9.3 X 57 Cutting down barrel from 24 to 20 inches. Velocity and performance loss?

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pacobillie

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I recently purchased an old Husqvarna Model 46 chambered in 9.3X57. It is a good shooter. It currently shoots about 1.2 MOA with minimal load development. My only qualm is the barrel length. I plan on using it as a brush/bush gun, and the current 24 in. barrel is a bit on the long side for that kind of use.

I shoot 285 grains PRVI soft point bullets powered by 44.6 grains of IMR 4895. I understand the PRVI is about as soft a bullet as you can get in that caliber. I estimate velocity to be about 2100 fps. I have not put that load through the chronograph yet, as my outdoor range is currently closed and I cannot use the chronograph indoors.

Would I lose much in terms of velocity and performance by cutting the barrel down to 20 inches? My concern is that I might go below the velocity where I get reliable expansion from that bullet.
 
If it is a brush gun, I would not worry about the velocity loss. With a 9.3 you are likely to lose less than 100 fps, probably in the neighborhood of 70 fps... that won't make any appreciable difference on shots under 200 yards. The shorter barrel should be more comfortable to carry over your shoulder when busting brush.
 
I don't think there is a hard and fixed "law" about velocity and barrel length, but many seem to use 25 to 30 fps loss or gain per inch of barrel. Shorten by 4 inches - guesstimate that muzzle velocity will be reduced by 100 to 120 fps. I can't find B.C. number for the PRVI 285. Assuming it is between the 286 Partition and the 286 Solid from Nosler, let's guesstimate at .400. From the Nosler tables, a B.C. 400 bullet with muzzle velocity of 2,100 fps will be at 1,912 fps at 100 yards. So, again a third "guesstimate", whatever you accomplish now with your current load and 24" barrel, you will get similar performance at 50 yards less distance. Again, I do not know PRVI design numbers, but many commercial bullets call for 1,800 fps as minimum impact velocity for reliable expansion. So, your existing set-up is about 175 yard; lose 4" barrel and it is now a 125 yard affair. Many experiments by many reloaders have shown that whatever powder gets best velocity with longer barrel, probably also gets best velocity with shorter barrel.

You are currently guessing at your velocity - might want to make an effort to get a real world value instead of an estimate. A "brush/bush" gun delivering 285 grain bullet at 125 yards at 1,800 fps should be good for a lot of game!
 
That caliber should really have a shorter barrel, but if your wanting a specific velocity than maybe you should consider rechambering to 9.3-62 as well, or shoot 250 grain projectiles.

I think that caliber would be a great little bush gun, very similar to the 358 Winchester, my preference would be 16-18"
 
shorter barrel is better for a bush gun for quicker shots, tracking and movement etc..... dont hesitate 20 inches is perfect! 18.5 is fine, you are shooting within 100 yds then really, velocity loss means nothing....

If your cutting a barrel, you have to stay within the law: barrel and overall length. If you are rebarreling, the barrel must be a factory length and within the law......
 
The original 9.3x62 loading before the second world war was over was a 286@ 2150 fps.

I've killed a number of critters with the x57 & x62 with the privi 286 bullet and in my humble opinion I think it would work fine for your application and at those velocities. So would the speer 270 grain bullet which is soft as well (softer than the privi in my experience)

I now run my 9.3 x62 @ 2500 fps with 286 partitions over reloader 17 which in my opinion is too much in the way of velocity for the PPU bullet.

Lop it off, re crown it and go hunting.
 
The only cartridge with a similar bore size I have had shortened was a 358 Norma. I had it chopped from 24” to 22 1/2”, and lost about 30 FPS.

The 9.3X57 being a smaller-cased, lower pressure cartridge should lose less. I would expect you to lose 50 FPS, MAX.
 
RickF said:
The only cartridge with a similar bore size I have had shortened was a 358 Norma. I had it chopped from 24” to 22 1/2”, and lost about 30 FPS.

The 9.3X57 being a smaller-cased, lower pressure cartridge should lose less. I would expect you to lose 50 FPS, MAX.
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If you are correct, it would be a very reasonable trade-off!
 
I cut down my husky 640 9.3×62 from 24 to 18.5 a while back. Havent chrony'd it at its reduced length but I could maybe try that out next week if I remember. Its shot a grizzly and a mountain goat in its reduced form, both with the 250 accubond. They both died quick. I think you're overthinking it, it's not gonna bounce off anything going 80 fps less. It's way handier shorter, though also much louder. It only gets shot in emergencies though so a little louder is ok.
 
45C said:
.308, I was just throwing it out there as everyone keeps saying 30 FPS loss per inch is common.
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I have tested velocities on incremental barrel chops on various cartridges... and your assumption is wrong... the results with a .308 are not the same for a 9.3 or a .22-250.
 
hoytcanon said:
I have tested velocities on incremental barrel chops on various cartridges... and your assumption is wrong... the results with a .308 are not the same for a 9.3 or a .22-250.
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No , that’s not what I assume.
I agree that different cals will have different results.

All I’m saying is, whenever this topic comes up, most people ( not me) keep throwing the 25/30 FPS out there. When that’s clearly not the case.
 
BBB said:
I cut down my husky 640 9.3×62 from 24 to 18.5 a while back. Havent chrony'd it at its reduced length but I could maybe try that out next week if I remember. Its shot a grizzly and a mountain goat in its reduced form, both with the 250 accubond. They both died quick. I think you're overthinking it, it's not gonna bounce off anything going 80 fps less. It's way handier shorter, though also much louder. It only gets shot in emergencies though so a little louder is ok.
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X2. I shortened my BRNO 602 from 25" to 20" and lost around 80 fps with 300 gr factory ammo.

It is way easier to handle with the short tube but the muzzle flash can be seen even in daylight.........

And it intimidates the he11 out of other geologists who have shot it. :)

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At one point I owned 2 rifles chambered in .358 Winchester
A BLR with a 20" barrel and a Ruger M77 with a 22" barrel.
With the same 250gr load the 22" barrel averaged 35 fps greater then the 20" barrel.

As the case capacity and bore diameter do not greatly differ, I would cut to 20" and hunt the H out of it.

357
 
few decades ago a french magazine did a test with 3 calibers 7x64, 300 win mag and the 9.3x62 and checking speed after barrel cut and factory ammo. the 9.3x62 was the only one in that test that gain after a reduction of 5 and 10cms.

so you may be surprise of the outcome with the potato thrower (nickname in Scandinavia of the 9.3x57 ..)
 
300wsm 22 down to 19" 180gr lonly lost 40fps, so 13.333fps per inch. 150 lost 55fps, 18.333 per inch.
8x57 cut 24 down to 19" 150gr lost 71fps, 14.5 per inch.
Still on the fence about cutting my .444 from 24 to 18.5
 
45C said:
No , that’s not what I assume.
I agree that different cals will have different results.

All I’m saying is, whenever this topic comes up, most people ( not me) keep throwing the 25/30 FPS out there. When that’s clearly not the case.
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You stated it again... saying that 25/30 fps loss per inch is incorrect.

I fact, the loss per inch can be considerably less and also considerably more... in small bore hyper-velocity cartridges there will be a far greater loss of velocity per inch of barrel reduction, as much as 50-70 fps per inch. For larger bore, slower cartridges there will be less loss per inch of barrel reduction, as little as 10-15 fps per inch. Your example of a single test on a single cartridge (.308) does not apply across the board.

In general the smaller the bore the greater the velocity the more velocity that will be lost per inch of barrel length reduction, and conversely the larger the bore and the slower the velocity the less velocity loss that will occur per inch of barrel length reduction.

Comparing two different barrels on two different platforms, even in the same cartridges is an entirely pointless "apples to watermelon" comparison.
 
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