257 Roberts max loads question

[SuperCub]

I am starting to work up loads for 100gr bullets for my 257R. Tried three different bullets today. Most manuals call for about 47 or 48 IMR4831 MAX!!. I got to 49 today with NO pressure signs at all. I had none loaded for more.

Primers rounded. Easy bolt lift on all three bullet brands. Primers were CCI Mag primers. Bullets seated .020 off the lands.

Is 50 or 51gr IMR4831 unreasonable??

 

[hs4570]

257 Roberts

I'll leave all the usual " exceeding max reloading data '' warnings to those that actually load and shoot for this cartridge . I can advise that the Lyman # 42 printed 1960 is the only load data that lists 49.0 gr Imr 4831 with a 100 gr bullet and at 3190 fps............all other manuals I own max out at less, 47 and 48 grains respectively being the highest quoted..

hs4570..................your mileage may vary

 

[RickF]

Paul, assuming at least a 22" barrel, loading the Roberts to modern pressures will get at or almost 3200 fps with a 100 grainer. Use the chrony and don't sweat whether it's 46 or 49 grains.

 

[SuperCub]

Paul, assuming at least a 22" barrel, loading the Roberts to modern pressures will get at or almost 3200 fps with a 100 grainer. Use the chrony and don't sweat whether it's 46 or 49 grains.

Yes, it is a 22" bbl, and the chrony goes tomorrow.

I'd be happy with 3000fps and good consistant accuracy.

 

[Eagleye]

Paul; In a 24" tube, 3300 is about max for the 100 grain pills, and about 3050 for the 117-120 grainers. So if you knock 100 fps off those for your 22" tube, as RickF mentioned, you should be in the ballpark with your 257 Roberts. Enjoy it, It's a great chambering. I used RL22 for the heavy bullets and XMR 3100 for the 100's with excellent accuracy. IMR 4831 or H4831 should work with both weights just fine. Regards, Eagleye.

 

[SuperCub]

I guess I should clarify.........

I was quite surprised to find that I had gone to about two grains over max with no pressure indicators at all. I was wondering what others were loading for and if they had gone as high as 50gr/IMR4831. I am more interested in accuracy at a reasonable velocity than trying to turn it into a 25/06.

The manuals call for about 45,000psi chamber pressure, which is low for a Remington 700 action considering the 270 goes for over 50,000.

Also, this 257 is on a long action, with the throat set up to accomodate a 3" OAL.

 

[SuperCub]

Back from the range......... Took the chrony and the results were a bit surprising. I tried up to 50/IMR4831 with Hornady and Remington 100gr SPs. There was no problem with bolt lift at all, no shiny ring at the case head and all primers were still rounded. I never thought you could get 3300fps with a 257Roberts.

Hornady 100gr SP

L to R All velocities are averaged.

#1 48.5 3132fps
#2 49.0 3212fps
#3 49.5 3318fps
#4 50.0 3281fps

Remington 100gr SP

#1 48.5 3162fps
#2 49.0 3252fps
#3 49.5 3240fps
#4 50.0 3300fps

 

[RickF]

Paul,

I'd be calling it good at 49 grains and 3200 fps. The Remington and Hornady bullets you are using are soft with short bearing surfaces which helps, but I think you're up in presssures at 3300 even if the primers look okay. Especially when I see the higher charge producing lower velocities, I'd be nervous.

The 25-06 tops out at 3400 or so, so keep in mind what you were looking to achieve in the first place.

Best,
Rick

 

[prosper]

As mentioned, the Roberts was standardized at a much lower pressure than modern firearm actions are capable of handling. +P loadings are quite common and safe (in a modern action). The 257 AI is also a very intriguing round as well.

The problem I have with the Roberts is that it is based on the x57 mauser case, which is an intermediate length. Which means it's almost always found in stardard-length actions. As long as you're going standard length, why not go 25-06?

 

[303carbine]

257

Hey SC, I would bet that the 257 shooting 100 grain Nosler Partition's would make a moose real sick fast. With my old 250 Savage I have dumped a few big Mulies and some big blackies as well so the 257 should do it with more authority for sure. This is what deer and blackies do when I shot them with the 250 Savage..... and then croaked.
Hmmm, we need a croak icon perhaps a bang flop icon too.....

 

[Mike]

I've got a book on loads developed for the 30-06 (A Handloader's Odyssey by Stan Watson) and in it the author used a strain guage to estimate pressure. He didn't detect any traditional signs of too much pressure until 70-80 kPSI. At 68 000 PSI, primers still looked normal. Loads left an ejector mark starting at 73 000 PSI. These tests were done in both a winchester model 70 and a remington 700.

His opinion is that if you're seeing bad things on your brass, the pressure's already gone way too high.

 

[SuperCub]

Paul,

I'd be calling it good at 49 grains and 3200 fps.

I totally agree!!!

I'm not looking to make this thing into a 25/06. I guess I just wanted to know the upper limits, in the name of research of course.

 

[SuperCub]

The problem I have with the Roberts is that it is based on the x57 mauser case, which is an intermediate length. Which means it's almost always found in stardard-length actions.

I had this rifle built on a long action so I could seat the heavier bullets out to a 3" OAL and not take up too much powder room. With a short action, you don't have this option.

As long as you're going standard length, why not go 25-06?

Why not a 25/06?? ...... I just like the old "classics". Simple as that!