M92 357 16" versus 20" barrel

[Maj Dad]

I searched here with no luck, so let me ask: what are some of the pluses & minuses for the 16" vs the 20" (or even the 24")? I just got a 20" M92 44 last Nov or Dec, love it and the 20" bbl & I have decided to go ahead & get a 357. The gun shop at the Shaw AFB BX has a 16" in stock & I almost bought it yesterday afternoon, but thought I'd float this out first. My personal thought is that the 20" will be a tad less noisy, but since I wear ear muffs &/or plugs, that's not a show stopper. What's the velocity loss for 4"? Just looking for input & your comments.
Thanks,
George J.

[AhnkoChee]

From the research I have seen all the powder in the 357 magnum cartridge is burned up in 16 inches of barrel so you do not gain any velocity with the extra 4 inches and in fact loose some velocity from friction the last 4 inches though miniscule. The main advantage would be the longer sight radius which with open sights adds to accuracy. On both my 16" barreled 357 mag rifles I added receiver peeps which increased the sight radius thus making up for loss from a shorter barrel. If I can find the information on velocity loss in in 357 mag barrels I'll post it.
In my opinion the 16" is the most efficient length for the 357 magnum.

[Lostcoast]

From everything I have read the velocity loss is not sufficient to make a meaningful difference in the terminal performance of .357 within its useable range. So really it comes down to a matter of preference in terms of handling characteristics. I know many folks, including myself, have purchased the 16" model 92 for maximum portability. It really does carry a little differently than the 20" barrel version, and seems a little "handier" for moving through the brush or carrying in a backpack..

[Deleted User 327]

From the research I have seen all the powder in the 357 magnum cartridge is burned up in 16 inches of barrel so you do not gain any velocity with the extra 4 inches and in fact loose some velocity from friction the last 4 inches though miniscule. The main advantage would be the longer sight radius which with open sights adds to accuracy. On both my 16" barreled 357 mag rifles I added receiver peeps which increased the sight radius thus making up for loss from a shorter barrel. If I can find the information on velocity loss in in 357 mag barrels I'll post it.
In my opinion the 16" is the most efficient length for the 357 magnum.

While I've seen that position written up a lot, true testing such as Ballistics By The Inch's data doesn't support that 'wives tale' as their data clearly shows velocity gains up through 18" barrels. Further, the ammo they selected and compared were specifically designed for pistol length barrels rather than rifle length. My own chrono testing using my 20" carbine and 24" rifle length 357mag Rossis clearly shows that when using full charge weights of slow burning magnum pistol powders (specifically H110), magnum primers, and 158grn bullets I consistently get higher velocities in my 24" rifle than my 20" carbine which also runs against the above stated research. The specific velocities and conditions are as follows:

Range Conditions:
Range at 6,100ft asl, 84° sunny day, little if any wind

Ammo Tested:
357mag handloads consisting of New Starline Brass, Zero 158grn JSP Bullets, CCI Small Pistol Magnum Primers (CCI 550), 16.7grns H110 Powder, with an OAL of 1.570".

Firearms:
2009 Rossi M92 20" Round Barreled Carbine and 2009 Rossi M92 24" Octagon Barreled Rifle

Chrono Testing:
Each firearm was fired 5 rounds in 30 seconds to warm up the barrels then a 10rd string fired in under 2 minutes, a pause of a few minutes to reload and then a second 10rd string fired in under 2 minutes. Both 10rd strings were combined and the average velocity calculated.

Chrono Results:
20" Carbine - Average Velocity = 1,789fps, SD - 17fps, ES - 23fps
24" Rifle - Average Velocity = 1,822fps, SD - 14fps, ES - 19fps

It's true that less than full charge weight loads and loads using fast burning pistol powders show velocity decreases in my 24" rifle vs my 20" carbine. This is to be expected because the lower charges produce less total gas volumes which causes the charge to fail to accelerate the bullet down the full length of the longer barrel.

It's also true that even higher charge weights of magnum pistol powders such as were used when the 357mag was being developed back in the 30s, produce even larger velocity differences between 20" and 24" barrels as my further testing proved. When I tested hot 357mag loads using the above components but with 17.7grns of H110 (a charge weight commonly used at that time) at the same range and temperature, I got the following results:

Chrono Results:
20" Carbine - Average Velocity = 1,941fps, SD - 13fps, ES - 17fps
24" Rifle - Average Velocity = 1,977fps, SD - 9fps, ES - 13fps

Both my initial and hot load data show velocities higher than those reported in Ballistics By The Inch's data for 18" barrels demonstrating that this slow burning magnum powder does benefit from the longer barrel length. So, this data shows that AhnkoChee's statements above, while commonly believed, are simply not the case in all instances.

[44-40 Willy]

Thanks Steve. I've made the same claim but couldn't find the old notebook that had the data in it so I wasn't too prepared to argue the point with some here. I used my 24" Navy Arms 1892 and Marlin 1894 Carbine both in 357.

I do have the end results with the Navy Arms though in my load sheets. Using a 158gr XTP, I was getting 1980fps with a middling dose of H110 and the same powder charge and a 145gr Silvertip JHP got me 2050fps.

[ironhead7544]

I have had both and prefer the 16 inch for the 357 Magnum. I could tell no difference in accuracy with the stock sights. The 16 incher is very handy and a little lighter.

[pricedo]

I searched here with no luck, so let me ask: what are some of the pluses & minuses for the 16" vs the 20" (or even the 24")? I just got a 20" M92 44 last Nov or Dec, love it and the 20" bbl & I have decided to go ahead & get a 357. The gun shop at the Shaw AFB BX has a 16" in stock & I almost bought it yesterday afternoon, but thought I'd float this out first. My personal thought is that the 20" will be a tad less noisy, but since I wear ear muffs &/or plugs, that's not a show stopper. What's the velocity loss for 4"? Just looking for input & your comments.
Thanks,
George J.

I love my 2 x 16" Amadeo Rossi 92s in 357 Mag & 44 Mag.
I find the ear muffs/plugs really cut down on noise when going through foliage when hunting.
Still can't seem to sneak up close on those big, wise old bucks though.

My Amadeo Rossi 92/454 has a 20" barrel. The 454 would probably benefit more in terms of velocity from the extra 4" of barrel but only a chronograph could tell for certain if there is any real advantage.

[Barry in IN]

Looking at the Ballistics By The Inch data, it looks like it depends on the ammo used. If I'm looking at it right, it looks like some loads gain a little after 16" and some lose a little.

How many fewer cartridges does the 16" hold? Two?

[pricedo]

Looking at the Ballistics By The Inch data, it looks like it depends on the ammo used. If I'm looking at it right, it looks like some loads gain a little after 16" and some lose a little.

How many fewer cartridges does the 16" hold? Two?

The slower burning powders generally benefit more from longer barrels.

[RAINS42]

If you load your own rounds then you can take advantage of the 20' barrel better. Most 357/38 factory ammo is geared towards pistols and you'll see little to no diff in 16' vs. 20' barrels. I love the weight, balance and feel of my 16'. Would not buy a 20' model but maybe an 18' if Rossi made one. If it's a range toy then nab the 20'. If it's a truck/packing rifle then I suggest the 16' barrel. 357 is loud out of it but .38+P gold dot factory ammo still hits hard and is not very loud at all. Good luck and have fun!