I was finally able to finish the load testing in continuance from the work up with Varget I posted a few weeks back. The time before last I determined a node around 42.0 grains of Varget when I was loading three rounds in .5gr increments. I then loaded 5 shots each in increments of 41.8, 42.0, 42.2, and 42.4. There were promising results in all of the groups from 42.0-42.4.
I was able to load up 10 rounds each of charge weights from 42.0 to 42.4 (.2 increments) today to further test accuracy and velocity in the 178 ELD-X's. I shot two 5 shot groups with each charge weight and shot them in the order 42.0, 42.2, 42.4, 42.0, 42.2, 42.4.
Velocity was measured using a Labradar. For this ES and SD I will use the average from each 5 shots. I also have provided an overall FPS, ES and SD from each group of shots of the listed charge weights I've shot over the last few months to give a better idea.
Accuracy is measured edge to edge subtracting bullet diameter with a caliper.
I hadn't cleaned my Mcmillan in quite awhile and decided to on a whim, I believe that to partially be why all the groups opened up a tad, or I also could have just sucked on the day I shot these groups. Either way, all of the groups were a bit larger than what I would normally like, but an average of all of the data from start to finish should still leave me with enough solid data to come to a decision.
Brass: Prime (Norma) 2.008 +- .005 1x Fired
Primer: Federal Gold Medal Match 210M
Bullet: Hornady ELD-X 178 Grain
Powder: Varget
OAL: 2.858 +- .002
Rifle: McMillan Tac-308 Schneider 11.00 Twist 26"
Scope: Bushnell DMRII 3.5-21x50
Temp: 83.7 F
Altitude 1312ft
Humidity 73.1 %
42.0 gr Varget 1st 5 shots
Average FPS 2646
SD 8.92
ES 21.72
Group Size .612
42.0 gr Varget 2nd 5 shots
Average FPS 2643
SD 10.39
ES 26.98
Group Size .400 w/o flyer
.642 w/ flyer
42.2 gr Varget 1st 5 shots
Average FPS 2658
SD 13.45
ES 32.31
Group Size .982
42.2 gr Varget 2nd 5 shots
Average FPS 2658
SD 12.15
ES 30.59
Group Size .692
42.4 gr Varget 1st 5 shots
Average FPS 2671
SD 9.07
ES 22.27
Group Size 1.192
42.4 gr Varget 2nd 5 shots
Average FPS 2671
SD 7.95
ES 18.14
Group Size 1.042
Several things of emphasis to note. I believe the results from the Labradar to be fairly consistent being as average FPS, ES, and SD are all similar in regards to charge weight even though the two separate groups (of same charge weight) weren't shot consecutively.
Group size was also relatively similar between each group of same charge weight, meaning I was shooting fairly consistent. If you look at the photos, even the way the groups look bear some similarity. Not sure if thats just coincidence or what...
Now onto cumulative data:
42.0gr Varget (4 data sets)
Overall FPS: 2645
Overall SD: 7.41
Overall ES: 18.6
Overall Average Group Size: .409 w/o called flyers
Overall Impressions: Although I do have an extra data set in this charge weight due to the initial testing from 40.0-42.0, this was my most stable load in terms of lowest SD, ES, and group size overall. Although the other charge weights did turn out smaller groups, overall throughout the course of testing this was the most efficient overall.
42.2gr Varget (3 data sets, only 2 usable data sets due to Labradar not set up properly after storm)
Overall FPS: 2658
Overall SD: 11.34
Overall ES: 31
Overall Group Size: .837 w/o called flyers
Overall Impressions: Turned out two out of three respectable groups of .472 and .692. I wish I had usable data from the group that I shot right after it stormed. I think this charge weight definitely deserves to be shot more at a later time. Respectable SD, ES is a bit high but not outrageous.
42.4gr Varget (3 data sets)
Overall FPS: 2668
Overall SD: 11.63
Overall ES: 28.21
Overall Group Size: .817 w/o called flyers
Overall Impressions: Turned out a .217 group for the best overall without a called flyer, however the 2nd and 3rd group shot were each over an inch. SD and ES were also the highest overall, however without the 1st data set and only using the 2nd and 3rd they are quite low (under 10SD and 20ES respectively). However the groups shot with 2nd and 3rd data set are also the ones that shot over an inch. Primers are also starting to flatten a tad and I experienced an extremely minor stiff bolt in this charge weight.
SO CAN I CALL IT A DEFINITE YES FOR 42.0 BASED OFF OF MY OBSERVATIONS???
Not quite sure yet. I've got 500 rounds of 178 ELD-X and all the components to load it. I think if I were to do so I would have no regrets. I still feel that 42.2 should be tested a bit more. Maybe load up 20 rounds of 42.0 and 20 rounds of 42.2 and go from there. Or maybe just split the difference at 42.1 and call it a day? My luck is that 42.1 would shoot awful! What do you guys think I should do? I haven't even tackled the issue of OAL and know that adjusting that may change things dramatically. I guess basically I want a round that will shoot .5 or better, over 2600 FPS, high .BC, and that doesn't exhibit pressure signs. I guess I pretty much have that with 42.0. Yet I'm kind a perfectionist. Help me decide!
The thing with load testing is that there are so many variables. And as shooters we can't hope to eradicate or eliminate them all while testing. Which is why a large amount of data averaged out should be a good option to give reliable data. Unfortunately for me that large set of data cost a lot of money in materials as well as a lot of time. I really appreciate everyone that has looked at and commented on this post. Being fairly new at this means that I'm open to any and all advice in the future, as I plan on working up loads in the future for my Seekins SP10 16" .308 as well as a Seekins Havak in 6.5CM that I should be getting in the next few months. Being in LE, I may be off the grid at times but will try and post when I can.
Thanks Again,
M. Wright
