Loads for 77gr TMK

[markymark]

So was back at the range, decided to develop the 24gr load and try a 24.3gr which wasn't part of the same testing last time. I tested each load at 4 different COAL's. I pretty much achieved a rough average of 2,668fps. The .3 extra grains didn't seem to alter the MV at all. Here are some of the results below:

 

 

 

 

Across both load outs the COAL of 2.283" seems to consistently prove to have the best results but as you can see nothing really shoots bad. I did start getting some pressure signs on the longest COAL which was the same as the longest I tested last time. Which I think proves that you guys were spot on about it being jammed in the lands causing the pressure to rise.

 

All in all a happy man with the results and the MV as it stands should keep things fine as go into the summer months, but will keep an eye on it when it warms up. Now on to make a large batch and to start enjoying. A trip to Orion in the not too distant future.

 

Thank you to all who contributed to this thread and help me along with my load. Certainly more wise to reloading. .308 / .357 reloading to start shortly!

 

Cheers again,

 

Mark

[VarmLR]

Was your vertically spread group on the lower picture (above, top left) shot rapidly Mark, with a hot barrel by any chance? It, and the group to the right of it seem to have a nice low horizontal spread. I'd be running with one of those two loads and concentrating on consistency and accuracy when doing the brass prep and charging. The vertical spread might be caused by high ES rather than a barrel heating up (were all groups run through the chrony?), and if tighter could be your best group there. Just a thought.

[markymark]

For all the groups i allowed the barrel to cool down and waited a good time between each shots. It could be caused by ES but that said I tried my hardest on everyone to get each charge weight right on the money. All loads were chronoed afterwards with additional rounds rather than on the rifle at the time. I have a magnetospeed so didn't want the bayonet to disturb the barrel harmonics and grouping for the test.

 

Some rounds were achieving an SD of 1.4 another's all the way to 18. But also did a load of 23gr straight with the volume charger for fouling shots and messing around with a sloppy SD but still managed cracking groups. There is obviously other stuff in play here, but I have very limited / cheap reloading equipment to which I'll invest in a proper set up in due course.

 

My .223 rifle doesn't really get on with factory loads, unlike the .308. Around 0.5MOA I'm happy with for the equipment I've got. Just happy with the money savings. Will have to see how they perform at exstended range.

[gbal]

Marky "there is obviously other stuff in play here...' indeed there will be.....once MV is down to about 15 fps or less,the contribution of powder to variation is rather small at short range....(you may well be there-I am not sure what the first sentence in your para two means,but it hardly matters.) Two other ball park equal factors are bullet seating tension variation,and perhaps case capacity variation/pressure.

You mention throwing by volume.....this is standard practice for 100/200y Bench Rest shooters,and they seem to shoot rather small groups (5x5 shot aggregate much over .25 won't win much ).

The other issues are : does very small group size actually matter?

And,is much increased expenditure justifiable? For some,yes-then the issue is what should be the priorities.

.1g is about 4 kernels,maybe 5fps. A good tuned beam scale will halve that,and is just nicer to use for £100 more,approx-but you may not see it on 100y targets-remember the BR guys,and they really do have serious precision rigs. Often as not,premium bullets will show more returns (Bergers eg don't need much more per box ,esp in 224-worth a try). Bryan Litz seems to agree-make informed decisions about priorities via his miss reduction analyses. See also Precision Rifle Blog "What matters" for the same general advice. Enjoy-if it's a hobby;consistent skill remains the largest factor in most contexts-unless the playing field is very uneven. :-)

gbal