Thread: 165 gr ssts for my 308 m77

Originally Posted by bjp

Get good correlation in GRT (Gordons Reloading Tool) between your loads and measured velocities assuming a 2.80" COAL (GRT = 2645 fps). It shows hitting around 58k psi at 43.0g, and just over 60k psi at 43.5g. You might be able to get a little more speed, but it also might be at the expense of case life. Though at least brass is readily available for 308.

If you are happy enough with velocities, have you measured the max. COAL for your cartridge in this rifle? You could try adjusting jump to lands to see if things tighten up - though there appears to be no significant difference in the 42-43.5gn range. You would need to start shooting larger groups to do any real analysis. But it all looks good enough to hunt with!

Yeh im real happy with 1st attempts at loading.
Gonna play around in that 42-43 range. Was abit rushed at end so next time it'll be going in with a member or headed to a private range and taking more time!! Fell like I need an ogive comparator instead of measuring col as a coulpe of the bolt closes felt tighter than the others. But over all happy as.

Def know now it puts the ssts out nicely so abit more accuracy on seating lengths and poweder weight should be mint eh! That 18ft per sec variance on 42.5 would likely be a few points gr over of powder eh? Plus as said before it's the only shot that didn't feel quite on.
Also seems like the 3rd shot of each group was abit wayward. Could be caused from Barrel temp issue with not cooling down enough between groups eh?

Originally Posted by bjp

Get good correlation in GRT (Gordons Reloading Tool) between your loads and measured velocities assuming a 2.80" COAL (GRT = 2645 fps). It shows hitting around 58k psi at 43.0g, and just over 60k psi at 43.5g. You might be able to get a little more speed, but it also might be at the expense of case life. Though at least brass is readily available for 308.

If you are happy enough with velocities, have you measured the max. COAL for your cartridge in this rifle? You could try adjusting jump to lands to see if things tighten up - though there appears to be no significant difference in the 42-43.5gn range. You would need to start shooting larger groups to do any real analysis. But it all looks good enough to hunt with!

Col was 2.750 but with the slight dif in tip size there cold have been slight .005-.010 differences. Hence a couple of tighter bolt closes.

Originally Posted by Randynz

Range was busy tonight was the last one through. Barrel didnt get hot but was def warm. Results are in. Could be some goodness between 42 and 42.5
Feel like the 3rd shot of 42.5 was maybe a . Higher with powder. But wasn't 100 on that shot too. Was the only one I didn't feel good about then checking down spotting scope seen how high it was confirmed that.
Will make some more tests up between 42- 43 at .2 increments and see if I can sweet spot it. But overall happy with the ssts!!! Cheers for the input

Attachment 286132
Attachment 286133

Greetings @Randynz,
Our results demonstrate the differences in velocity due to differences in components. In your rifle 43 grains of AR2208 and the 165 grain SST produced 2,640 fps where the same charge in my rifle produced 2,575 fps with the 165 grain Interlock. Magic? Not really. My cases were CAC which are quite roomy where your Sako brass is likely to be heavier and with less capacity which pushes the pressure and velocity up. Additionally the SST projectile is much longer than the Interlock. When seated to the same LOA the whole of the SST boat tail projects past the position of the flat base of the IL. This pushes pressure and velocity up some more. Finally my rifle was manufactured in 1975 and I am guessing yours was made much later. Tolerances have tightened over the years and velocities yes and pressure too have increased This is the reason we shouldn't use old data from the 60's.
Regards Grandpamac.

Originally Posted by Randynz

Range was busy tonight was the last one through. Barrel didnt get hot but was def warm. Results are in. Could be some goodness between 42 and 42.5
Feel like the 3rd shot of 42.5 was maybe a . Higher with powder. But wasn't 100 on that shot too. Was the only one I didn't feel good about then checking down spotting scope seen how high it was confirmed that.
Will make some more tests up between 42- 43 at .2 increments and see if I can sweet spot it. But overall happy with the ssts!!! Cheers for the input

Attachment 286132
Attachment 286133

0.9moa,,42gr.
Load 5 more to confirm.
If OK, job done.
Load 20 - 40 and just go hunting.
Tinker later at your leisure.

BTW, before youi spend a whole lot of time (and resources) chasing tighter groups with 3-shot samples, you might want to read this... or maybe not!

https://www.nzhuntingandshooting.co....8/index18.html

FWIW, my current approach is to get the velocity I'm after (within reasonable limits), and if its not spraying them all over, and the velocity SD is good, shoot a careful 6+ round group to find a zero (or near enough) then call it a day, go find some wildlife to fill the freezer.

Though I'm struggling with the last part at the moment, finding time to head into the hills is much harder then sneaking off to the range for an evening!

Originally Posted by bjp

BTW, before youi spend a whole lot of time (and resources) chasing tighter groups with 3-shot samples, you might want to read this... or maybe not!

https://www.nzhuntingandshooting.co....8/index18.html

FWIW, my current approach is to get the velocity I'm after (within reasonable limits), and if its not spraying them all over, and the velocity SD is good, shoot a careful 6+ round group to find a zero (or near enough) then call it a day, go find some wildlife to fill the freezer.

Though I'm struggling with the last part at the moment, finding time to head into the hills is much harder then sneaking off to the range for an evening!

there's this one which may be helpful


https://www.nzhuntingandshooting.co....opment-106057/

Load up another 10 at 43.5 gns and shoot another group. Horizontal dispersion is often more shooter than load. Not much difference in any of those groups to make you use less than 43.5gns.


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Originally Posted by Randynz

Range was busy tonight was the last one through. Barrel didnt get hot but was def warm. Results are in. Could be some goodness between 42 and 42.5
Feel like the 3rd shot of 42.5 was maybe a . Higher with powder. But wasn't 100 on that shot too. Was the only one I didn't feel good about then checking down spotting scope seen how high it was confirmed that.
Will make some more tests up between 42- 43 at .2 increments and see if I can sweet spot it. But overall happy with the ssts!!! Cheers for the input

Attachment 286132
Attachment 286133

Did you make scope adjustments between groups?

I think working up in .2 increments between 42 and 43.5 is a waste of time and components. Shoot more rounds at 43, 43.5 and 44.


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Originally Posted by gimp

Did you make scope adjustments between groups?

Nah just shot at the target below the one it was hitting at. I re zeroed for 200 with the velocity check for the 150 factories I have. Incase I get a walk in before finishing development

Originally Posted by Dicko

I think working up in .2 increments between 42 and 43.5 is a waste of time and components. Shoot more rounds at 43, 43.5 and 44.


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Keen to get up to the high 43s/44.
Max load data showing 43.7. But yeh no pressures signs at 43.5. Anyone know if the white river primers show signs early or if they are abit harder and only show late?

Originally Posted by Dicko

I think working up in .2 increments between 42 and 43.5 is a waste of time and components. Shoot more rounds at 43, 43.5 and 44.


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Barrel was pretty warm by the time i got to 43 and 43.5
Def need to see those shoot from cold eh. And have a bit of time. I'm away working next week or so. So won't be doing any more testing for a little while now.

Originally Posted by grandpamac

Greetings @Randynz,
Our results demonstrate the differences in velocity due to differences in components. In your rifle 43 grains of AR2208 and the 165 grain SST produced 2,640 fps where the same charge in my rifle produced 2,575 fps with the 165 grain Interlock. Magic? Not really. My cases were CAC which are quite roomy where your Sako brass is likely to be heavier and with less capacity which pushes the pressure and velocity up. Additionally the SST projectile is much longer than the Interlock. When seated to the same LOA the whole of the SST boat tail projects past the position of the flat base of the IL. This pushes pressure and velocity up some more. Finally my rifle was manufactured in 1975 and I am guessing yours was made much later. Tolerances have tightened over the years and velocities yes and pressure too have increased This is the reason we shouldn't use old data from the 60's.
Regards Grandpamac.

All good info in there eh! Iv gone the 2206h for the faster burn rate with the shorter barrel. Ruger m77 mk2 so prob late 90s. Love it. Light enough and drops deer. Hasn't had a load that shoots shit out of it too which is a bonus

Thanks @grandpamac

Originally Posted by gimp

there's this one which may be helpful


https://www.nzhuntingandshooting.co....opment-106057/

Good read bro cheers!!! Yeh 1st handloads and ssts id put through rifle. wanted to make sure they would group at all. Previously used sp's.
Do 10 at 43.5 and 10 at 42 or 42.5(make it 42.75 for shits n giggles) Pick the winner and go from there haha. Thatll leave me with 62 bits and bobs for animals for now haha

Originally Posted by Dicko

Load up another 10 at 43.5 gns and shoot another group. Horizontal dispersion is often more shooter than load. Not much difference in any of those groups to make you use less than 43.5gns.


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The 43.5 with 2 almosy touching and the 3rd slightly right is showing good signs eh
Especially with my limited shooting experience