Desert Tech 308 OCW & Jump analyses. Feedback would be much appreciated

[PJT]

trying to develop a load for my desert tech ,
16"Barrel,
1in 8 twist
100m pipe range, no environmental effecting bullet, just operator error. Especially group 1 and 3, fighting the bag/rifle. As an indication OCW groups for 44.2gn & 44.3 gn were both 1cm.
OCW appears to be 44.2 gn Vhit N140 pushing a 175gn SMK - working purely from group size comparison between 44.0 & 45.0 gn in 1gn increments. Chronograph was a range supplied Shotmarker system with which there have been issues'
Jump analyses carried out between 10thou and 55 thou off the lands in 5 thou increments, OCW was carried out with a jump of 35 thou. this was chosen to mimic Typical ammunition There appear to be a couple of "good" points but first time I have ever done this so unsure of wether to place greater importance on group size or vertical stringing. Believe that either a jump of 50 or 55 thou (Groups 4 or 5) may be the optimum.
The Group Nos. are the order that I shot them in. The bullet holes down at the bottom right are different barrel and calibre nothing to do with the jump test, (didn't have another target.
These are some of the best groups I've ever shot , just want to make sure I'm picking the correct Jump.

Appreciate in advance any guidance
Phil

 

[Jordanwickham]

If it were me I'd load at 20k. Or test 60-65k and see if that's throwing .2s also. But 20-30k gave the widest seating node. 55 is definitely a great group but without knowing higher and knowing lower goes to hell it's a dicey spot.

 

[PJT]

Thanks Jordan, just what I needed, I'd been focussing on the smallest group, not looking for a wide seating node. Obvious really but only if you know.
Will try the 60-65k as well.
Thanks again.

 

[Jordanwickham]

Yeah I mean it is a 308 so erosion is fairly negligible but I'd still want to be where I have a decent amount of play and it look like 20k has good groups and a long time to hangout without needing to move longer. If 60-65k is around that .2-.3 range you can look into that. You'll have a little bit of velocity change with the loss of case capacity but honestly 20k looks real nice. I don't know what your purpose is but outside of Benchrest .3 is excellent.

 

[PJT]

Although I've been shooting a while, it could be considered as plinking really. Not interested in, nor have the time for rigid Bisley style Target shooting. As I'm getting a bit more time, wanting to start pushing more towards longer ranges and maybe the PRS style competitions. So have a lot to learn. looks like i'm going to enjoy the challenge, but going to need quite a bit of help, so the forum will come in handy, if people have the patience. As will tuition, if the Training team come over to the uk for a visit. Going to start knocking up some rounds for the next range visit, this time in the open air, not the pipe range, could be fun!!! Thanks and will update what I find out.

 

[Jordanwickham]

.3 is more than sufficient for PRS. Just need to know how to read wind and get some DOPE and you'll be right in there

 

[PJT]

Thanks Jordan

 

[PJT]

Jordan,
Update on my attempts to develop a round for my rifle, SRS 308.
Have completed another test with 44.2gn Vhitavouri, with the Jump ranging from 10 thou out to 65 thou. Shooting three round groups, which maybe should have been 5 round to allow for the odd flyer to be more obvious. However, fired thirteen sets, four obvious flyers identified by myself before round hit the target. Started the sequence of shots at 45 thou up to 65, then 40 thou down to 10. What was really interesting was that the first 45 group (fired groups of 45 thou) was totally different from the second 45 thou group. Think I must have been asleep when firing the first group. However, the results appear to confirm a definite sweet spot at 15 & 20 thou with ES & Sd below 4fps, other sweet spots at 35 & 45 with Es & Sd's below 8 & 4 resp". Groups for all jump steps were reasonable, but the sweet spot groups were the best of the lot. The main differences were the ES's & SD's were higher than the sweets spots. The range 50 thou to 65 thou, the es's & SD'd were consistent 16fps & 8fps.
Sorry cannot load Photo of target too large!

 

[PJT]

Photo of Target will not load, the spreadsheet and graphs are a poor substitute, But!!