.22 ARC 88gr ELDM VV-N550 Boltgun load data

[PGW Steve]

I made a post last fall of my first experience with the .22 ARC with load data and 80gr SMK's here -> https://forum.accurateshooter.com/threads/22-arc-cz527-re-barrel-adventure.4162889/#post-39306081

Running numbers for the 80's vs 88/90's shows a clear advantage for the heavier bullets. They gain about 100 yards of supersonic flight, and that is something that interests me.

We had some warm weather, around freezing, and oddly enough, no crazy south wind. I managed to get my hands on 300 of the Alpha .22 ARC cases, and I'd previously acquired some 88gr ELDM. I had a box of 500 90SMK's inbound, but they didn't show up in time for this warm spell.

My plan this time was to do 100% of the load test at 365 yards in my yard on the Shotmarker.

I had to snow blow my bench. The top has a cover that is on a hinge so when I flip it off, it makes a table on the side, and I don't have ice on the bench top.


The next issue was not feeling like walking out to the target to set up the sensors, and the SXS was in storage for the winter. There are three rows of tires, staggered and filled with sand.


The bench is the 50 yard bench, and doubles for the 365 target. I need to modify the pads so it can be swiveled for the far target, it's a bit awkward.


The Davis weather station is just to the right of the backstop, and about 20 yards behind.


I'm shooting SE, so it was a wind from about 7 o'clock.


I was using the new Garmin Xero C2, I really like the ability to control it with my phone. When I shoot out of my shack as seen in the previous post on the 80's, it makes it a LOT easier.


Limited to six pics, so this is part 1

 

[PGW Steve]

I used a Hornady gauge to find the lands, and picked .020" off the lands. I started with 27gr of VV N550, and went up .3 gr at a time, single shots. I only look for pressure, and velocity. I do not subscribe to the methodology of velocity 'nodes'. Charges and speeds on the target.


Once I get to a pressure speed combo I'm happy with, I load 5 and see what I get for a group. I increased another .3, so 30 grains now, at the seating depth I ran the ladder with, I had a group of 2.5" IIRC, which didn't impress. Normally I'll make a bold move of -.02" and then +.02 to explore more jump, or on the lands. I started with another .02" of jump, so .04" or so for the next five. As you can see, it responded well to more jump, and 4 of the 5 being under 3/4", I left it at that.


Five shots, with 30 gr of N550 and an 88 gr ELDM jumped .04" gave some great numbers on the chronograph.


The whole load development took 20 rounds, I loaded the remainder of the 88 ELDM's and await some nicer weather to stretch it out. At this speed, I'll be above the 1250 fps threshold for the Shotmarker sensors at 1200 yards.

I also have a great baseline for the 90 grain Sierra Match Kings.