257 Roberts AI Finally!

TG1911 said:
Starting with RL17 and 115-gr Ballistic Tip. I have many choices of bullets, so it should be a fun summer at the range. The local range should open in 6 weeks or so. When the snow melts. Currently I drive 2 hous each way to a range.
Click to expand...
Nice!
I am going to try Re-17 and the 115 gr BT in my 257 Roberts.
QuickLoad is suggesting that I should get up to 3085 fps out of my new-to-me custom LH Sako M591 with a Shilen 22" barrel, w/ a max load at 45.2 gr of Re-17.
A max load of 45.1 gr of H-414 should get up to 3041 fps.
Luckily, I have a decent supply of each powder, primers, and bullets in stock.
Will have to see how these perform!
 
Thanks. That’s a good start for me on working up loads. With a 24-inch barrel I might be pushing 3100fps. 🤞
 
TG1911 said:
Starting with RL17 and 115-gr Ballistic Tip. I have many choices of bullets, so it should be a fun summer at the range. The local range should open in 6 weeks or so. When the snow melts. Currently I drive 2 hous each way to a range.
Click to expand...
Blkram said:
Nice!
I am going to try Re-17 and the 115 gr BT in my 257 Roberts.
QuickLoad is suggesting that I should get up to 3085 fps out of my new-to-me custom LH Sako M591 with a Shilen 22" barrel, w/ a max load at 45.2 gr of Re-17.
A max load of 45.1 gr of H-414 should get up to 3041 fps.
Luckily, I have a decent supply of each powder, primers, and bullets in stock.
Will have to see how these perform!
Click to expand...
Be cautious with RL-17 when the temperature rises so does the pressure. I used it back in 2017 or 2016 in my GAP 260 for competitions and sadly was unable to keep it at the expected velocity when I developed it.

I had always used 42.5 H4350 behind a 139 Scenar. Why I thought the extra speed was a better idea is beyond me. I can probably say the same thing with the Norma URP I have too, very similar to RL-17 in burn rate.
 
I’m going to do more of a speed demon, 25/7PRC , but I had been planning on something a little milder, 25/284? Borden Timberline Mag action with a Watts extended box in a Hawken M5 BDL, that allows you to swap it out for a M5 DBM. It’s going into another MCS T Elite Tach Carbon stock so it should be a good bit lighter than what I normally use. It’ll be a 9-10 lb. hunting gun if my math is correct.

image.jpg
 
longrangehunter said:
Be cautious with RL-17 when the temperature rises so does the pressure. I used it back in 2017 or 2016 in my GAP 260 for competitions and sadly was unable to keep it at the expected velocity when I developed it.

I had always used 42.5 H4350 behind a 139 Scenar. Why I thought the extra speed was a better idea is beyond me. I can probably say the same thing with the Norma URP I have too, very similar to RL-17 in burn rate.
Click to expand...
I'll keep that in mind for antelope hunting, as it can be in the high 20's (approx 80 F) in Sept in Alberta.
For deer season here in November it is usually well below zero (32 F) so shouldn't be a problem.

While velocity is great, I load for accuracy, which usually nets less velocity. (of course, I am happy when I get both! 😁 )
 
longrangehunter said:
Be cautious with RL-17 when the temperature rises so does the pressure. I used it back in 2017 or 2016 in my GAP 260 for competitions and sadly was unable to keep it at the expected velocity when I developed it.

I had always used 42.5 H4350 behind a 139 Scenar. Why I thought the extra speed was a better idea is beyond me. I can probably say the same thing with the Norma URP I have too, very similar to RL-17 in burn rate.
Click to expand...
Interesting observation. I've been running RL17 in my 7x57 with the 150 gr. Nosler Partition and hit right at 2880 FS. Bolt lift was only very slightly sticky at that level and dropping to 2800 FPS showed no stickiness whatsoever. I do all my serious hunting load workups during the summer with temps running from 100 to 115 degrees. If pressure is going to show up fast it'd be at that time of year. I think the 2880 FPS load would work just fine during hunting season when it's a lot cooler. I wnt to use that7x57 on an elk hunt so will either go with that 150 gr. Nosler or the 160 gr. Speer Hot Core. I think I can easily reach 2600 FPS with that bullet.
It's not that my loads are all that hot for the cartridge but the rifle is a Winchester M70 Featherweight and I'm using 7-08 data for my reloads. The 7x57 Mauser case can hold up to three more grains of powder than the 7-08 so sticking with published 7-08 data should be just fine. FWIW, that Nosler load runs right at .55" on average for accuracy. Good speed and great accuracy, what's not to like?
Paul B.
 
PJGunner said:
Interesting observation. I've been running RL17 in my 7x57 with the 150 gr. Nosler Partition and hit right at 2880 FS. Bolt lift was only very slightly sticky at that level and dropping to 2800 FPS showed no stickiness whatsoever. I do all my serious hunting load workups during the summer with temps running from 100 to 115 degrees. If pressure is going to show up fast it'd be at that time of year. I think the 2880 FPS load would work just fine during hunting season when it's a lot cooler. I wnt to use that7x57 on an elk hunt so will either go with that 150 gr. Nosler or the 160 gr. Speer Hot Core. I think I can easily reach 2600 FPS with that bullet.
It's not that my loads are all that hot for the cartridge but the rifle is a Winchester M70 Featherweight and I'm using 7-08 data for my reloads. The 7x57 Mauser case can hold up to three more grains of powder than the 7-08 so sticking with published 7-08 data should be just fine. FWIW, that Nosler load runs right at .55" on average for accuracy. Good speed and great accuracy, what's not to like?
Paul B.
Click to expand...
Paul,

If you’re going to stick with RL-17 try to develop your loads in the same environment as you will hunt in. That way you’ll have a better understanding of what velocity you’re going to be seeing when hunting?

Back when I was using RL-17 as the sun came up it was usually on the chilly to cold side and as the day went on the temperature was rising throughout the day. Which was causing issues for me during a match. Back then it was a guessing game, but now there’s rifle mounted chronographs that are very good at tracking what your velocity is doing.

I don’t use them while I’m competing, but I have seen the issues that I’m speaking about in real time during a full day of shooting.

If you’re happy with what you’re getting, and not shooting at long distance, don’t worry about it. It’s usually when a load was developed during the winter, and then out shooting in hot weather that the real problem becomes an actual issue.

Nothing worse then being unable to open your bolt when you are out hunting and need a second shot. Soft brass can cause the same issue too! Even with a normal load.

If you’re wanting something that will perform in all weather conditions and temperature swings, try something that is not as sensitive to temperature fluctuations like the Extreme Hodgdon line, Vihtavuori, or something similar. Alliant powders are no longer being sold since Vista sold the company to the Kinetic Group as far as I know.

I was a Vista shareholder and unfortunately not only did they sell they off The most profitable portions of the company, and kept the lowest margin business of the company! A bunch of dumb asses!
 
Well that should give you a good place to start. Very nice. I’m betting, given you just threw those loads together, your rifle is going to shoot just about everything you dream up pretty well. I guess you’ll have to spend more time at the range once the snow melts and stretch her out some to see one load is clearly better than another. Tough way to spend a summer.
 
I finally got the new Brux seasoned, good enough to start experimenting and working on a load withthe 88 grain bibs HPBT. My bullet of choice I built this rifle around for varmints on out there. I also have a supply of 85 grain Balistic tips, I will try when I get a load developed with the Bibs, and that might be sooner than later!

Pretty miserable day at the range yesterday rain and mist, fog in and out, windy to gusty, you know, a perfect day for seeing real conditions and how a hunting load will prevail,,,, (y)

Anyway I only took 2 loads for the 257 which is now showing signs it is broke in and ready to give some honest results. I shot one load with the=ree shots while breaking in using the ackley formed cases, but now have 42 cases made and the breakin is pretty much done. So I'll run these two loads with H4350, one with 53.5 grains of H4350, and one with 54.5 grains and Federal 215 primers. Loaded .005 to .008 into the lands. I also wanted to spend the hole day so I'll clean and finish fire forming the other 8 cases i have yet to form in the 8X57 Mauser brass I used for this build from Lapua. EXCELLENT brass and very tough!

The first group on the lower bull was 53.5 grains and showed promise, but the H54.5 grain load might just be THE load? One shot out or I would be done on the first round, but that one shot on that top target could be anything, seating depth, the case, or even a condition, since the weather was so nasty and no flags set out in this rainy weather. Hell at times I could use the rain for windicator, but mostly was doing my testing in let ups and very light drizzle. It shure made for some soggy targets, in true hunting conditions. Even though they were just 100 yards.
20250521_171803[1].jpg

Both 5 shot groups, and the H4350 is a powder I have good luck in another 257 AI with medium weight bullets. Some one even suggested that the one out with the 54.5 grain load could have been me,,,:rolleyes:

This is definitely close if it aint the load, and 3719 fps average it shows why I chose the Bob. In my opinion it is the perfect 1/4 bore round. It might not give quite as much velocity as some of the inefficient larger ones in 25 caliber, but nothing meets the efficiency, of this cartridge. Ya you can burn 20 to30 more grains to weazel another 200 or so fps, but forget 1/4" groups, forget any reasonable barrel life, and get some good ear plugs. I will build another on the 700 Remington lonag action I just put together in a sporter for 110 accubonds and deer and antelope. I also wish I had the ability to put that 257 on a sheep hunt, in my opinion again, as good as it gets for these tasks!

I have always been impressed how such an old cartridge can perform at the level the Roberts does, and been kicked aside for so many decades, nearly a century. It is a classic I won't be without, and the Ackley version makes it a true long range option for medium big game, as well as long range for varmints. this rifle will be getting bled very soon. In fact I think it might just be ready now? The next range session should verify that one way or the other! Anyways she is zeroed and the zero locked on the fine Sightron LRP SIII IL 8-32x56 MOA-2 scope, It was a perfect match for this varmint rig, on the range the 10-50 version might have been better, but for field use I rarely am able to use 32x, and even at that power, the scope is bright and clear, with a great reticle. Not bad for ancient cartridge on a Cheap Savage action,,,, ;)
20250122_172231[1].jpg
 
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