twist rate for 308 winchester
- Thread starter joey.45
- Start date
one turn in 10. that was figured out when the first 30 cal bullets were designed and most of the first weights issued to the militaries started useing them went with 220 grn projectiles.
Today, some people say one in twelve is best.
bearhunter
Today, some people say one in twelve is best.
bearhunter
you want to seriously re-think that 220 in a 308 winchester- 1 velocity concerns,( moves too slow for any decent range) 2 when seated to 308 mag length , the BULLET SITS IN THE POWDER by a good margin,- ie it's just too much weight& length for the case- the 308 should be loaded with 180's as a max, possibly 190, but that's all- seated to factory length , the 180 sits right on top of the powder in the case- the 190 has a slight compression, and whe you get to 200 in factory, you get tough extraction, blackened primers, and all sorts of stuff i can't remember from- it's just bad news period- now you WANT to go up ANOTHER 20 grains- the 220 is MEANT for the '06 - this is where that extra half inch of length, the extra powder capacity , and the faster twist all come into play
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It'd work fine in a single shot. Some guys have .308s built on a L/A so they can seat the bullets out further. Even my Sako has a longer than normal magazine, and a model 70 mag is over 3".
Velocity would still be decent, as my Lee manual lists the .308 with a 225gr bullet at over 2300fps with H4350, and they have a 250gr that shows 2100fps, all with a 24" barrel.
Your throat depth may have more effect on it than anything.
It may not be conventional, but that doesn't mean it won't fly. Maybe I'll order up some big ol' bullets and prove the naysayers wrong.
It'd work fine in a single shot. Some guys have .308s built on a L/A so they can seat the bullets out further. Even my Sako has a longer than normal magazine, and a model 70 mag is over 3".
.308s built on a long action? Why wouldn't you use a .30-06
.308s built on a long action? Why wouldn't you use a .30-06
Depending on the action, you'd be into the same thing. The extra length of the case is taking your space for seating the bullet out longer. Therefore you'd have to seat deeper into the powder.
To the nay-sayers, I say bah!!! - I shoot 220 grain Hornady RN's in one of my 308's, seated to approx 2.810 OAL, and it works just fine (and it is the 1:12 twist). Actually, in that gun, the 220 grain bullet is the single most accurate load I've ever tried.
I have done it with Reloader 15 (which was a little spooky, as I had no reloading data to go by - I had to do some guestimation and watch the chronograph closely - I stopped at 2300FPS).
I later ran across a friend of mine who had a book with load data for Win760 and the 220 grain Hornady. The load data was as follows:
Start: 42 grains - 2175FPS @ 42,000 CUP
Max: 44 grains - 2300FPS @ 47,000 CUP
As I had a line on a whole whack of very cheap 760 at the time, I switched to 760 for these loads. Accuracy isn't quite as good as with Re15, but it's still very acceptable.
I have also seen load data for 4350 and 220 grain bullets that claims about 2350 FPS, but can't recall the exact load off the top of my head.
For reference of what that bullet at that velocity can do, I know an old timer who used to shoot those 220 grain hornady RN's at 2300FPS out of a 30-06 for bear medicine when he was prospecting. He claimed that bullet would make a stem to stern penetration on a grizz.
It's not a long range load by any means, but so long as you can guesstimate your hold-over, I'd say anything inside of 300 yards was fair game.
I have done it with Reloader 15 (which was a little spooky, as I had no reloading data to go by - I had to do some guestimation and watch the chronograph closely - I stopped at 2300FPS).
I later ran across a friend of mine who had a book with load data for Win760 and the 220 grain Hornady. The load data was as follows:
Start: 42 grains - 2175FPS @ 42,000 CUP
Max: 44 grains - 2300FPS @ 47,000 CUP
As I had a line on a whole whack of very cheap 760 at the time, I switched to 760 for these loads. Accuracy isn't quite as good as with Re15, but it's still very acceptable.
I have also seen load data for 4350 and 220 grain bullets that claims about 2350 FPS, but can't recall the exact load off the top of my head.
For reference of what that bullet at that velocity can do, I know an old timer who used to shoot those 220 grain hornady RN's at 2300FPS out of a 30-06 for bear medicine when he was prospecting. He claimed that bullet would make a stem to stern penetration on a grizz.
It's not a long range load by any means, but so long as you can guesstimate your hold-over, I'd say anything inside of 300 yards was fair game.
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The thing with the 220 grain bullets, is you're using fewer grains of powder (significantly) than you would when using say, a 165 grain bullet. There's still air space in my 308 loads for the 220 grain bullets - the intrusion into powder space is a non-issue.
- Location
- Somewhere on the Hudson Bay Coast
As some may have noticed, I'm a heavy bullet fan. I tend to shoot 325 gr .44's, 380 gr .375's and 240 gr .308's.
If you are concerned about the rate of twist that means you are considering a new barrel, so I'll tell you what I did with my .308. When I had it chambered I made up a dummy round with a 200 gr MK so that the bullet was seated so only the boat-tail was below the neck. This was sent to my gun smith who cut the chamber so the lead would allow for this long OAL. This additional powder capacity allows me to come within a hair of 2700 fps with that bullet from a 1:8 28" barrel. That's a far cry from the 2400 fps maximum listed in the loading manuals. Now, you might not get that velocity from a short barrel hunting rifle, but it will behave more like a .30/06 if you want to shoot heavy bullets. Before taking that step though, you want to make sure that your magazine will accept that long a cartridge.
If 220's are as heavy as you will load, then a 1:10 is probably the correct choice, in fact a 240 gr Woodleigh will also stabilize in a 1:10 barrel. For the naysayers who claim that a fast twist destroys light bullet accuracy, I was out a few weeks ago with my .308, and was hitting clay birds at 825 yards with 168 gr Nosler J-4's, but I haven't tried any long range shooting with lighter bullets from that barrel to say that accuracy would hold up with 155's. Based on my experience with fast twist barrels I think it will, but I haven't done it.
The bottom line is, I have discovered that I am limited by too slow a twist far more often than I am too fast a twist. My wife's .30/06 Husky has a 1:12 barrel, and that barrel will not stabilize 240 gr Woodleighs, but my 1:10 .30/06 Brno does. My Lilja 1:10 .243 will not stabilize the long 107 gr MK's, but a 1:7 would. My old 1:7 .222 shot every .224 bullet I loaded for it beyond what might be reasonably expected, while the factory 1:14 barrel would only shoot 52 gr match bullets to my satisfaction.
If you are concerned about the rate of twist that means you are considering a new barrel, so I'll tell you what I did with my .308. When I had it chambered I made up a dummy round with a 200 gr MK so that the bullet was seated so only the boat-tail was below the neck. This was sent to my gun smith who cut the chamber so the lead would allow for this long OAL. This additional powder capacity allows me to come within a hair of 2700 fps with that bullet from a 1:8 28" barrel. That's a far cry from the 2400 fps maximum listed in the loading manuals. Now, you might not get that velocity from a short barrel hunting rifle, but it will behave more like a .30/06 if you want to shoot heavy bullets. Before taking that step though, you want to make sure that your magazine will accept that long a cartridge.
If 220's are as heavy as you will load, then a 1:10 is probably the correct choice, in fact a 240 gr Woodleigh will also stabilize in a 1:10 barrel. For the naysayers who claim that a fast twist destroys light bullet accuracy, I was out a few weeks ago with my .308, and was hitting clay birds at 825 yards with 168 gr Nosler J-4's, but I haven't tried any long range shooting with lighter bullets from that barrel to say that accuracy would hold up with 155's. Based on my experience with fast twist barrels I think it will, but I haven't done it.
The bottom line is, I have discovered that I am limited by too slow a twist far more often than I am too fast a twist. My wife's .30/06 Husky has a 1:12 barrel, and that barrel will not stabilize 240 gr Woodleighs, but my 1:10 .30/06 Brno does. My Lilja 1:10 .243 will not stabilize the long 107 gr MK's, but a 1:7 would. My old 1:7 .222 shot every .224 bullet I loaded for it beyond what might be reasonably expected, while the factory 1:14 barrel would only shoot 52 gr match bullets to my satisfaction.
