Can you rechamber a .270 WSM to 6.8 by shortening the shank/chamber end and running a finish reamer?

Wilderness Blacktail · Tuesday at 7:38 PM

ObiJohn said:
From what I understand a .270 WSM with 175 gr bullets will not fit in a short action's mag box or feed from it, while 6.8 Western with long bullets will fit and feed (isn't that the reason they developed the 6.8 in the first place?).

I originally asked because I've seen several M70 Classic rifles in .270 WSM that I've thought of picking up, but no point in rechambering a 1:10" barrel.

A Good way to get a visual reference is to look at a saami spec 260 remington with a 140gr n up bullet and then look at the 6.5 Creedmoor with the same bullet. They both fit and the bigger case can run it faster all else being equal.

The 6.8W and 6.5CM are shorter and so more ideally designed for that combination but it works in either. There are of course specific bullets that may not fit at a certain COL in one case, magazine or chamber but thats just the way things go.

The M70 win has a 3" magazine if im not mistaken. My 270WSM XPR has a 2.9sumthin mag if i recall. I can check.

Wilderness Blacktail · Tuesday at 7:46 PM

ObiJohn said:
From what I understand a .270 WSM with 175 gr bullets will not fit in a short action's mag box or feed from it, while 6.8 Western with long bullets will fit and feed (isn't that the reason they developed the 6.8 in the first place?).

I originally asked because I've seen several M70 Classic rifles in .270 WSM that I've thought of picking up, but no point in rechambering a 1:10" barrel.

I think the real reason they developed it is they didnt wanna confuse people with two loadings of 270wsm. As in a 1:10, 2.8" combo and a long throated 1:8 twist
combo.
Aaand new cartridges are opportunity for new customers and many newer enthusiasts may not know that a longer ie 2.95" throated 270wsm with quick twist is still more capable than a smaller case with same throat/barrel specs, so the 6.8 seduces them with all its moderness.

JAYgs8163 · Tuesday at 8:25 PM

Wilderness Blacktail said:
I think the real reason they developed it is they didnt wanna confuse people with two loadings of 270wsm. As in a 1:10, 2.8" combo and a long throated 1:8 twist
combo.
Aaand new cartridges are opportunity for new customers and many newer enthusiasts may not know that a longer ie 2.95" throated 270wsm with quick twist is still more capable than a smaller case with same throat/barrel specs, so the 6.8 seduces them with all its moderness.

BINGO! Winner Winner Chicken Dinner!

Hence, this! 3.080 Coal 270WSM long action .200

Wilderness Blacktail · Tuesday at 11:47 PM

Thats a nice lookin round. What bullet? Speed?

FEENIX · Wednesday at 4:18 AM

Wilderness Blacktail said:
What bullet?

It looks like McGuireBallistics Copper Rose.

JAYgs8163 · Wednesday at 5:02 AM

22" 7Twist barrel
McGuire Ballistics Copper Rose
Grain Weight: 128
Estimated Ballistic Coefficient: G1 .580
Projectile Length: 1.390
I ran it up to 66 grains H4831SC with no pressure signs and 3220 FPS. Still in load development stages for this rifle as just got my ADG Brass. Also waiting for McGuires new 145/150 to come out.

FEENIX · Wednesday at 5:27 AM

JAYgs8163 said:
22" 7Twist barrel
McGuire Ballistics Copper Rose
Grain Weight: 128
Estimated Ballistic Coefficient: G1 .580
Projectile Length: 1.390
I ran it up to 66 grains H4831SC with no pressure signs and 3220 FPS. Still in load development stages for this rifle as just got my ADG Brass. Also waiting for McGuires new 145/150 to come out.

Sam did an excellent job with those bullets, and I like how he promotes them. I am looking forward to your load development and successful harvests.

ObiJohn · Wednesday at 9:49 AM

JAYgs8163 said:
22" 7Twist barrel
McGuire Ballistics Copper Rose
Grain Weight: 128
Estimated Ballistic Coefficient: G1 .580
Projectile Length: 1.390
I ran it up to 66 grains H4831SC with no pressure signs and 3220 FPS. Still in load development stages for this rifle as just got my ADG Brass. Also waiting for McGuires new 145/150 to come out.

I assume from your posts that this will not fit in a typical short action R700 clone or post-64 Win M70 action magazine/mag box (single-load into the action only), but will fit in a pre-64 M70 '06 length action or R700/M70 long action... correct?

With a 24" barrel you should be getting well over 3,300 ft/sec. That should be one flat-shooting, hard-hitting rifle. But... this is basically a 6.8 Western with the same bullet out of the same barrel length with about 100 yards more range... correct?

JAYgs8163 · Wednesday at 10:16 AM

1)Correct
2)I don't have a 6.8 to test but with additional Freebore in a 270WSM and using in a long action as I believe I mentioned, the 270WSM should have more case volume.

Same reason why most build SAUMs on a long action. Sorry if I wasn't clear in my prior posts that I built this on a long action, I thought I had. I think I also mentioned using a 22" barrel. 3300 is definitely attainable with 130 grain Cup/Core bullets and some Monos in my 270WSM. I've only begun with load development in my rifle so I've got a lot of other projectiles to try. I can't speak to the 6.8 loads or load data. I'll be sure to post my results as I move on though.

Wilderness Blacktail · Wednesday at 7:25 PM

FEENIX said:
It looks like McGuireBallistics Copper Rose.

I thot so as well.

Wilderness Blacktail · Wednesday at 7:35 PM

JAYgs8163 said:
...
Same reason why most build SAUMs on a long action. Sorry if I wasn't clear in my prior posts that I built this on a long action, I thought I had. I think I also mentioned using a 22" barrel. 3300 is definitely attainable with 130 grain Cup/Core bullets and some Monos in my 270WSM. I've only begun with load development in my rifle so I've got a lot of other projectiles to try. I can't speak to the 6.8 loads or load data. I'll be sure to post my results as I move on though.

Im curious to hear what speeds you end up with for sure. With my standard 270WSM i couldnt get 130 monos to 3300 with any accuracy. I finally found it likes faster powders and with the 4350s such is doable.
The C.R's are very intruiging to me and I plan to start trying them in various rifles in the new year.

Can you rechamber a .270 WSM to 6.8 by shortening the shank/chamber end and running a finish reamer?

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