I'm in the load development stage for a new 280 Ackley. It is a Cooper Excalibur, 1:10 twist. Looooong throat. Magazine length 3.400".
I have some questions related to powders for this rifle but first here is what my load data consists of:
Nosler custom 280 ackley brass(neck sizing)
Nosler 160gr Accubond bullets
COL = 3.330”
Powder H4831SC and RL22
I did barrel break in with some less expensive hornady interbond bullets and had some 1/2 MOA groups so I was excited to progress and improve from there. That seems like a long time ago and I'm not satisfied, well partially.
I started loads way down at 55 grains and worked clear up to 63.5 grains with only a couple slightly sticky extractions. No primer cratering or flattening. I still am a tad nervous about that upper load being too hot even though I shot them between 75 – 82 degrees f.
I started with the H4831SC because of the temperature resistance. I’ve read about the freeze tests etc and those test would mimic my range of environmental conditions. My elevation use also ranges from 1000ft to 8000ft. This is my do it all rifle, though I have several others, so I would prefer not to add powder as a cause for POI changes on top of the already extreme environmental conditions.
So the H4831SC had fair results with a few groups in the .75”-1moa but when I switched to the RL22 those groups where cut in half and across a wide powder deviation. I shot a string of 3 round loads starting at 58.5 in ½ grain increments up to 61.5. of those 6 – 3 rnd groups one was .26”, one was .35”, one .46”, one .80 and the other two larger. I was extremely impressed with the rifle but not happy about the Hodgen powder not working out in this rifle.
Maybe I’m getting to critical over these details but I’m planning to have dials made by leupold and I’d like them to be as close as possible for the loaded ammunition as possible.
I still have not worked on bullet seating to fine tune the loads.
Any advice on getting the H4831SC to work?
Is it reasonable to expect to be able to get the H4831SC to perform to what I’ve already seen from the RL22?
Would you recommend another temperature resistant powder like H450(is it even available?) or H1000, others?
It’s damn near hunting season now so I’ll be loading the RL22 powder but will be back at it after the deer hunt and before the elk season which is at the end of October at 8000ft.
For what it's worth, I went through the same thing with my Rem 280 Ack. I tried just about everything under the sun and by far the most consistent powder was the 4831sc. My rifle for sum reason just would not group the accubonds so I finally gave up on them. They would group in around .75 to an even inch but I knew both myself and gun were capable of more. I finally gave 150gr Barnes TTSX's a try and they consistently grouped at or under .5". Then I used Hornady Amax's and would get the groups the accubonds were shooting at 300 yds. The point of impact for the ttsx's is so close to the amax's at 300, I just shoot those at critters to that distance just to be safe, (I did shoot a deer last year at 180 with the amax and it did just fine though).
I believe my load turned out to be 59gr for the amax and 60.5 for the barnes. I'm sure I could go substantially higher but the accuracy is there so I stopped. I'm also using the nosler brass but with winchester primers. Hope this helped...........
I shoot the 280 Ackley Imp. quite a bit and I have found that Retumbo works very well in your bullet weight range. I use 63.0 grains of Retumbo with a 168 grain Hunting VLD from Berger and have taken game with this also with excellent results. This load gives me right around 3050 fps out of a 26" Pac Nor Super match grade barrel with 3 grooves and a 1:9" twist. One item that is over looked is that when you have a charge of more than 60 grains you may need a magnum primer depending on what powder you choose to use.
I hope this helps you with your loads.
Wouldn't it be great if we could pick the powder/bullet combination we wanted and it just worked , unfortunatly its not always the case.As above you could try a primer switch.
In the same rifle as yours I found N165 with the A max and N560 with the 140 TTSX the best.168 vlds also very good with N165. 160 acubonds gave me no consistancy at all.
Im not to concerned with the temp change as I carry the Barns in the Mag( they fit where the A max are to long) and a few amax rounds in a wallet in my pocket and keep them close to body temp for the longer shots.
Thanks a bunch to all three of you with reply's. I thought I'd get a wide variety of more general comments and advice that I would have to weed out any good info from and all your comments where good ones and what I was looking for. Much appreciated. I do have a box of mag primers to try and I will probably try both retumbo and the n165 powder. Looks like retumbo is quite a bit slower than what I'm using so I'll do some more reading on that one and maybe use a mag primer on that too.