Twist rate and bullet stabilization

The Rossi Model R92, a lightweight carbine for Cowboy Action, hunting, or plinking! Includes Rossi manufactured Interarms, Navy Arms, and Puma trade names.
massmanute
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Twist rate and bullet stabilization

Post by massmanute »

Hi. New person here.

I recently bought a .357 magnum Rossi M92. (Stainless model, 16" barrel.) The twist rate is one turn in 30". What bullets and loads will/will not stabilize in this rifle? I did contact Buffalo Bore and they said that their 180 grain load will stabilize.

Do any of you have additional information?

Thanks.
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Re: Twist rate and bullet stabilization

Post by pricedo »

massmanute wrote:Hi. New person here.

I recently bought a .357 magnum Rossi M92. (Stainless model, 16" barrel.) The twist rate is one turn in 30". What bullets and loads will/will not stabilize in this rifle? I did contact Buffalo Bore and they said that their 180 grain load will stabilize.

Do any of you have additional information?

Thanks.
My rifle is a "blue" version of yours and has been quite accurate with anything I've put in it......125s.........158s......wadcutters......semi-wadcutters ......jacketed.........lead......you name it.
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Re: Twist rate and bullet stabilization

Post by runfiverun »

i have only used 125's and 158's in my 357 so far i do have a 180 mold but haven't felt the need to go past the 158 rnfp mold and the 357 case.
i have tried some 158 swc's in the 38 case but it don't like to feed them from the tube [shoots them good enough for levergun silhouette though]
once i used the rnfp mold and they slid through the action so slick, i just worked up a load with some herco i had on hand, and loaded up over 2500 rounds for my everyday load.
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Re: Twist rate and bullet stabilization

Post by massmanute »

Thanks for responses so far. Has anyone tried some of the heavier bullets, such as 180 grain, or even 200 grain?
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Re: Twist rate and bullet stabilization

Post by pricedo »

massmanute wrote:Thanks for responses so far. Has anyone tried some of the heavier bullets, such as 180 grain, or even 200 grain?
Nope, sorry, couldn't see the point as the 158s were knocking over the steel silhouettes at my range very nicely.
I noticed that the big Lyman paperback reloading manual #46 has a fair number of cast lead loads.
Good reference if you're looking for a starting point with various cast bullet weights and powders.
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Re: Twist rate and bullet stabilization

Post by Ranch Dog »

I have some load data on my site as well with my 175-grain bullet, the TLC359-175-RF.

TMT, one of Rossi Friendly Vendors, has a Bullet Stabilization calculator on his web site.
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Re: Twist rate and bullet stabilization

Post by WyrTwister »

runfiverun wrote:i have only used 125's and 158's in my 357 so far i do have a 180 mold but haven't felt the need to go past the 158 rnfp mold and the 357 case.
i have tried some 158 swc's in the 38 case but it don't like to feed them from the tube [shoots them good enough for levergun silhouette though]
once i used the rnfp mold and they slid through the action so slick, i just worked up a load with some herco i had on hand, and loaded up over 2500 rounds for my everyday load.

I have mostly .38 Special brass to load for my Rossi M92 & Winchester M1892 ( converted at some point in time to .357 Mag ) . I load the RN or SWC home cast bullets one groove further out , giving me ~ the OAL of factory .357 Mag ammo .

The Rossie will feed .38 Special length , although not as well as .357 Mag OAL .

The Winny just barely will feed .38 Specials .

By seating the bullet long , I can use the .38 Special brass & they feed OK in both .

Seating them long also gives ~ the same internal volume and pressure as .357 Mag brass would , with ~ .357 Mag powder charges .

I bought the RN mold because the Winny is less tolerant of SWC's , than the Rossi .

If a lever gun will not feed a RB bullet , it probably will not feed anything .

Pretty much the same with a semi-auto hand gun .

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Re: Twist rate and bullet stabilization

Post by Barry in IN »

I have a rebored Win 92 .357, and I think it has a 1-20 twist. The heaviest I have shot through it has been a cast 180 WFN (WFN) that actually weighs around 185 when cast from my alloy. It shoots really well. in fact it may be that rifle's preferred bullet.

However, with barrel twist rates, the bullet shape has to be taken into account because its the bullet's length that can give you trouble. A stubby 180 usually requires less twist than a longer pointier bullet of the same weight. It should even do better than a longer bullet that weighs less, say 160. The WFN bullet my rifle likes is hardly any longer than it needs to be. The only .358 mould I own that is heavier is a Lyman 358430, which is a 195-200 grain RN. Being a RN, I doubt I'd use it in that rifle but I bet it would shoot because it is about as short as possible for it's weight and hardly longer than some 158s I have. The long bearing surface can't hurt either. On the other hand, there are some .358 moulds out there intended for the .35 Rem that weigh around 200 grains but have a long gradual curve to the nose that makes them pretty long. They might not do very well, even if you could get them in the rifle even single loading. I seriously doubt they would feed from the magazine.
This was a long trip to get to my point. And that is, I would think any bullet that would give a functional OAL would be handled by that twist.
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Re: Twist rate and bullet stabilization

Post by Jacko »

My 92 has a 24" barrel. I was shooting Westcast rnfp 180 gr commercial Cast proj until a few months back. Loads using 2400, ADI 2205 [ H4227 ], W296, ADI AP70N [Universal ] & Lilgun all shot well with these Proj out to 200 yards with no signs of instability. I recently bought a Ranchdog TLC 359 175 Mould, sized to .359 and Ligun get excellent accuracy and near enough the same trajectory as my ADI 2205 [ H4227 ] / Lee 158 gr GC SWC out to 50 yards. Have not had an oportunity to shoot further with these Proj at present.

regards Jacko
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Re: Twist rate and bullet stabilization

Post by Missionary »

Good morning
Trying not to be real technical... it all depends on how many RPM´s it takes to keep a bullet stabile. Too fast is OK. Too slow and it wanders. Length is important. A long length bullet takes more spin than a short length bullet of the same weight. A wadcutter is about the easiest bullet type to stabalise. Short for weight. Cast bullets also are great as they are generally short for their weight .
So bottom line... if that bullet needs 5x rpm´s to stay stable then that is where accuracy begins. Until you push it fast enough for that twist rate to impart 5x rpm´s to that bullet then it will wobble in random directions. There are all sorts of fancy formulas you can use to maybe come close to needed velocity. Far easier is just realize that a slow twist barrel needs FAST pushed bullets to shoot accurately. Add length to the bullet and you need to add more fps to that FPS to get accuracy.
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