6.5 saum

[elkaholic]

Rich a 270 has the same shoulder as a 30-06 but the 270 has a longer neck at 2.540" the 06 case length is 2.494" a 280rem has the shoulder moved forward so it can not be chambered in a 270 or 30-06

280 rem and 270 win have the same case length 2.540" but the 280 rem has the shoulder pushed forward .050"

That is correct! I was thinking of the 280. It's not like I don't measure this stuff about every other day for my Sherman, but my brain is getting aged like a fine cheese

 

[lowdowndirtybugger]

I went with a 6.5 saum match chamber ( .188 fb) .
Loaded .08 off the lands with 140 eldm
1 in 8 twist mcgowen barrel nitride by controlled thermal technology.
I ran into 2 nodes with h1000.
One at 58.5 grains sank 5 bullets into one ragged hole velocity at 3045
The next at 60.5 again 5 shots in one ragged hole velocity 3175.
I was able to get 3200 with 61 grains and 3220 at 61.4 but the groups opened to 5/8"
I think I'm going with the 58.5 grain load as my go to load. This should give decent barrel life and is still smoking fast

 

[MTHunt]

I went with a 6.5 saum match chamber ( .188 fb) .
Loaded .08 off the lands with 140 eldm
1 in 8 twist mcgowen barrel nitride by controlled thermal technology.
I ran into 2 nodes with h1000.
One at 58.5 grains sank 5 bullets into one ragged hole velocity at 3045
The next at 60.5 again 5 shots in one ragged hole velocity 3175.
I was able to get 3200 with 61 grains and 3220 at 61.4 but the groups opened to 5/8"
I think I'm going with the 58.5 grain load as my go to load. This should give decent barrel life and is still smoking fast

I was just looking at the 6.5 saum match chamber print from James at Northland. Thinking of going with it as well was wondering if I was still going to be able to mag feed from wsm accurate mags.. I was going to go with ELD-x or Berger Elites.. Want to build up a good long range hunting rifle and try to stay under 10 lbs.

 

[Wind Gypsy]

I was just looking at the 6.5 saum match chamber print from James at Northland. Thinking of going with it as well was wondering if I was still going to be able to mag feed from wsm accurate mags.. I was going to go with ELD-x or Berger Elites.. Want to build up a good long range hunting rifle and try to stay under 10 lbs.

Going off rough memory here but I'd guess you would be around 2.940 COAL with 140 ELD ms and just under 3" with berger 140 hybrids touching lands.

 

[MTHunt]

Going off rough memory here but I'd guess you would be around 2.940 COAL with 140 ELD ms and just under 3" with berger 140 hybrids touching lands.

Thats what i was hoping for.. Thanks.. Now to start scrapping money together to get a mag short action.

 

[lowdowndirtybugger]

Gap has a new reamer/chamber that looks to be a winner.
It has .153 free bore. This will fit any of the current long range bullets, still fit the mag and will shoot at lower pressure than the .081 chamber.
The .188 chamber I have maxes out the mag just into the lands with 140 eldm.

I adjusted the seating of my 61.4 grain load and was able to put 12 rounds in 1 hole

 

[stxhunter260ai]

.153? The last time I talked with them (about a month ago)they suggested a .120. Why do they keep changing the freebore dimensions?

 

[elkaholic]

Gap has a new reamer/chamber that looks to be a winner.
It has .153 free bore. This will fit any of the current long range bullets, still fit the mag and will shoot at lower pressure than the .081 chamber.
The .188 chamber I have maxes out the mag just into the lands with 140 eldm.

I adjusted the seating of my 61.4 grain load and was able to put 12 rounds in 1 hole

Without an increased length mag box, I guarantee that a 6.5 SAUM with a .153" throat will not fit unless the bullets are jumping a long ways and/or it is not taking up case capacity......Rich

 

[lowdowndirtybugger]

Some of the newer bullets have longer bearing surfaces causing pressure spikes in shorter throats. Or at least that's what George was saying about it.
Their normal throat is now the .120. .081 is only available by special order and .153 is the new suggestion.
Personally I like as much bearing surface in the throat as possible.

 

[MTHunt]

I went with a 6.5 saum match chamber ( .188 fb) .
Loaded .08 off the lands with 140 eldm
1 in 8 twist mcgowen barrel nitride by controlled thermal technology.
I ran into 2 nodes with h1000.
One at 58.5 grains sank 5 bullets into one ragged hole velocity at 3045
The next at 60.5 again 5 shots in one ragged hole velocity 3175.
I was able to get 3200 with 61 grains and 3220 at 61.4 but the groups opened to 5/8"
I think I'm going with the 58.5 grain load as my go to load. This should give decent barrel life and is still smoking fast

With the match chamber I am still trying to figure out how to read a reamer print and such, so with it having a neck of .2975 least the print I have that's what it is.. Would that be a turn or no turn neck? Doesn't say on the print that I can see..

 

[Wind Gypsy]

The .153 came with the new 147s and could be long if you want to shoot JLKS.

 

[lowdowndirtybugger]

With the match chamber I am still trying to figure out how to read a reamer print and such, so with it having a neck of .2975 least the print I have that's what it is.. Would that be a turn or no turn neck? Doesn't say on the print that I can see..

No turn.
In my experience with the same reamer turning to .0145 still shows better results than no turn. Neck tension or something

 

[Wind Gypsy]

See below from George Gardner. I'm not sure if they settled on .145 or longer .153 for the longer bullets. I know friend who shoots and works for GAP had his comp gun built with .153.

Mag feeding aside, my x47 has .180+ freebore and is a bit long for 140 jlks and about perfect for 140 ELDm.

 

[Wind Gypsy]

No turn.
In my experience with the same reamer turning to .0145 still shows better results than no turn. Neck tension or something

Yep, standard .2964 neck is for hornady 4s brass and turned rem or norma. Gaps "no turn" reamer was .298 but still required turning most of the time.