Thread: 22-250 Ackley Improved Load Development

Another quick range visit.

Don't have enough of the Z-Max to fireform all of the Lapua brass, so I loaded a few more with 50gr Nosler BT's using a max 22-250 load of Benchmark 8208 for a nice increase to 3775 fps. I tried them with the same 35.0gr of BM2 as well and whilst the speeds were within 10fps of the Z-Max's 3650, the groups were not. Seems the rifle might not like these bullets as much and more experimentation is required.



But the main reason for the visit, was to try out the 88gr ELD and AR2217 combo, now that I had some fireformed Lapua cases. I had tried to model this in GRT beforehand so that I wasn't flying completely blind...



... Looked promising. But GRT rarely matches perfectly with reality without some tuning, so to play it safe I made a workup starting from 41.0gr up to 45.0gr, with 4 rounds at the two charges where I guessed (hoped??) I'd find some success. This was done in 1 grain steps to confirm safety whilst also minimising round count and fast forwarding to where the speeds should start getting interesting. I also extended the overall length to 2.670" after measuring to find that my "jam length" is 2.688".



41.0gr clocked 3024 fps and 42.0gr clocked 3086 fps. Neither showed any pressure signs, so I was good to push on. The POI's of the warm up shots looked reasonably consistent too which was promising. I dialled up 1 MOA and got a split group at 44.0gr with it bouncing between two distinct POI's which told me this was a bad spot - despite a velocity of 3252 fps and an ES of 4!! 45.0gr looked like it might tighten up again, although with sample size of two I can't be certain - however I did start getting some hints of ejector swipe which says this is pretty much a max load. The chrono didn't manage to register either shot but it will have been just north of 3300 fps.



The clear winner though was in the middle at 43.0gr with velocities between 3160 and 3174 fps and a really nice little group.



I'm happy with this. A little less raw speed than I'd hoped for, but great accuracy and consistency, plus kinder to the barrel and brass given it's a fair bit lower pressure than N160 was.