280 AI Results with 175-180g bullets

[osok-1k]

I'm working on a 280 AI build, trying the Ace Sendero profile 1-8 twist and 26". I would like to use Grand powder, Nosler brass and Federal 210 primers. Hornady 162 ELDM will be my starting bullet. I'm not a speed hog and like to keep things around 3k or less. Anyone using Grand?

 

[lancetkenyon]

Here's some rather conservative data provided by Berger for their bullets.
View attachment 621371

I wouldn't say the RL23 info is conservative for charge weight, but is for speed. I have loaded for a lot of .280AIs.
With a 175 Elite and Nosler brass, I find 58.7 to be about max, but speeds are far greater that 2800. 26"=2950+, 24"=2900+, 22"=2840+.
With Peterson brass, drop max charge weight by about .5gr. 58.2 is about max, and speeds about 10fps slower than above. But much better brass.

 

[VinceMule]

I formed some brass for one rifle out of Lapua '06 brass, skim neck turned to clean up the high side.
This brass is unreal tough, I don't think you can kill it.

 

[7mmAI]

Tried some retumbo loads at 62.0 gr with 2 diff seating depths one 10 thou and one 30 thou off the lands. 3.440 is my coal for this load for 10 thous off. Both shot very well and same point of impact and velocity 2950 fps ish. Tried 62.5 gr again and just like last time poorer accuracy and no increase in velocity.
57 gr of reloader 23 at 10 thous off lands was 2960 fps and extractor swipe and hard bolt lift so that experiment is over. Not that it might not be accurate with less powder and less velocity but retumbo is so good...
My other trial was v560 at 61 gr at 10 thous off velocity of the 2 i shot was 3006 and 3066? I question the 3066 but my labradar has been very consistent so i believe it. The group was not good and wild spread I saved the other 3 to pull.

Guess only thing of real interest to me was the confirmation that 62.5gr or retumbo gives no more velocity than 62 gr and poorer accuracy.

So this might be my shortest load development ever ladder to low 60's gr of retumbo on my first load day showed real promise and that will be it!

 

[Raudy707]

Norma Brass
58.3 grains of Rldr 23
Fed Gold Medal Match 210 primers
2980 fps
26" barrel
0.338 MOA @ 100

 

[letrbuck]

57gr of staball 6.5 got me over 2900fps in peterson brass with 175gr partitons. I settled on 56 grains which is .2gr above book max and still get ~2880 fps

I should try the 175 eldx or 190 eldm, but recently acquired 1800 162 amax that will be keeping my 280 ai fed for a while...

 

[7mmAI]

Letrbuck, If you are getting that much out of the 175 partition with as much bearing surface as it has i would guess you could get more powder and velocity out of a berger or eldx in the 175 gr weight. It has been my observation that bearing surface is as big of a factor in finding pressure as is bullet weight. If I wasnt having so much luck with my retumbo load I might have to give that staball 6.5 a go.

 

[letrbuck]

Letrbuck, If you are getting that much out of the 175 partition with as much bearing surface as it has i would guess you could get more powder and velocity out of a berger or eldx in the 175 gr weight. It has been my observation that bearing surface is as big of a factor in finding pressure as is bullet weight. If I wasnt having so much luck with my retumbo load I might have to give that staball 6.5 a go.

I was pretty surprised at the speed. I did a quick Ladder to find pressure using SB 6.5, RL26, IMR 7828, and h4831. I expected rl26 or 7828 to be the fastest, but the 6.5 edged them both out