338 Win Mag - How short of a barrel? Suppressed or unsuppressed?

[AkMtnRunner]

Right, compared to the 338 magnums that most 338 suppressors are designed for, such as the Lapua, the win mag is quite modest. It has the same powder volume to bore volume per barrel inch as a 30-06.

I would guess the pertinent analysis places a lot of emphasis on the pressure at the muzzle. I'm using RL17 which would have a somewhat lower pressure at the muzzle than traditional 338 powders.

 

[z987k]

I interpreted the

7.62 | 16" / 22" for Magnum Catridges​

as

7.62 | 16" (for 308, 30-'06, and sub-calibers) / 22" for (7mm Rem Mag, 300wm, etc.) Magnum Catridges​

When I talked to them about running the raptor 6 on a 18in 270wsm, they had no issue.

 

[Kal-Elk]

Well, dang. I'll have to ask them and get it in writing.

 

[Mike 338]

Don't really see the sense in burning a fair amount of your cartridge powder outside of the barrel. Magnums have a lot of powder so why not burn it inside the barrel. Also, if I stuck anything on the end of the barrel of a 338 Win Mag, it'd be a brake.

 

[Packmansion]

Don't really see the sense in burning a fair amount of your cartridge powder outside of the barrel. Magnums have a lot of powder so why not burn it inside the barrel. Also, if I stuck anything on the end of the barrel of a 338 Win Mag, it'd be a brake.

I have heard that all powder is burnt in the first few inches. I'm not a chemist but it makes sense to me. The added barrel length allows for additional work on the bullet.

 

[Kal-Elk]

My understanding was the same, powder is all burnt up in the first couple inches. Everything after that is more time for the expanding gases to add speed behind the bullet.

The reason for 338wm specifically is, current ammo shortages aside, it's a popular and proven catridge. In most scenarios one should be able to find factory ammo at the store, and find plenty of load data available on line. I admit a non-magnum catridge would likely be more "efficient", but the alternatives are relatively esoteric.

 

[Mike 338]

I have heard that all powder is burnt in the first few inches. I'm not a chemist but it makes sense to me. The added barrel length allows for additional work on the bullet.

Hmmmm, that being the case, I stand corrected. Still, something about a fireball coming out out the end of the barrel indicated there was still some work to be done.

 

[Andouille]

Don't really see the sense in burning a fair amount of your cartridge powder outside of the barrel. Magnums have a lot of powder so why not burn it inside the barrel. Also, if I stuck anything on the end of the barrel of a 338 Win Mag, it'd be a brake.

Probably not a huge deal because 338 Winmag isn't a "huge" magnum and surprisingly only has a case volume of 86 gr of water versus 91 for 300 winmag. 86 gr minus bullet volume leaves room for 73ish grains of powder at max based on a quick glance at load data. It appears that 338 WM generates higher downrange energy at similar load weights as 300 WM and there are quite a few folks running 20" barrels for WM still getting respectable speeds.

Combine the moderate powder load with the high efficiency of the 338 WM and it seems like a reasonable candidate for a short barrel magnum that doesn't give up too much speed. Max speed would probably be with an impractical >28" barrel length, so at some point it comes down to personal preference and planned use scenarios.

 

[Mike 338]

Probably not a huge deal because 338 Winmag isn't a "huge" magnum and surprisingly only has a case volume of 86 gr of water versus 91 for 300 winmag. 86 gr minus bullet volume leaves room for 73ish grains of powder at max based on a quick glance at load data. It appears that 338 WM generates higher downrange energy at similar load weights as 300 WM and there are quite a few folks running 20" barrels for WM still getting respectable speeds.

Combine the moderate powder load with the high efficiency of the 338 WM and it seems like a reasonable candidate for a short barrel magnum that doesn't give up too much speed. Max speed would probably be with an impractical >28" barrel length, so at some point it comes down to personal preference and planned use scenarios.

Well, when you put it that way, yes it would be an acceptable candidate for a short barrel magnum if you were to compare it with all the other magnums. But... you don't choose a 338 WM for it's downrange superiority. You use one to spin an elk or bear around with a heavy bullet in near darkness, usually shooting offhand. Follow up shots are not so uncommon. You definitely don't use it as a range toy. My 26"ers will still throw a fair fireball out the end but you don't get night blind from them. That said though, a guy could chop one down and fill several truckloads with game so the only way you'll know you'll like it is to do it.

 

[z987k]

Hmmmm, that being the case, I stand corrected. Still, something about a fireball coming out out the end of the barrel indicated there was still some work to be done.

There's still work to be done if you made the barrel 6 feet long.
There's no fireball with a suppressor.

 

[z987k]

I have heard that all powder is burnt in the first few inches. I'm not a chemist but it makes sense to me. The added barrel length allows for additional work on the bullet.

It depends on the powder and the pressure you're achieving.

 

[Bluefish]

I have heard that all powder is burnt in the first few inches. I'm not a chemist but it makes sense to me. The added barrel length allows for additional work on the bullet.

Not necessarily. Really depends on the cartridge and powder. I was recently looking at a 25-06 and it has a slow burn with a lot of residual pressure. Every extra inch was between 75-100 fps. Yet looking at a 35 whelen the residual pressure is a few 1000 psi lower.
in regards to a Raptor, call them and ask. i have called and asked about going below the published minimum length and it’s a function of how much powder and residual pressure. They are conservative in the published numbers to keep people from doing dumb stuff.

 

[Packmansion]

Not necessarily. Really depends on the cartridge and powder. I was recently looking at a 25-06 and it has a slow burn with a lot of residual pressure. Every extra inch was between 75-100 fps. Yet looking at a 35 whelen the residual pressure is a few 1000 psi lower.
in regards to a Raptor, call them and ask. i have called and asked about going below the published minimum length and it’s a function of how much powder and residual pressure. They are conservative in the published numbers to keep people from doing dumb stuff.

That's interesting. This is what I have used to estimate loss. I know every gun is a little different.
https://rifleshooter.com/category/barrel-length/

 

[Bluefish]

That's interesting. This is what I have used to estimate loss. I know every gun is a little different.
https://rifleshooter.com/category/barrel-length/

I was using quickload and grt. You can see how much different the pressure curve is depending on the cartridge. Just changing the bore from .257 to .358 changes the powder required and where in the barrel the pressure peak happens. Didn’t spend a lot of time on the difference, but noticed it was enough I could see it in the graphs.
on my 45-70 sub loads, maybe a 10 fps difference between 14” and 20” barrels. On that particular load, all the powder burns in the first few inches. The 25-06 is not that way. slower Powders are needed. Even slower than the 35 whelen. probably needs some more research. I am sure this effects how well a can works and the pressures it encounters.

 

[Packmansion]

It depends on the powder and the pressure you're achieving.

Do you have examples or data or takeaways from expirience? Also at what length is say 99% of powder burned? My other thought is does some powder just never get burnt?

 

[Bluefish]

Do you have examples or data or takeaways from expirience? Also at what length is say 99% of powder burned? My other thought is does some powder just never get burnt?

I don’t think there are any hard rules of how many inches of barrel to burn powder. Depends on too many other things. powder burn speed depends on pressure. Burns faster at higher pressure.
blue dot is one powder where lack of pressure really slows down burn speed. Have had squibs due to low pressure, yet the same load works in tighter chambers With higher pressure.
yes, some powder may not burn or burn after leaving the barrel. I have had this happen with shotguns. Impressive to see at dusk when burning flakes come out your barrel porting. Long barrels, but low pressure Relative to rifles.

 

[z987k]

Do you have examples or data or takeaways from expirience? Also at what length is say 99% of powder burned? My other thought is does some powder just never get burnt?

Go play with GRT or QL. Spend a few hours making up loads and it'll do more for your understanding than I can possibly type here.

 

[Packmansion]

Go play with GRT or QL. Spend a few hours making up loads and it'll do more for your understanding than I can possibly type here.

Ive found GRT to be way off compared to my actual loads.

 

[z987k]

Ive found GRT to be way off compared to my actual loads.

Then you're not using it properly. You have to tune it. Garbage in, garbage out. If you're using a stock supplied powder model for anything but not exploding, you've not read the directions. To say nothing of actual case size, seating depth, bullet resistance etc.

Regardless, the pressure curve and powder burnout give you a really good idea of what is going on. Like you should be able to see that a powder's burn rate is entirely dependent on the pressure. Running N560 at 30kpsi, there's no barrel length that would ever give you a complete powder burn. At 50kpsi, it's entirely different.

 

[Packmansion]

Then you're not using it properly. You have to tune it. Garbage in, garbage out. If you're using a stock supplied powder model for anything but not exploding, you've not read the directions. To say nothing of actual case size, seating depth, bullet resistance etc.

Regardless, the pressure curve and powder burnout give you a really good idea of what is going on. Like you should be able to see that a powder's burn rate is entirely dependent on the pressure. Running N560 at 30kpsi, there's no barrel length that would ever give you a complete powder burn. At 50kpsi, it's entirely different.

I am still learning just started tinkering with it. How close to real world velocity are you getting?