I put 100 rounds of new Lapua brass through this Krieger 4 groove barrel this week with 41.8g 4064 and 175smk. At 50rd, I cleaned the barrel by putting some wet patches of Boretech C4 Carbon Scrubber, 4 strokes with a wet bronze brush then another wet patch, then I dry patched it out.
Today I dry tumbled the brass, sprayed the brass in a bin with my Lanolin/99% alcohol mixture and let sit 15min. I then used a Mighty Armory universal decapping die and Mighty Armory FL 308 sizing die, in a dedicated brass prep toolhead on my Dillon 550c set to bump the shoulders back .002". I then dry tumbled them again for 1hr to remove the lube.
After tumbling, I trimmed all the brass to 2.005" and chamfer/deburred the case mouths. Loaded all the brass up using my 21st Century click adjustable hand primer with CCI 450s.
Loaded up 10rd of IMR 4064 41.8gr with a 175smk for foulers. I then loaded up 3rd each from 41.6 - 42.4 in 0.2gr increments for the 175 SMK. They were all loaded on my Dillon 550c using a Whidden Floating die toolhead, Uniqutek clamp kit, Area419 Funnel with 1 drop tube and Dillon adapter on the powder die. Powder was measured on an A&D Fx120i with latest AutoThrow and AutoTrickler.
I then seated all 175smk to .02" off the lands with a Forster Ultra Micrometer seating die.
I loaded a second OCW using the same setup/toolhead, same powder, brass and primers, but used 175 TMK's this time. I loaded 5rd for foulers with 41.6gr IMR4064. I then loaded 3rd each from 41.4 - 42.2gr in 0.2gr increments. You will notice, I went .2gr lower than the 175smk. I did this because the TMK's are much longer and take up more case capacity being down farther in the case. Didnt want to use compressed loads
The 175 TMK's are MUCH MUCH longer than the 175 SMK. For reference, the 175 SMK touch the lands in this 308 Bisley chamber at 2.80 and the 175 TMK touches the lands at 2.93" COAL. So you can really see how much longer these TMK's are than the SMK's. I also loaded the 175 TMK OCW at .02" off the lands so 2.91" COAL. Im running ARC mags so I have plenty of room in the mag for these rounds.
This entire test was shot prone with MDT Cyke bipod and rear bag at 100yd. Temp 75F, Humidity 48%. Wind was 0-5mph
I DID shoot everything over the Labradar like always. Unfortunetly when I left the range I put the SD card in my pocket and had to make a few stops before heading home. Somewhere, I lost the thing pulling keys, wallet, etc out of my pocket. Not happy about it but is what it is at this point. This test is for accuracy so we have that info here.
First up, I shot the 10rd of 175smk foulers at the bottom of the target in 2 groups. Group on the left was the first and the high shot I still had my turret set for 200yd so thats why that first shot out of the rifle went so high. After shooting the 10 foulers, I shot the top row OCW charges from left to right in round robin style letting the barrel cool between strings.
Look at the POI's, I would say the node is 41.8 to 42.2 and I would choose 42gr as my load, regardless of if being the smallest group. Ill do a seating depth test with that next but its already showing good accuracy.
I let the gun cool down completely before moving on to the 175 TMK OCW. Once cooled down 100% I shot the 5 foulers at the bottom of the target. Heck of a 5 shot group.
I then shot the top row from left to right, round robin style, letting the barrel cool between strings just like the first OCW. Looking at POI, it looks to be a pretty wide node from 41.4gr - 42.0gr but really it looks pretty darn forgving across all the charge weights. No real major POI shift form any of the charges. Id probably go 41.7gr. I will do a seating depth with this one as well but as consistent as it was across all the charge weights Im not sure we are going to see a drastic group size reduction...
I do remember the lower end nodes for these 175 TMK's were in the 2585 - 2600 and 42.0 was 2633 and 42.2 was 2628 (yes it dropped even though it was a higher charge). Observation was they were roughly 10-15fps slower for each charge then the 175 SMK's.
After seeing how well these combos shot, Im pretty set on these 2 combos for the test. I dont see any reason to mess with more powders and bullets seeing the accuracy we are seeing with these 2 tests.