1 in 30 twist Rossi M92 357 mag??

[A pause for the COZ]

Is this the normal twist rate for this fire arm? I had read comments about people using the Rossi in 357 mag as a hog getter.
I would not feel comfortable doing this. Since 180gr projectiles cant hit a paper plate at 50 yards.
125gr will drive tacks at 100.
Any code I am missing , what are you guys finding?

[Ranch Dog]

Since 180gr projectiles cant hit a paper plate at 50 yards.

Don't know about that, just shot a hog at 70 yards and a whitetail at 90 yards with my 175-grain RF nose bullet, both right through the heart.

[A pause for the COZ]

What powder are you using? I tried Unique, Herco and 2400. I just couldn't get the heavies to stabilize.

[massmanute]

Is this the normal twist rate for this fire arm? I had read comments about people using the Rossi in 357 mag as a hog getter.
I would not feel comfortable doing this. Since 180gr projectiles cant hit a paper plate at 50 yards.
125gr will drive tacks at 100.
Any code I am missing , what are you guys finding?

As I understand the situation, it depends a lot on the design of the bullet you are using. If the "center of pressure" and the center of gravity of the bullet are close to the same point then a slower twist can still stabilize a heavy bullet. I believe that the heavy bullet designs from ranchdog are designed this way, so even though the bullets are heavy, and the Rossi twist rate is slow, the bullets still stabilize and can be shot accurately. This is especially true if the load has some "oomph" behind it, to use the technical term.

Someone correct me if I am wrong.

Massmanute

[Ranch Dog]

As I understand the situation, it depends a lot on the design of the bullet you are using. If the "center of pressure" and the center of gravity of the bullet are close to the same point then a slower twist can still stabilize a heavy bullet. I believe that the heavy bullet designs from ranchdog are designed this way, so even though the bullets are heavy, and the Rossi twist rate is slow, the bullets still stabilize and can be shot accurately. This is especially true if the load has some "oomph" behind it, to use the technical term.

That is correct massmanute. I would also add that a bullet needs to fit the freebore, leade, step, and throat of the chamber. The Greenhill formula is a very simple set of variables for a very complex issue. It looks at Bullet length in inches and Diameter of the bore grooves in inches. In other words it is determining the stability of a cylinder, not the complex characteristics of a bullet. In a nutshell, the Greenhill formula is BS.

What powder are you using? I tried Unique, Herco and 2400. I just couldn't get the heavies to stabilize.

I use Lil' Gun in all my short action rifle cartridges; 25-20 Win, 32-20 Win, 357 Mag, 41 Mag, 44 Mag, 45 Colt, 480 Ruger, and I suspect the 454 Casull. My only second choice would be H110/W296. The difference in the two is that a max load of Lil' Gun is going to be at what I consider the limit of compression, 105% of the case capacity and deliver the greatest velocity. H110 is slightly looser, 102% across the range of cartridges, and slightly slower (about 98% of the velocity produced by Lil' Gun). Accuracy is good with H110/W296 but my experience with all the cartridges above in both the Marlin and Rossi rifles, the accuracy will be tighter with Lil' Gun. H110/W296 I see 100 yard 5-shot groups at 1.75" to 2.00" and Lil' Gun will tighten them down to 1.25" to 1.50". Important when you are not shooting off the bench or further downrange. I think the slightly tighter compressed charge provides for a more uniform powder burn at combustion.

You did not mention a specific bullet so working with my TLC359-175-RF I would consider 13.1-grains of 2400 as a max load and that load not being tight enough at only 93% of the case capacity. The velocity is also 100 FPS off of what my Lil' Gun load is producing. I would not consider Herco (8.3-grain, 89%, at 1500 FPS) or Unique which would not meet my desire of a minimum fill capacity as it is less than 86%. Sure these powder will get the bullet out the barrel but you cannot expect the performance to be optimum.

I would also take a close look at how the bullet's nose profile fits the chamber cut. It needs to fit the features (freebore, leade, step, and throat) like a glove so that it is supported at combustion. This is a image produced of the Marlin 1894C's chamber dimension for the measurement taken of a chamber cast. I going to use the Marlin's chamber cut to point out the features mentioned because the cut Marlin made has them all.

chamber_closeup.jpg

When I was in business a common email question I would receive would be "why does my 1894C need a .359" bullet in that the groove diameter is only .355" as determined by slugging the barrel?" The answer is that a slug only can measure groove (and bore) diameter not freebore, leade, step, and throat. In the case of the Marlin bullet diameter is used to "get out ahead" of the step and fill freebore and leade, and then bullet ogive design is used to fill the remainder of the throat. The Rossi actually has a tighter cut on the freebore and leade (the bore/groove diameter cut is very close to the Marlin) so it needs a smaller diameter front band (357") but a specific length is still needed to fill it.

Most bullets are designed by the demands of the human, not the rifle. "I want a XXX-grain bullet with a nose like this." The way it should really work is "the rifle needs this". There is only one way to do that and this is why Greenhill's formula is just too simple.

With the bullets you have in hand, what I would do is take some cartridge length measurements. With nothing in the rifle and the bolt closed run a cleaning rod down the barrel. With a fine Sharpe pen carefully mark the rod at the muzzle. I lay the pen on the radius of the muzzle and rotate the rod. Now open the action and drop a bullet in the chamber. Use something like a flexible cleaning rod to move it tight into the chamber. Take the same measurement on the cleaning rod and then carefully, with a caliper, measure the difference between the two marks. If the measurement is greater than 1.590", the bullet isn't going to work. If it is at 1.590" or less it has a chance and the measurement you determined should be used as the overall length of the cartridge. Choose a powder that does a better job of filling the case and that produces more velocity (Lil'Gun, W296, or H110).

[massmanute]

Michael,

Any info on how well your 175 grain design fits the recent Rossi M92 chambers?

massmanute

[dpe.ahoy]

LilGun has become my go to powder for the 357mag, seems like a perfect match for the case capacity of this cartridge. It has replaced H110/W296 as "the" powder for all my firearms chambered in 357 mag. DP

[Ranch Dog]

Any info on how well your 175 grain design fits the recent Rossi M92 chambers?massmanute

I have two 2012 357 Mags, both shoot and cycle very well. Just took this boar a few minutes ago!

hog_130115.jpg

[massmanute]

Nice pig Michael.

[A pause for the COZ]

I will try to digest this info and will for sure give it another try. if I can get some heavies to shoot accurately.
I would be soooooooo Happy.
Thats why I got this gun.