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257 Roberts Ackley Improved

9K views 7 replies 6 participants last post by  jeepmann1 
#1 ·
i might be getting rid of my tc venture in 25-06, reloading dies, and 80 some pieces of rem brass. i'll be buying a encore in 257 Roberts Ackley Improved, 1 in 10" twist, in a 21" mgm barrel. i sent an email to mgm barrels to make sure it has a 40 degree shoulder, so that is taken care of. i have 2 full boxes of 115 grain nosler ballistic tips. do these work for deer, busting a shoulder, etc, or should something else work?
should fireforming be 87 or 100gr? would imr 4350 work? the ack imp is new to me, any help will be greatly appreciated...
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« Last Edit: Today at 07:14 PM by tdoyka »
 
#2 · (Edited)
tdoyka Welcome to the Quarter Inch Club and also an Encore owner. I have shot one or two fallow deer 150 to 180lbs body weight with the 115gr Noslers, but not to 'bust' the shoulder, because the meat there provides us with a lot of sausage and a lot of game pies through the winter. Popped just behind the shoulder, half way up the body, into both lungs and that deer ain't going far. The joy of doing that is , with the accuracy potential of that round you can choose which rib to hit, but best to slip it between the ribs and mush the interior. It also bleeds out the meat as well, as the heart continues to pump, so making the produce much tastier.
Although I am very much a Nosler fan, I have also had great success with the 117gr Hornady SST out of my 257 wildcat which is pretty close to what you will have in the Ackley version. Shot everything from 30lb muntjac, 50lb roebuck, fallow upto 200lb wild boar with that one and had no complaints from the receiving end :)
I have fireformed all of my wildcat cases with 100gr bullets and a mild load(48gr) of H4831, I then settled on 50.5grns as my working load because that gave me the best group with no pressure signs.
My cases are necked down from 7x57 (Norma)rimmed cases and then blown out. Put the bullet in the right place and a quarter incher will do a tidy job. ONE GOOD SHOT
If any doubts about the 117SST, I shot two roe bucks in Slovenia with one shot and the bullet passed through both at 150yrds, one buck was slightl back from the other but the bullet skidded off the shoulder blade of the first at a slight angle and hit the second perfectly through the lungs. A freak situation but just proved that SST will penetrate and do the job at the same time.
Apologies, didn't answer the important ?? Yes IMR 4350 should work OK and is listed as such. Will certainly be OK to blow the cases out and may prove to be accurate with the final loadings. I always load 5 cartridges and load a set of five, 1/2 grain apart, from the max shown in the handbooks, down, and then set up a large sheet of paper and put on five dots. I then shoot each group on the lowest power setting, ignoring the group and moving to the next, letting the barrel cool between each group. Then walk forward and see which load shot the tightest group.
I think you will enjoy your Encore. I don't have a big game bolt action in my tool box these days.
 

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#3 ·
Before anyone jumps in, I know you should ZERO on max power and do just that, but here we are seeing what groups best and not being able to see each group, you are not influenced by the fall of shot and just concentrate on the next group. Human nature means we can't help trying to adjust, which in this case we shouldn't, each group being shot like it was the first.
 
#5 ·
The proof of the pudding is always in the eating and I agree that some barrels just don't like certain bullet weights. My 257 one to ten barrel is quite happy with everything from 87grns up to 120 grains, shooting them all moa or tighter. The 117 SSTs perform best accuracy wise and if I haven't had a bad night or drunk too much coffee, it will make one ragged hole with five shots. My Ruger 257 Roberts did not like anything over 87 grs It was 1-14 and that is one reason for me choosing a faster twist for the wildcat.
My barrel is 16 1/2 inches by the way. As we all know , every barrel sings it's own song, even from the same maker, you just need to find the song sheet it enjoys best and that is part of the fun of buying a new rifle.
 
#6 ·
The only .257 Roberts Improved I had was my first one; a rechambered Mod 700 Classic. I fireformed my brass with Remington factory loads (100gr) and since this rifle had a long throat, I used the old Hornady 120 HP seated way out over a case full of IMR 4350/std primer. It was a gee whiz killer on SE Texas whitetail and crows...al it was ever used on. I think you will find those 115 BT to be just right for what you want. Good luck, and keep hunting!
 
#7 ·
The 21" bbl will limit your FPS with slower powders like 4350 and 4831. Best performance for the heavier 115, 117 & 120 grs will be with slower powders. But with lighter bullets, 87 & 100 g and quicker burn powders it will be a great, light weight combination.

A few years ago I rebarreled my favorite Mauser 98 with a 24" in 257 AI 40deg version. Being a wildcatter and dedicated PO Ackley fan, i enjoy the loading and testing. I began by fireforming factory 257 Roberts and necksizing afterwards. I settled on a 100 gr Hornady on top of 4350 at about 3300 fps for antelope, Texas whitetail, coyotes and other critters. Good accuracy, 1/2" three shots consistently but max pressure. Case life was 3 reloads at the neck. Annealing should help this. Great terminal results on everything hit. Next I loaded 120 gr Nosler at 3100 fps for mule deer, 400 yds shoulder shot proved to be max distance on the larger game, but still a one shot kill. Overall I like the 257 AI combination, especially with the 100 gr loads. Approach max loads with caution, chambers, bores, bullets will all behave differently in different rifles. Never had feed problems with the sharp shoulder in the Mauser. ... good luck and happy wildcatting :)
 
#8 ·
I have a 257 ACKI that is so accurate it is scary! it loves 4350 powder also. When fireforming Mr Ackleys pets (all Calibers) he advised a "stiff" charge of powder to properly form the cases.
I have found he knows what he is talking about:)Mine is deadly on p dogs with 90 gr Sierra HP bullets, it also shoots the 120 very well also.
Have fun with yours it is a great cartridge
 
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