Gunsmithing 6.5 wsm Twist rate
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Re: 6.5 wsm Twist rate
Easy now, Friend!
You're talking about using a <span style="font-weight: bold">way overbore case</span> based on the WSM brass <span style="font-weight: bold"><span style="font-style: italic">when necked down to .264 caliber</span></span>. With a 1:8 twist barrel, You will blow up bullets that can't take that level of excessive spin. Not to mention that even with a 30 inch barrel, you won't max out on your top bullet speed if you use the slower burning magnum type powders.
To put it bluntly, you are going to be mixing the extremes by combining the 6.5mm projectiles with the WSM brass.
The 6.5mm WSM holds <span style="font-weight: bold">79.50 grains of H2O</span>, that's just shy of the .264 Winchester Magnum's 82 grains <span style="font-weight: bold"><span style="font-style: italic">which was designed to push the smaller 6.5mm bullets, not the big heavy ones.</span></span> The WSM's smaller cousin, the 6.5mm Rem SAUM, which is also overbore for the .264 caliber barrels, holds <span style="font-weight: bold">72 grains</span>. The old 6.5mm Remington Magnum, one of the first short action magnums to hit the market decades ago, holds <span style="font-weight: bold">68 grains of H2O</span> as does the tried and trued 6.5-06 (which is also known to be notoriously overbore).
Finally, we step down to the 6.5-284 Winchester/Norma cartridges. These fat boys that are re-nowned as barrel burners, hold 66 grains and that fact is key. Why? Because the 6.5-284 will push the Berger 140 gr VLD's at and above 3200 fps.
If you just have to go this route of speed to the extreme, I would recommend that you look at a slightly smaller case than the WSM.
If you haven't bought brass and dies yet, I would advise you to seriously take a step back and look at what your overall goal is. How much faster than 3200 fps do you need to push a 140 grain Berger VLD? How much faster than 3200 fps do you think you can actually push a 140 grain Berger VLD before it blows up?
You also need to strongly consider how long is the barrel going to be? With these magnum cases, you will just be burning a lot more powder past the muzzle if you don't have a 30 inch barrel or longer.
By comparison, the .260 Remington (a .308 necked down to 6.5mm) doesn't need a long barrel, but if you push the shoulders forward and make it a .260AI (still much smaller than the 6.5-284) and load the slower powders like 4831sc, you'll see velocity gains even past 26 inches of tube.
Yeah, been there done that.
So, be careful what you ask for. At those extemely fast speeds you will most likely be able to overspin the 140 grain bullets using anything faster than a 1:9 twist barrel. Get yourself one heck of a long tube, the 30 inch palma length is a good starting point and start with a smaller case. I think you'll reach the bullets self destruction speed very quickly.
And if the bullet never makes it to the target, what's the point?
Easy now, Friend!
You're talking about using a <span style="font-weight: bold">way overbore case</span> based on the WSM brass <span style="font-weight: bold"><span style="font-style: italic">when necked down to .264 caliber</span></span>. With a 1:8 twist barrel, You will blow up bullets that can't take that level of excessive spin. Not to mention that even with a 30 inch barrel, you won't max out on your top bullet speed if you use the slower burning magnum type powders.
To put it bluntly, you are going to be mixing the extremes by combining the 6.5mm projectiles with the WSM brass.
The 6.5mm WSM holds <span style="font-weight: bold">79.50 grains of H2O</span>, that's just shy of the .264 Winchester Magnum's 82 grains <span style="font-weight: bold"><span style="font-style: italic">which was designed to push the smaller 6.5mm bullets, not the big heavy ones.</span></span> The WSM's smaller cousin, the 6.5mm Rem SAUM, which is also overbore for the .264 caliber barrels, holds <span style="font-weight: bold">72 grains</span>. The old 6.5mm Remington Magnum, one of the first short action magnums to hit the market decades ago, holds <span style="font-weight: bold">68 grains of H2O</span> as does the tried and trued 6.5-06 (which is also known to be notoriously overbore).
Finally, we step down to the 6.5-284 Winchester/Norma cartridges. These fat boys that are re-nowned as barrel burners, hold 66 grains and that fact is key. Why? Because the 6.5-284 will push the Berger 140 gr VLD's at and above 3200 fps.
If you just have to go this route of speed to the extreme, I would recommend that you look at a slightly smaller case than the WSM.
If you haven't bought brass and dies yet, I would advise you to seriously take a step back and look at what your overall goal is. How much faster than 3200 fps do you need to push a 140 grain Berger VLD? How much faster than 3200 fps do you think you can actually push a 140 grain Berger VLD before it blows up?
You also need to strongly consider how long is the barrel going to be? With these magnum cases, you will just be burning a lot more powder past the muzzle if you don't have a 30 inch barrel or longer.
By comparison, the .260 Remington (a .308 necked down to 6.5mm) doesn't need a long barrel, but if you push the shoulders forward and make it a .260AI (still much smaller than the 6.5-284) and load the slower powders like 4831sc, you'll see velocity gains even past 26 inches of tube.
Yeah, been there done that.
So, be careful what you ask for. At those extemely fast speeds you will most likely be able to overspin the 140 grain bullets using anything faster than a 1:9 twist barrel. Get yourself one heck of a long tube, the 30 inch palma length is a good starting point and start with a smaller case. I think you'll reach the bullets self destruction speed very quickly.
And if the bullet never makes it to the target, what's the point?
Re: 6.5 wsm Twist rate
Ranger said more or less what I was thinking, but better than I would have...
Ranger said more or less what I was thinking, but better than I would have...
Re: 6.5 wsm Twist rate
A 8.5 will do it, an 8 will do it....I dunno on a 9. Life is not always about efficiency. Do not expect match bullets to hold up on critters up close....I doubt they will pop in mid air.
A 8.5 will do it, an 8 will do it....I dunno on a 9. Life is not always about efficiency. Do not expect match bullets to hold up on critters up close....I doubt they will pop in mid air.
Re: 6.5 wsm Twist rate
You should be able to use a 1 in 8.5 twist for the bullets you mention.
I think you should buy them by the bucket because a 6.5 WSM could very well be a champion barrel burner.
You should be able to use a 1 in 8.5 twist for the bullets you mention.
I think you should buy them by the bucket because a 6.5 WSM could very well be a champion barrel burner.
Re: 6.5 wsm Twist rate
Someone on here as done it, cant remember the name. Mulehunter or something close to it??? He seems to like it, last time I talked to him about it.
Someone on here as done it, cant remember the name. Mulehunter or something close to it??? He seems to like it, last time I talked to him about it.
Re: 6.5 wsm Twist rate
If you're indeed going to make a 6.5WSM and 3200-3300fps is your goal, a 9 or 8.5 twist would work. 8-twist would be risking bullet blowup at those velocities.
If you're indeed going to make a 6.5WSM and 3200-3300fps is your goal, a 9 or 8.5 twist would work. 8-twist would be risking bullet blowup at those velocities.
M
milo 2.0
Guest
Re: 6.5 wsm Twist rate
The 9 twist works, The 8.5 twist Krieger sounds good too.
I have a friend with 6.5WSM, shoots Norma 130's at 3350, kickass.
Have another that has a 6.5 SAUM, he shoots 140 Bergers at 3350ish rate, the saum is a better case.
Not wanting to piss off a Ranger, but I don't want to be around anyone getting 3200fps out of a 6.5x284 with 140's. I got 3080fps out of mine using 58.7gr of Norma MRP-2, a great powder, and a 130gr Norma. That was horsing it and the barrel-throat was gone at 1100rds.
Build it, you will love it.
Miles
The 9 twist works, The 8.5 twist Krieger sounds good too.
I have a friend with 6.5WSM, shoots Norma 130's at 3350, kickass.
Have another that has a 6.5 SAUM, he shoots 140 Bergers at 3350ish rate, the saum is a better case.
Not wanting to piss off a Ranger, but I don't want to be around anyone getting 3200fps out of a 6.5x284 with 140's. I got 3080fps out of mine using 58.7gr of Norma MRP-2, a great powder, and a 130gr Norma. That was horsing it and the barrel-throat was gone at 1100rds.
Build it, you will love it.
Miles
Re: 6.5 wsm Twist rate
milo-2,
no worries about pissing me off. Like I said, "been there, done that". Screaming fast and ran out of room in the case. Just saw the very faintest of pressure signs at the highest speeds. Would NEVER recommend someone trying to duplicate this. Then again, this was chronied at about 2000 feet above sea level.
One big truth you said, for using short actions, the Remington Short Action Ultra Magnum (SAUM) brass gives you better bullet seating choices than the WSM brass. Better seating choices usually helps to increase accuracy.
milo-2,
no worries about pissing me off. Like I said, "been there, done that". Screaming fast and ran out of room in the case. Just saw the very faintest of pressure signs at the highest speeds. Would NEVER recommend someone trying to duplicate this. Then again, this was chronied at about 2000 feet above sea level.
One big truth you said, for using short actions, the Remington Short Action Ultra Magnum (SAUM) brass gives you better bullet seating choices than the WSM brass. Better seating choices usually helps to increase accuracy.
M
milo 2.0
Guest
Re: 6.5 wsm Twist rate
Ranger,
What powder were you using to get that velocity??
N570 is the only thing I can think of. We are at 4760 here, if I came down to 2000 I'd be lost.
Miles
Ranger,
What powder were you using to get that velocity??
N570 is the only thing I can think of. We are at 4760 here, if I came down to 2000 I'd be lost.
Miles
Re: 6.5 wsm Twist rate
I built a 6.5 WSM using a PAC-NOR 1-8" twist on a Savage WSM action and shot 130's and above only and never blew up a bullet. It was a great round until about 500 rounds and then the barrel went bad. If I did it again I would try getting the barrel treated with the Nitride process as this would be a great test case to see if you can get better life out of a true barrel burner.
You might want to get two barrels chambered up at the same time if you intend on shooting it much.
wade
I built a 6.5 WSM using a PAC-NOR 1-8" twist on a Savage WSM action and shot 130's and above only and never blew up a bullet. It was a great round until about 500 rounds and then the barrel went bad. If I did it again I would try getting the barrel treated with the Nitride process as this would be a great test case to see if you can get better life out of a true barrel burner.
You might want to get two barrels chambered up at the same time if you intend on shooting it much.
wade
Re: 6.5 wsm Twist rate
I have alot of time behind a 6.5 WSM. With an 8 twist barrel i have pushed 140 Bergers to 3250 without the bullet coming apart. Benchmark makes an 8.5 twist and an 8 twist. Depending on barrel length and expected velocities you are after both would work fine. I would not bother with the 9 twist. Either the 8 or 8.5 would be fine. If you want to shoot the 130's i would suggest the 8.5 twist.
chasing the lands i got 950 out of mine Nitrided.
we have a nice reamer set up for the 6.5 using 140 bergers if interested give Benchmark a call. They can have it Nitrided for you also.
I have alot of time behind a 6.5 WSM. With an 8 twist barrel i have pushed 140 Bergers to 3250 without the bullet coming apart. Benchmark makes an 8.5 twist and an 8 twist. Depending on barrel length and expected velocities you are after both would work fine. I would not bother with the 9 twist. Either the 8 or 8.5 would be fine. If you want to shoot the 130's i would suggest the 8.5 twist.
chasing the lands i got 950 out of mine Nitrided.
we have a nice reamer set up for the 6.5 using 140 bergers if interested give Benchmark a call. They can have it Nitrided for you also.
Re: 6.5 wsm Twist rate
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MuleHunter</div><div class="ubbcode-body">I have alot of time behind a 6.5 WSM. With an 8 twist barrel i have pushed 140 Bergers to 3250 without the bullet coming apart. Benchmark makes an 8.5 twist and an 8 twist. Depending on barrel length and expected velocities you are after both would work fine. I would not bother with the 9 twist. Either the 8 or 8.5 would be fine. If you want to shoot the 130's i would suggest the 8.5 twist.
chasing the lands i got 950 out of mine Nitrided.
we have a nice reamer set up for the 6.5 using 140 bergers if interested give Benchmark a call. They can have it Nitrided for you also. </div></div>
and that is as rock solid an answer you can get! Great post, MuleHunter!
<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MuleHunter</div><div class="ubbcode-body">I have alot of time behind a 6.5 WSM. With an 8 twist barrel i have pushed 140 Bergers to 3250 without the bullet coming apart. Benchmark makes an 8.5 twist and an 8 twist. Depending on barrel length and expected velocities you are after both would work fine. I would not bother with the 9 twist. Either the 8 or 8.5 would be fine. If you want to shoot the 130's i would suggest the 8.5 twist.
chasing the lands i got 950 out of mine Nitrided.
we have a nice reamer set up for the 6.5 using 140 bergers if interested give Benchmark a call. They can have it Nitrided for you also. </div></div>
and that is as rock solid an answer you can get! Great post, MuleHunter!
