imagining the whole thing?

BTW I used sandbags for sighting it in. I'm not just pulling the gun to the right when I fire it, which would of course be a whole other issue.

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Tberger688
July 7, 2008, 09:11 AM
If you want to move the POI to the right you move the rear sight to the right not left.

DMZ
July 7, 2008, 09:45 AM
Do you notice that you ease up on your grip of the gun when you use a rest?

I know I have to consciously keep the grip I normally maintain when off hand shooting, when I am use a rest, otherwise the POI well change, sometimes significantly.

Virginian
July 7, 2008, 12:30 PM
I believe what you are experiencing is torque reaction, and you are moving the sight the right way. DMZ makes a very good point about grip. I have to consciously hold on or I find myself doing the same thing.

redneckrepairs
July 7, 2008, 12:41 PM
Imho its one of two things most likely its a grip/trigger issue whereby you are " pulling " ( assuming right handed ) the gun . The other possible thing is that the frame face may not be absolutely true and when they attached the barrel it may be some fraction of a degree off the centerline of the handgun . Remember that now all companys , not just Ruger employ " assemblers " rather than gunsmiths and tho everything they mic may be in spec on assembly , tolerance stack can still bite you on the butt at times .

ArmedBear
July 7, 2008, 12:47 PM
If you want to move the POI to the right you move the rear sight to the right not left.

Why would I want to move the POI more to the right if it's already shooting to the right? Hence, I moved the sight to the left.:)

I have to consciously hold on or I find myself doing the same thing.

I tried a few different ways of gripping it, as well as offhand shooting. Also tried resting the gun in different spots (barrel, frame, grip). It did seem to have some effect, but the effect was still quite noticeably there.

My thought is to set it so that, with a "normal" grip, whatever that is, it shoots to POA. It seems that, if my grip changes POI slightly, then it may not be easy or possible to sight it in perfectly. OTOH, it really doesn't seem to be possible to wrestle the gun hard enough to stop the thing from torquing with that long barrel, so maybe it will always be pretty close.

Thanks DMZ and Virginian.

I guess my next question is, how do I best sight the gun in for field use? Do I assume that there will be X amount of torque reaction? Do I assume I will shoot offhand? How different would it be if I leaned it against a tree or something?

This is new to me, probably because I've never had a handgun that I really cared about shooting accurately past 25 yards before.:)

Thanks for any info and experiences you can relate!

Tberger688
July 7, 2008, 03:58 PM
Oops, sorry! I misread your statement I thought your were trying to move the bullets to the right.

Torque twist is something that you will notice with that gun especially with a .44 mag., but, it shouldn’t make that much difference if you do the same thing every time. How is the gun grouping, are there any cross winds, what ammo are you using, is there any lead fouling?

I have mine scoped and I get approximately 4” groups at 50 yards from a sand bag with el cheppo ammo, 240g American Eagle. It’s very difficult to sight in a revolver at 50 yards with open sights, start at 15 yards and incrementally move out to 50 yards adjusting as you move to greater distances. With all that said it is amazing what a difference a 2X scope makes for these old eyes!

It’s a great gun and I hope you enjoy yours as much as I have mine.

DMZ
July 7, 2008, 04:08 PM
I guess my next question is, how do I best sight the gun in for field use? Do I assume that there will be X amount of torque reaction? Do I assume I will shoot offhand? How different would it be if I leaned it against a tree or something?



When I was handgun hunting mule deer with a .44 Mag 7 1/2" barreled Virginian Dragoon, I would sight in and practice from a sitting position, supporting my forearms with my knees. This was the position I was most likely to assume to take a shot at anything over 25 yards. This worked for me as I hunted in heavy cover and my technique was to find a recently used trail, find a place to sit, then wait and listen.

So I would recommend you sight in based on the position you are likely to utilize in the field. And Virginian is correct about torque. That Dragoon would twist about 20 degrees before the bullet left the barrel. With heavy hunting loads I used a very firm grip.

ArmedBear
July 7, 2008, 04:37 PM
How is the gun grouping, are there any cross winds, what ammo are you using, is there any lead fouling?

Our club has an indoor 100 yard range, to help keep the local homeowners off our backs. It's also nice for shooting at night and on really hot or windy days. The challenge is that the lighting isn't anything like daylight!

There isn't any lead fouling I can see or detect when cleaning. I've shot about 85 rounds of jacketed bullets through it since I bought it used, and cleaned it twice, just to get whatever the last owner left in it, out of it. So I think I'm dealing with "just the gun" and of course with shooter-induced factors here.:)

So far, I've been able to get about 4" or 5" groups with WWB and Fiocchi rounds (240 JSP and 200 SJHP) with irons at 50 off bags. The gun seems to shoot fine; it does take a bit of practice to handle the thing. Fortunately, I used to shoot BP revolvers a fair amount, so long, heavy single actions aren't totally foreign to me, but this one is longer and heavier than most of those, and has more recoil.

Thanks again, DMZ and Tberger688.

Tberger- Did you scope a standard SBH or a Hunter model? If a regular one, how did you mount the scope?

1858
July 7, 2008, 06:23 PM
Can this be due to the rifling spinning the bullet, or is it something else? Or am I just imagining the whole thing?

Your revolver has a 1:20 RH twist so if the bullet was exerting a torque on the barrel, wouldn't it be in the LH direction i.e. causing the barrel to rotate counter-clockwise from your veiwpoint? Have you checked the grooves and lands at the muzzle for damage? I would try different loads (powder, bullets, primers) if you're reloading, or different brands/types of ammo if you're not, to get a better idea of what's going on.

The Lone Haranguer
July 7, 2008, 10:25 PM
I seriously doubt a torque reaction from the spin imparted to the bullet by the rifling is causing any problem. In a ten-inch barrel, the bullet is going to revolve perhaps half to three quarters of a turn, depending on what the rifling twist rate is. Also, assuming it is a 240-grain bullet, that is only a tiny fraction of the total weight of the revolver. There is just not enough rotating mass, over enough time duration (only a few milliseconds, the time it takes to ignite the cartridge and push the bullet down and out of the barrel), to make any difference, IMO.

Virginian
July 8, 2008, 03:04 AM
I'd suggest sighting in offhand with the additional support of leaning against a post with your left wrist (if you are right handed). I have done that in anticipation of having a tree handy when I needed it. It's worked so far.

greener
July 8, 2008, 06:46 PM
The mnemonic for sight adjustment is FORS (Front Opposite, Rear Same). If you want to go left, move the front sight right or the rear left.

Most shooting left or right seems to have more to do with grip and trigger technique than sights, assuming you have correctly aligned the sights and the target.

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