280 AI load

[brokfut]

Loaded up some fire formed 280 AI with Barnes TTSX 140 gr and got this group. Started with 53 gr IMR4350 and went up to max of 56.7 gr listed in Barnes data. 53.5 gr was the sweet spot but no pressure signed at max. Everything above 53.5 opened up 1.80 to 2.25. Estimate this load at about 3000 fps but that's all it is is estimate. Drew a tag for Eastern Oregon in the high desert for mule deer and this will be my load for the hunt.

 

[N2TRKYS]

If you are happy with it, then use it. Personally, I wouldn’t be happy being that far from a max load. Also, I would verify velocity with a chronograph.

 

[brokfut]

N2TRKYS,
Please explain why a load has to be a max charge. I don't understand the reasoning.

 

[N2TRKYS]

N2TRKYS,
Please explain why a load has to be a max charge. I don't understand the reasoning.

I want all the velocity I can get. 3 grains is alot. Some will come on here and say, I’ll take accuracy over velocity. I haven’t found it difficult to get both with any of the rifles that I load for.

Again, if you’re satisfied with it, then chrono it and hunt it.

 

[ImBillT]

By no means do you have to use a max load, and sometimes the advantage of a larger cartridge is that you have more room for tuning without sacrificing some minimum level of performance. That said, considering I’m shooting a 180gr VLD at 2950fps from my 280AI, 2980fps with a 140 seems like you’re leaving a lot on the table.

Powder charge doesn’t usually take a .5” load to 2”.

How many times in a row did 53.5gr produce a .5” group?

 

[Wind Gypsy]

Powder charge doesn’t usually take a .5” load to 2”.

How many times in a row did 53.5gr produce a .5” group?

That was my first thought as well. If 53.5 shot 0.5" with a single 3 shot group and everything above that charge shot 1.8"+, I'd be pretty confident that one 3 shot group @ 53.5 is an outlier rather than the norm.

 

[Arcola]

That was my first thought as well. If 53.5 shot 0.5" with a single 3 shot group and everything above that charge shot 1.8"+, I'd be pretty confident that one 3 shot group @ 53.5 is an outlier rather than the norm.

This.

How are you “estimating” your velocity? I think your numbers are pretty optimistic for your powder choice/ charge/projectile weight.

I typically follow consistency between group size and sd, but 3 shots isn’t enough for solid data.

I burn a lot more powder (different powder) behind my 140 projectiles and find great accuracy just below pressure signs.

If your load turns out consistent over dozens of shots, run it. But find a way to measure velocity and make sure it’s sufficient for TTSX expansion at the ranges you intend on shooting.