Hogdons 6.5x55 160g H4831 load - 04/23/19
Last week I decided to load up a bullet I haven't shot in many years; the 6.5mm 160 grain Sierra SMP. I saw that Hodgdon has H4831 listed a max charge of 48.0 grains with a Hornady 160g showing 2,524 fps. That's decent velocity for a 160g bullet using the older Swede pressure limits. But 48.0 grains seems a rather...generous...amount of powder. But this is from Hodgdon, not "some guy" off of the Internet.
I loaded up a mini-Audette ladder starting at 43.8g and going up to 48.0g in 0.6gr increments. I took them to the range on Saturday morning to get an idea of velocity and potential accuracy nodes using a LabRadar chronograph. Unfortunately, I missed the reading on the first shot (43.8gr) due to a chronograph alignment issue. Which is too bad as the reading would have given me a heads up and more confidence on my second reading...
Shot #2 (44.4 gr) clocked at 2,557 fps. That gave me a pause as the max load of 48.0g was supposed to show 2,524 fps. At this point I didn't have enough information to determine if it was a bad chrono reading or if I was over-pressure.
Shot #3 (45.0gr) clocked at 2,598 fps and nearly locked the bolt up!
Obviously, continuing to shoot would be foolhardy.
I would like your opinions as to why you think my results are so different from Hodgdon's. I tried to keep as much the same as possible.
Hodgdon:
Brass: Winchester
Bullet: 160g Hornady RN
Primer: Wincheser WLR
COAL: 3.000"
Sized: Full-length?
Brass Life: New?
Distance from lands: Unknown
Mine:
Brass: Winchester
Bullet: 160g Sierra SMP
Primer: Wincheser WLR
COAL: 2.990"
Sized: Neck Sized (Lee Collet Die)
Brass Life: 4th Loading (not annealed)
Distance from lands: 0.008"
The is the first time this brass has been neck-sized with the LCD. The brass chambered smoothly with no noticeable resistance. The 2.990" COAL is what I've always used with my Reloder-22 loads. This is a factory CZ 550 American 6.5x55 SE. I've never found it to be tight chambered. This same batch of brass is used with my other standard loads and shows no undue pressure issues.
Is it just due to the differences in bullets? I wouldn't think there would be enough difference in bullets for this large of a discrepancy. Because I'm close to the lands?
I checked the latest Hornady, Sierra, and Lyman manuals.
Sierra didn't list a H4831 load.
Hornady has a recommended maximum of 42.3gr of H4831 @ 2.970".
Lyman lists a maximum of 46.0g of H4831 @ 3.000".
Is Hodgdon's data just a bit hot? Ideas?
Thanks.
I loaded up a mini-Audette ladder starting at 43.8g and going up to 48.0g in 0.6gr increments. I took them to the range on Saturday morning to get an idea of velocity and potential accuracy nodes using a LabRadar chronograph. Unfortunately, I missed the reading on the first shot (43.8gr) due to a chronograph alignment issue. Which is too bad as the reading would have given me a heads up and more confidence on my second reading...
Shot #2 (44.4 gr) clocked at 2,557 fps. That gave me a pause as the max load of 48.0g was supposed to show 2,524 fps. At this point I didn't have enough information to determine if it was a bad chrono reading or if I was over-pressure.
Shot #3 (45.0gr) clocked at 2,598 fps and nearly locked the bolt up!
Obviously, continuing to shoot would be foolhardy.
I would like your opinions as to why you think my results are so different from Hodgdon's. I tried to keep as much the same as possible.
Hodgdon:
Brass: Winchester
Bullet: 160g Hornady RN
Primer: Wincheser WLR
COAL: 3.000"
Sized: Full-length?
Brass Life: New?
Distance from lands: Unknown
Mine:
Brass: Winchester
Bullet: 160g Sierra SMP
Primer: Wincheser WLR
COAL: 2.990"
Sized: Neck Sized (Lee Collet Die)
Brass Life: 4th Loading (not annealed)
Distance from lands: 0.008"
The is the first time this brass has been neck-sized with the LCD. The brass chambered smoothly with no noticeable resistance. The 2.990" COAL is what I've always used with my Reloder-22 loads. This is a factory CZ 550 American 6.5x55 SE. I've never found it to be tight chambered. This same batch of brass is used with my other standard loads and shows no undue pressure issues.
Is it just due to the differences in bullets? I wouldn't think there would be enough difference in bullets for this large of a discrepancy. Because I'm close to the lands?
I checked the latest Hornady, Sierra, and Lyman manuals.
Sierra didn't list a H4831 load.
Hornady has a recommended maximum of 42.3gr of H4831 @ 2.970".
Lyman lists a maximum of 46.0g of H4831 @ 3.000".
Is Hodgdon's data just a bit hot? Ideas?
Thanks.