6.5 SS (Sherman Shortmag) Q@A

[Wesley Erdle]

Ok guys (and Rich).....now that the 6.5 SS and SST have been out for quite some time now what is everyone getting for barrel life? I know it varies depending on many factors but get me in the ball park? Very interested in building one of these or a SAUM. Thanks.

 

[LRJunkie]

You should be able to expect a 20fps gain in velocity per inch of barrel length...a good educated guess for a 26" barrel's velocity should at least be 40fps more velocity than the averages I previously listed with the powder charges. It's quite possible that your barrel could generate a little more than the 20fps per inch gain in velocity, per inch of barrel length that I have experienced too. You never really know exactly how a barrel will perform until you shoot it.

Do you happen to have the H20 volume in weight for a fired 6.5 SST case ?

 

[shinbone]

(bringing this old thread back up)

I've got a Kimber Montana in 270WSM. I think the 270WSM is a great round. But, I want to rebarrel to either a 6.5SS or a 6.5WSM just for the fun of it.

How does the 6.5SS compare to the 6.5WSM? Why choose one over the other?

 

[parshal]

There is a comparison earlier I. This thread, I think.

I have both. The WSM is longer. The SS more easily fits in an SA.

Performance-wise they're the same.

 

[elkaholic]

There is a comparison earlier I. This thread, I think.

I have both. The WSM is longer. The SS more easily fits in an SA.

Performance-wise they're the same.

+1 and ss has better brass and better barrel life. Fits in a short action.

 

[adamjp]

What pressure traces exist to document the pressures generated?

I agree with the idea of a long neck and slightly sharper shoulder improving throat life. If pressure is the same, then barrel life is directly influenced by heat generated by the explosion. A hot barrel wears faster than a cool barrel, a high pressure barrel wears faster than a low pressure one. Working to heat sink the throat area with the longer case neck, and working to give more direction to the pressure coming from case which is parallel to the case may also improve throat life.

I cannot agree with case design offering 'efficiency' which allows greater velocities than cases with slightly larger capacities at same or lower pressures. In short, velocity is determined by case capacity, pressure and powder.
If powder is the same (charge weight variance only) then capacity and pressure are the determinants of velocity.

To get 3200fps+ from 140gn bullets with a capacity just under the 6.5 SAUM the pressure is going to be higher than from the 6.5 SAUM case.

How much higher is the pressure?

 

[elkaholic]

What pressure traces exist to document the pressures generated?

I agree with the idea of a long neck and slightly sharper shoulder improving throat life. If pressure is the same, then barrel life is directly influenced by heat generated by the explosion. A hot barrel wears faster than a cool barrel, a high pressure barrel wears faster than a low pressure one. Working to heat sink the throat area with the longer case neck, and working to give more direction to the pressure coming from case which is parallel to the case may also improve throat life.

I cannot agree with case design offering 'efficiency' which allows greater velocities than cases with slightly larger capacities at same or lower pressures. In short, velocity is determined by case capacity, pressure and powder.
If powder is the same (charge weight variance only) then capacity and pressure are the determinants of velocity.

To get 3200fps+ from 140gn bullets with a capacity just under the 6.5 SAUM the pressure is going to be higher than from the 6.5 SAUM case.

How much higher is the pressure?

We're actually getting very good barrel life.......next
At very good velocities

 

[adamjp]

I think we all understand that you are claiming good barrel life at good velocities.

What I asked is how much higher is the pressure?

Or another way, What do the pressure traces show?

Surely as a person who is in business to sell cartridges, dies and reamers to people you have pressure testing equipment (like a piezo strain gauge) to ensure that reasonable loads in your cartridges are safe in common action/barrel combinations they would be built upon?

 

[dirtytough]

This is starting to sound like the 7SS thread.

 

[parshal]

I have no pressure tested loads in my 6.5 WSM, 22 or 6 Creed. I have to load the old fashioned way and look for pressure signs. The SS loads developed the same way have near identical and, at times, have exceeded that of the WSM. Do they have higher pressure? Who knows. But, they're developed using the same method as all my other wildcats so I don't worry about.

 

[lancetkenyon]

No fancy equipment here either, I am a blue collar guy.

But I feel I am a fairly experienced hand-loader. I am meticulous about looking for signs of pressure.

There are so many variables, it is nearly impossible to say what an actual baseline written max load/velocity is across the board. Unless you are talking a "lawyer load".

I relly don't care about comparing the Sherman lines to either RSAUMs, WSMs, Ackleys, etc. The Sherman lines work fantastically. Fit better in a short action than anything except maybe a WSSM round, cycle smoothly, and produce numbers that are very desirable. Have great brass available, are usually chambered by the better gunsmiths, and loaded by more experienced hand-loaders, which helps the accuracy curve.

If it helps, I get:
2976fps w. 156 Elite in a 20" 1:7.5" Proof (up to 3009)
3168fps w. 144 Hyb in a 26" 1:7.5" Proof (up to 3188 in a notoriously slow rifle)
3113fps w. 150 SMK in a 25.5" 1:8" Bartlein (up to 3165)

These are all higher charge weight loads, but no signs of pressure.

 

[elkaholic]

I think we all understand that you are claiming good barrel life at good velocities.

What I asked is how much higher is the pressure?

Or another way, What do the pressure traces show?

Surely as a person who is in business to sell cartridges, dies and reamers to people you have pressure testing equipment (like a piezo strain gauge) to ensure that reasonable loads in your cartridges are safe in common action/barrel combinations they would be built upon?

NEXT!

 

[H59]

I can vouch for the barrel life being quite good. I'm on my 3rd barrel now and was able to get 2000 plus from my first one(bartlien m24-1/8- 26") didn't run it hard at all shot mostly 147eld-m at 2940fps - 2960fps...now that barrel was shot out when I pulled it but I hadn't had much fps fall off but groups were opening up. The 2nd barrel was another bartlien but a heavy varmint 1/8 twist - 24" I ran it hard. Shot back to back 10 shot groups etc.Getting 3050 - 3070fps with 147eld-m's...got little over 1600 when groups started opening up and velocity was steadily lowering-while shooting the same load I had been running i was getting b/n 3010fps & 3020fps... It's a good chamber design and with the new heavy high b.c. bullets out there today it's a solid choice for running them with good velocity and consistently accurate platform to do it, and for a variety of use's...

 

[elkaholic]

I can vouch for the barrel life being quite good. I'm on my 3rd barrel now and was able to get 2000 plus from my first one(bartlien m24-1/8- 26") didn't run it hard at all shot mostly 147eld-m at 2940fps - 2960fps...now that barrel was shot out when I pulled it but I hadn't had much fps fall off but groups were opening up. The 2nd barrel was another bartlien but a heavy varmint 1/8 twist - 24" I ran it hard. Shot back to back 10 shot groups etc.Getting 3050 - 3070fps with 147eld-m's...got little over 1600 when groups started opening up and velocity was steadily lowering-while shooting the same load I had been running i was getting b/n 3010fps & 3020fps... It's a good chamber design and with the new heavy high b.c. bullets out there today it's a solid choice for running them with good velocity and consistently accurate platform to do it, and for a variety of use's...

Real data! No need to believe that Sherman dude.