Rossi 44 mag vertical stringing

[HPT]

For some time now, I've been seeing consistant vertical stringing with my .44 mag Rossi Puma 92 which is the model with the crescent buttplate. Basically all 10 shot groups are 2" or less wide but up to 6 or 7" vertical.

The barrel has been slugged at .431 dia and 2 molds were ordered at .432 dia - one making a 215 grain plain base bullet & the other a 265 grain plain base bullet. These have been tried using 20:1 alloy and wheelweights. Several powders ave been tried including swiss blackpowder, IMR 4227, Li'l gun & pistol powder in velocities ranging from 1,000 to 1410 fps loaded with or without wads or powdered plastic. Also tried were 240 gr XTP and also 300 gr gas check bullets. Doesn't seem to matter what load almost all groups have the vertical stringing - so I don't think it is ammo

Two shooters have shot the gun - me and a friend (he shoots min 50 rounds a day everyday from some type of gun) and we got the same results - so I don't think its the shooter

So (in my mind) that only leaves the gun. I can only think that the next step would be to remove the forestock magazine etc until only the barrel & action remain and see if the problem goes away.

Anyone else experience vertical stringing with a levergun & have advice on things to try to fix it?

[Larry Gibson]

The vertical stringing can be causes by too much tension the mag tube plug screw agains the barrel and/or too much spring tension if you are loading multiple cartridges in the magazine to shoot the test string(?).

You might try reducing the tension the screw puts on the barrel and shortening the mag spring to about 4" of spring sticking out of the end with the magazine empty of cartridges. Both eleiminated the vertical stringing in my Rossi 24" barreled .45 Colt rifle. Those are also some of the cures for vertical stringing in othet leverguns also.

Larry Gibson

[HPT]

Thanks Larry,

Is your gun the type without barrel bands? I'm guessing the screw you mean is the one that goes thru the tube? I'll start there and if it still happens, continue to look for tension issues.

[runfiverun]

i'd bet on the mag tube.
the forend can be the issue too.
and if you are shooting off a front rest,move it back to as close to the frame as possible.

[HPT]

I removed the screw at the end of the tube and the cap & spring. I would like to try to remove the tube completely does anyone know how to do this? I see that the loop that is dovetailed to the barrel a few inches from the muzzle has a pin thru it - is it necessary to remove this pin to get the tube off? Is the tube threaded to the action? The tube is keeping me from removing the forestock so I can't really even see how the tube attaches to the action. Please advise how to remove tube.

[northmn]

My 357 Rossi did that and I had to take off the forearm and do a bit of relief sanding to make it behave. You have to unscrew the band screw in front of the forestock as well as the one in the end. I would try to be a little more helpful but my memory is not as good as it should be. But the forearm was very tight on the barrel.

DP

[HPT]

My gun is the 24" barrel version and does not have barrel bands, so I am not sure how the tube is held in place

[HPT]

Thanks to all who offered advise. I pressed out the pin from the loop and was able to remove the magazine tube and forestock. I quickly drove to my friends and shot 2 groups at 100 yds just before dark that had no vertical stringing as seen before. :-D

I think I will try some more groups to make sure its gone, then I'll slowly add the forestock etc. to make sure there is no relapse.

The point of impact dropped 10" with the magazine tube & forestock removed. Now I will have to figure out attach these parts without going backwards. My Winchester has the wood & tube fairly loose. Not sure about how to proceed with this gun - I was thinking letting the forestock fit the barrel tightly but preventing contact with the receiver? My Sharps is like that & it shoots well, Or is there a better idea?

Since all my load developement will need to start over, what would the recommended accuracy range of velocity for a plain base 265 cast bullet be and what powder would be recommended? I was thinking somewhere around 1350 fps or is that too fast with plain base 20:1?

[HDS]

I get 1800FPS out of my 20" Rossi lever with 20.5 grains of VV N110 over a 250gr bullet, no leading issues, plain base. I use wheel weight alloy, am going to experiment and see if I can increase the lead ratio.

[Larry Gibson]

The point of impact dropped 10" with the magazine tube & forestock removed.

I could cause almost 6" vertical stringing on my Rossi by tightening or loosening "the screw you mean is the one that goes thru the tube". Between shortening that so it put no upward tension on the barrel and shortening the mag spring I eleiminated all the vertical stringing. Mine also has a band up front and opposing screws that hold the mag tube in at the front of the handguard.

Larry Gibson

[HPT]

Hi Larry,

I was thinking about doing the following to make sure the tube "free floating" :

- shortening the screw that goes thru the mag tube so it doesn't go into the barrel
- opening the loop that the tube fits thru
- making the notch in the tube wider (so the pin doesn't touch it)
- red loctite to secure tube in receiver
- hog out forend so it can be removed without removing tube

What do you think?

[HDS]

This might be of interest:
http://www.leverguns.com/articles/paco/chapter23.htm

[Larry Gibson]

HPT

Depends on how much recoil your loads will generate. Also the more rounds in the mag the stronger the push on the mag plug to push it forward. Rossi had to reinforce the mag tube conection to the reciever with the 454 Casull M92s. Also I would shorten the screw so it goes into the hole on the barrel but doesn't put upward pressure on the barrel. My tube was/is a pretty easy slip fit in the forend so I had to do nothing there. The openings in the bands also alow a slip fit with no binding.

I suggest you try one thing at a time in this order testing after each modification to see if any additional is needed;

Shorten mag tube plug screw as mentioned.

Shorten the mag spring so it when inserted in the mag tube (in the empty rifle) it only sticks out about 4".

Open the openingings in the barrel band so there is not tension on the tube or the barrel.

Free float the barrel from the forend.

You are on the right track just a matter of finding and eliminating the problem with going the proverbial "bridge too far".

Larry Gibson

[HPT]

Thanks Larry,

I Just got back from shooting & seems to be still shooting good with the forearm & tube removed. Now I am out of powder - so need to buy more.

Up to now I've been shooting 19 gr of IMR 4227 & 265 gr pb bullet at about 1370 fps.

I switched L'il gun today cause I ran out of IMR 4227 and got about the same velocity with 16.5 grains. Having some 215 gr pb bullets I tried 14.5 grains to try to get the same velocity. Wow did the velocity jump around 200 fps between the lowest & highest!

Know I know that L'il gun shouldn't be loaded down that far- what would be a good powder to try to get around 1350 -1400 out of both 215 & 265 grain bullets?

[runfiverun]

2400.