New 280 Ackley Build

[Jokostel]

Just want to bounce an idea off of folks....
Right now that new 280 AI build of mine seems to eat several things VERY well..
my standard 140 load does well, however; I built this weapon for 168s and above.
Its got a #5 Brux finished @ 26 in + a vias break... and velocities seem to be SPOT on.
It seems to be pushing 140s right around 3200 with RL17... and with the 175 ABLR and 60 gr of I7977 it does ~ 2780. These are both running WLRM primers... OAL is 3.330

I was contemplating testing RL33 to gain some advantage thanks to the barrel length.
The question is... with the burn rate of that propellant, would I even reach pressure... say at 62-64 grains on a 175ABLR -180 VLD ? My "off-the-cuff" guess was to start at 60 and work up to around 64-65 grains.
Does quickload have ANY predictions for this, or am I looking at a waste of time even attempting this?

 

[eshorebwhntr]

I certainly don't think you would be hurting anything by trying. By all means be safe.

From what limited knowledge I have I wouldn't expect any huge gains over what you've already tested. To me, there seems to be an optimum point where cartridge case design and overbore, coupled with powder burn rate...optimize. If you were shooting a big overbore cartridge I would say you might gain something but being the 280 AI isn't largely overbore I would think there might not be much velocity left to be had over the 7977. But that's just me thinking, I have nothing concrete to back it up.

At some point going slower in burn rate is going to start having a negative effect on velocity. I guess the only way to find out for sure is to see which side of that "point" R33 is on for the 280 AI.

If you decide to try it let us know how you make out.

 

[PGJPJ]

I can't really be of too much help, but someone ran QL for the 280ai and 168 ABLR. I don't know what it's called, but there is a chart that will list out the top 30 or so powders in terms of max achievable velocity in QuickLoad.

Anyway, RL33 for that bullet was about 10 down the list. RL25 was at the top, 7828, RL22 MRP, etc were also all above RL33 in max speed.

 

[MudRunner2005]

I agree with the above post. RL33 seems like it would be a bit too slow for the moderate case capacity of the .280 AI.

RL25 and 7828 SSC are very close in burn rate. I use 7828 SSC with good results in my .25-06 AI and .30-06 AI. The .280 AI is right in the middle, so I wouldn't see why it would be any different.

 

[Jokostel]

That's what I was kinda figuring...
I was looking at RL25/7977 they all seem to top out at about 95% of the case capacity... the only reason I was entertaining RL33 is the fact of how dense it is. I could just shut up a and be happy with 7977....
I did find a REALLY odd node when I had my 300 Win Mags... 84 Grains of Retumbo and either a 180 or a 200 grainer (top for a 200 grain) Oddly enough I was getting good accuracy with 180 SSTs @ 3250 and 200 Speer Hotcores at 3150. Brass life was **** good as well.
gun)

 

[MudRunner2005]

A few months back my local store got some 7977 in stock (finally)... and I bought some. Loaded up some ladder test loads for the STW, but haven't gotten to the range yet. It's supposed to be extremely temp-stable.

 

[B-P-UU]

I would try RL-26 first.. Velocity with 26 has been unreal in some cartridges.

 

[Hornhunter32]

I would try RL-26 first.. Velocity with 26 has been unreal in some cartridges.

Then try Retumbo if RL-26 doesn't work.