Home Forums Hunting & Shooting Ask The Gunwriters 6.5 SAUM Hype

George Gardner post on SH:

Im back in town and unthawed, the Icebreaker was a great time as usual. The Xtreme Hunter is just at its debut, Im not one to just throw a product at guys without a year of testing. Yes I have over 3400 rounds on my rifle now and its still shooting sub 1/2" Bryan Yeung on Team GAP shot one to 2800 and it was still in the 1/2 " range. This is proven. Its not a real secret its about Pressure!! The 308 runs at at pressures of 53000-58000 PSI I wanted to find a case that would make 3100 with a High BC Bullet at that same low low pressure. The Saum was wat we landed at with lots of testing. With a 140 JLK I could get 3080 FPS with only 53000 PSI I shot this load for a year, guys there are many to witness, I shot this at Lonestar, Snipershide Cup, PTS, Maammoth, and Nor-Cal I shot this at last years IceBreaker, and this years as well , with alot of practice in between, all on the same original Barrel. It still shoots great. The same load is now 3020 but with 63 grains of H1000 and the 130 Berger im getting 3180 in this same warn out Rifle with that group at 1157 to prove it still has some life. Guys this is Legit its about pressure!!!! This cartridge is Game Changing and the Xtreme Hunter is the only rifle a Guy needs in N America.

I have 2200 rounds through my 6.5 SAUM, and it's still shooting really good(sub 1/2"). I have ran her hard too.....just ask my buddies who've seen me shoot it a lot in the last 9 months.

My next build is going to be a heavy comp rifle in that chambering. Within a year we will have commercial brass for it. Until then, I'll try to wear out the 1200 pieces of brass I've prepped.

rifleman700,

Ah, the statement about the .308 running at 53,000 to 58,000 psi explains a lot. Don't know what ammo's used to create those relatively low pressures (as I noted above, the SAAMI maximum average pressure for the .308 is 62,000K), but the 6.5 SAUM at 55,000 or so would definitely create less heat than if loaded to normal .308 pressures.

Pat,

Who's going to make the brass?

I have a 700 action for the 7mm SAUM, set up to screw other barrels in and out. Have been very happy with the 7mm but will probably have to fool with the 6.5 as well.

Looney!

Or is that Gun Writer?

Or both!

I have a stainless NH model 70 in 300 WSM I bought a while back just because I thought I might want try this cartridge. I've not scoped or fired the rifle, it's just standing in the back of the safe.

This site has been by far the most expensive "free" place I've ever visited!

Brad,

They're not mutually exclusive--or even financially healthy....

All of our reloading data deals with peak pressure which is directly correlated to peak temperature.

Very seldom does one encounter any data or commentary about flame duration.

I submit that there is vast difference in the amount of throat erosion caused by 6.5 SAUM with a 140 gr bullet at 58,000 psi using IMR 3031 and the same cartridge/bullet/pressure combination using H1000.

While the 260 may be loaded to the same peak pressure as the 6.5 STW, the 260 will be loaded with a much quicker powder as well as less powder. The 260 will expose the bore to peak temperature for a shorter period with each shot. (microseconds shorter, but a large chunk of time when considered as a percentage)

It is all about the pressure curve.

Tag for future reference.

John,

I thought slow burning powders like H1000 were supposed to be used near max pressure, not 53k? Is there something different about H1000 or is the risk of secondary pressure excursion, um overblown?

Jason

Idaho Shooter,

The military research does contain some info about flame duration, as I recall. They even came to the conclusion that an eroded throat tends to cause even faster erosion, because some of the hot gas circulated in the rough area, instead of flowing more directly down the bore.

4th Point,

In general any smokeless powder does burn more consistently within the general range its designed for, but a case FULL of powder will burn consistently even if the ideal pressure isn't reached.

Don't know exactly what you mean by a secondary pressure excursion.

Yes, but is the 6.5SAUM actually being run at 55k psi. In my rather rudimentary calculations, there is no way it would get those velocities at that pressure.

I did some calculating and suspect it would with enough barrel length. Or at 58,000, the upper end of the .308 pressure range quoted.

Explain why I have a box of 50 6.5 SAUM cases that have been loaded and fired 18 times, produce 3100fps with a 139gr bullet and still have snug primer pockets.....amazing how many "experts" there are out there with strong opinions on subjects they have zero experience with.

Do you have any first hand experience with the said cartridge?

Maybe you should drive up here in April and school all of us 6.5 SAUM shooters on how our rifles should run....

I would be elated to get 3000 fps from a 140 6.5 in a sa at 55K.

Pat,

What barrel length on your rifle?

24" Bartlein 1-8.7"5R

Looks I'm going to have to go barrel shopping....

I run the identical rifle as Pat, except mine is serial number 3.

I get 3140 with the 140 amax here in the 307. 61.5 grains H1000

200yard zero









I will be at Pats in April.... All the nay Sayers can show up and see the facts in person