This thought just occurred to me. You might also try a different bullet like the 162 eldx. I’m running it in a 7 RSAUM which is the ballistic twin of the 280ai, with h4350 with excellent results.
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Ok, so I’m sure this is a dumb question. What does the headspace indicate in this scenario? I get measuring it to bump it back 2 thous, but I’m not understanding in this scenario.
Below are my measurements
- Headspace (assuming I understand what you are asking) - 2.1375 (bushing 365)
- Max COAL - 3.373
- Max Ogive - 2.720
Initial loads shot
- COAL 3.280
- Ogive 2.625
I’m guessing .09 is likely too much jump?
What powder and grains did you use in your load?
I’ve been loading/hunting with the 280AI for over forty years, in fact I still have the original reamer for the first of a handful of 280AI’s I’ve owner over the years. All were accurate and generally pretty easy to load for. I started out with Partitions but switched later to the original Barnes X, then later to 145 gr Barnes LRX. Barnes are, by far, favorite big game bullet in everything from 25 Gibbs thru 300RUM and the 375’s put a serious hurt on buffalo. I played with loads a lot but had good success with 58 grains ± of IMR4350. Obviously seating depth is important but I agree with a previous poster - if a particular combination doesn’t work pretty well initially I don’t tinker with it; I save that for fine tuning around a bullet/powder/velocity I like.
Currently have a Cooper 280AI that shoots 1/2 MOA way out there with 58 grains RL22 and 168 VLDH’s but I haven’t shot anything with it other than steel and a hog.
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