My last accuracy improvement fix... radical!

[Xshot]

I like my 20" SS M92 in .357 mag. What I didn't like is the constantly changing vertical POI from POA. Some days it would be right on the money and other days it would string vertically up to 5 inches. After much testing I found the screw for magazine tube plug to be the sole contributor to the inconsistency. Basically, the tip of the screw will shift within the recess cut in the bottom of the barrel.

First I used Devcon (liquid version) to epoxy the barrel band to the the magazine tube. I did this to precisely locate the barrel band where I wanted it on the mag tube and to minimize movement of the mag tube once the rifle is fully assembled. Next I drilled through the barrel band and mag tube and tapped the hole for a 6-32 SS set screw. Lastly, I shortened the mag plug screw so that it will never again touch the barrel. The cross screw for the barrel band is now the stop instead of the mag plug screw. Moreover, the cross screw needs only to be snug and not tight on the barrel.

Since I've done this mod, I haven't had any vertical strings.

FWIW - I'm anal about accuracy and consistency. This mod may not be necessary for a lot of people.

[akuser47]

Nice work thanks for sharing I am sure this will help add to our collective information here. Do you have any before and after examples of targets by chance? Either way good results speak for itself.

[Xshot]

I didn't keep any of the targets. However, during my problem determination testing I could induce a vertical string of 5 shots. These shots were perfectly aligned over a 6 inch spread. As the mag tube moved forward the mag plug screw also moved forward from its neutral position. This caused it to climb the side wall of the recess cut into the bottom of the barrel. No doubt it was changing barrel harmonics and even pushing/wedging the muzzle upwards. Through my experiments I found that it didn't take much movement, just a few 1000's to make the POI move upwards. I had previously filed down the screw to relieve contact with the barrel, but I could see that it wasn't going to resolve the problem as long a the mag tube moved.

[Ranch Dog]

First I used Devcon (liquid version) to epoxy the barrel band to the the magazine tube. I did this to precisely locate the barrel band where I wanted it on the mag tube and to minimize movement of the mag tube once the rifle is fully assembled.

I really like this part of the fix. I've actually been considering this fix for a year now on all of my R92s and RGs. More from from the point of recoil fatigue.

[Tuco Ramirez]

This is very interesting.... will be keeping track of this thread.

[45LC92]

Just curious, why the Devcon and the set screw. Wouldn't the set screw have sufficed? Sorry if it's a dumb question.

[Xshot]

Well... to be honest I wasn't sure how this fix/mod would be received. I was suspicious of the mag plug screw from the beginning. I suppose my earlier and constant fiddling, or just cleaning, of my 92 masked the problem. Because each time I reassembled the rifle I would return the mag plug screw to its neutral (i.e. relieved) position.

Previously, I had slicked up the action and smoothed the trigger. In addition, I relieved wood from the forearm to free-float both the barrel and the mag tube. Lastly, I opened up the forearm barrel band so I didn't contact the barrel. All of these adjustments steadily improved the accuracy and consistency of the rifle. A side benefit is the rifle is now easily disassemble and reassembled with all these stress point relieved.

Over time I found the POI would vertically diverge from POA. I could take my 92 out of the safe and bang off a few shots and hit my mark as expected. But later in the day it would shoot high. This was after making the rounds on my Polaris ATV with the 92 in its scabbard - muzzle down. In the past, I had attributed the shooting high to me or the barrel getting hot, but now I new something was moving and causing the problem. I took a full day and confirmed that recoil, from 7 - 10 shots, would also slightly move the mag tube and cause the mag plug screw to bind against the barrel. If I reset the mag plug screw to its neutral position or backed it out to where it was completely clear of the barrel the vertical stringing was eliminated.

The Devcon by itself will not lock the mag tube to the muzzle barrel band. The set screw is required for a permanent solution. The 92 is easily disassembled and reassemble with this fix/mod. The muzzle barrel band just slips of the barrel and remains attached to the mag tube. The mag spring can be removed and installed by threading it past the set screw. The set screw doesn't interfere with with the compression/decompression of the spring, because it's so far forward in the mag tube. It just take a little more time and finesse to reassemble.

As much as I like my Rossi 92, I like it much more now that it is less finicky and repeatably consistent in its performance.

[Xshot]

Just curious, why the Devcon and the set screw. Wouldn't the set screw have sufficed? Sorry if it's a dumb question.

No such thing as a dumb question.

I used the Devcon for 2 reasons. 1.) To precisely locate and fit the muzzle barrel band onto the mag tube in its relaxed position. 2.) To minimize movement between muzzle barrel band and mag tube without have to crank down on the cross screw for the barrel band. I just wanted this screw to be snugged up and not super tight on the muzzle portion of the barrel.

[Johnz]

On my .357 blued rifle, the mag tube is slightly warped so they drilled the hole for the mag plug screw off center. That effect straightens the tube when you tighten the screw, plus it provides the correct spacing between the barrel & mag tube which they would otherwise be touching. You think there aren't accuracy killing stresses in that arrangement?

[Xshot]

On my .357 blued rifle, the mag tube is slightly warped so they drilled the hole for the mag plug screw off center. That effect straightens the tube when you tighten the screw, plus it provides the correct spacing between the barrel & mag tube which they would otherwise be touching. You think there aren't accuracy killing stresses in that arrangement?

Are you asking my opinion? How does it shoot? The muzzle barrel band (for round barreled 92's) should provide the proper spacing between mag tube and barrel. I haven't looked at octagon barrel 92's, so I can't say.