6.5 Sherman LA loading

[dok7mm]

Update: I managed to locate 7- 1# bottles of N-570, cheap because the guy just didn't like the big grains. Lucky me.

Anyway, I loaded up some 150 Matrix for pressure tests @ .030" off, with the N-570, with .5 gr. intervals. Coolest day in months, @ 75*, heavy cloud cover and rain.
62.0 - 3025 fps
62.5 - 3040
63.0 - 3064
63.5 - 3102
64.0 - 3138
64.5 - 3145
65.0 - 3165

I kept expecting pressure every shot, but it never came. There was the faintest smear on 65.0, no bolt lift signs. 26" Bart 5R 8 twist, 648 rds. I was surprised the velocity matched my 140/Retumbo load. Velocities (LabRadar) are the average of 2 targets, one @ 100 and another at 200, same charges. The longer range was closed because of rain.
ADD. 7th firing on 280 Norma brass.

 

[ramrod79]

That's awesome speed I bet you would do good with 160s that 65 is 1/2 under my 140 berg load.
I bet you could push 160 at 3050 no prob.

 

[dok7mm]

That's awesome speed I bet you would do good with 160s that 65 is 1/2 under my 140 berg load.
I bet you could push 160 at 3050 no prob.

I have 400 160s, so I might try them. Not sure the 160 would open up like 142 & 150, at long range. Was told the jacket is thicker. ????

 

[ramrod79]

That is what's I had heard so I never bothered. I wonder if Annealing or buying the bonded ones would help. I am switching to a 270 Sherman with the 170 for that reason unless someone tells me different.
I know when I talked with Rich he mentioned 150 maybe the best choice but there not enough difference for me to switch my 140 load to the 150s. If Berger would hurry up so I would not have to do a barrel change.

 

[coance]

Finally found some 150 SMK'S in stock. Will be working up a load with them as soon I get them.Has anyone tried them yet?

 

[ramrod79]

I used MK in my 260 and shot a deer at 350 pencil hole through and through although he only went 20 ft I quit using after that.

 

[coance]

We're they 150's or 142's

 

[ramrod79]

I used 142 and while they did job I wasn't happy with pin hole so I quit using went to Berger never looked back.
Matrix 250 are supposed to work real well 160s are still in air not much on here at extended range performance.

 

[coance]

Which Berger's do you run? Targets, Hybrids or hunters

 

[ramrod79]

VLD Hunters

 

[coance]

Finally got the 150 smk's in and did some testing. 58.5 grains of RL23 is my limit. It easily got 3150+ fps. Will start checked ng accuracy next. I have some loads ready from 56 to 58.5. I ran it up to 60.5 but pressure got way high so I won't go back that high.
Will add more when I get to shoot these.

 

[coance]

Got a chance to shoot the 56 to 58.5 loads this weekend. 57 and 57.5 were both under MOA while the rest were close to it . Non are anywhere close to the accuracy of my fireforming rounds.They were 56 grains of RL 23 pushing 142 SMK.
I am thinking the RL 23 may not work quite as well with these heavier 150's. Thinking of trying a seating depth change and possibly Retumbo. Any thoughts?

 

[dok7mm]

I'd run a comprehensive seating depth test, prior to changing powders. You should be able to tighten it up. That said, I lean towards the Hodgdon Extreme powders, so I like Retumbo very much.

 

[Korhil78]

I would try H1000, Retumbo or RL26. For your weight class of bullets, RL23 is a little too fast burning.

I use Retumbo and am averaging 3205 fps with Retumbo and 140 Gr Berger. Very good accuracy as well.