257 Roberts Modern Data

Discussion in 'The Ammo & Reloading Forum' started by gdcpony, Mar 23, 2012.

  1. gdcpony

    gdcpony New Member

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    I have asked similar before, but now I am about to load my test loads this weekend and hate going in blind.

    Here is the loading data from Hodgdon's website for my selected powder and bullet for .257Roberts. Notice that it is a conservative load meant to be safe for older Mausers. I am loading for a modern action and with +P Brass. I am looking for loads to make the most of the round's capabilities. I would like to see if 3200fps (maybe 3250?) is attainable with this bullet/powder for a longer range predator/deer load.

    Bullet wt/ type- 100 GR. SPR SPBT
    Powder - Hodgdon H414
    Caliber- .257"
    OAL- 2.770"
    Starting load/ Velocity/Pressure- 44.0/2919/33,600 CUP
    Max Load/ Velocity/ Pressure- 45.0/3098/44,500 CUP

    I know precision will dictate the final load, but I would like a good modern maximum. I want to load for the strongest load that holds a decent group. If I can go up .1gr and give up just .1" in group then I would if I can put a bit (worthwhile and noticeable via chrony) more energy on target.

    Just looking for input.
  2. Bindernut

    Bindernut Well-Known Member

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    How long of a barrel do you have? 22"
    If so, then you're not going to see 3200fps from a straight Roberts case. Maybe 3100 but more than likely 2950-3000 before you start seeing max pressure.
    Remember, Hodgdon's data is developed in pressure barrels and not in production rifle barreled actions...plus they don't list the length of tube they're shooting out of either. From what I've correlated against my barrel lengths and velocities, I'd suspect they use either 24" or 26" test barrels for most of the standard cartridges.


    With 100gr Sierras, the best I ever got with acceptable pressure levels was 2925fps (from a 22" Ruger 77). 2900fps was the consistent max vel I got from my Rem700 in .257Roberts.
    H4831 and RL19 were the two powders that I had the best results with. WW760 (pretty much identical performing to H414), like most spherical powders, was spotty in cold weather for me. Velocity was real inconsistent. Since deer season is pretty much cold weather in my area, 760 was unusable in the Roberts for me. YMMV in your rifle and your locale though so you might as well give it a try.


    My opinion...if you want max retained downrange energy, go with a 115-120gr. You'll be starting out witrh about 150fps less at the muzzle, but because of the higher sectional density of the heavier bullet it'll carry it's energy out farther than a 100gr will.
    You're not going to lose much in flat trajectory with the 115-120s at the useable range for medium game like deer & antelope compared to the 100s.
    I was a die-hard 100gr shooter in the .257 bore for quite a few years until I started messing around with the .264s (6.5Swede and 6.5RemMag). In the .264, once I saw the terminal performance of the 160gr and 140gr compared to the 120gr I decided to try it out with the .25-06 and .257 too. That made me a convert to those long, skinny bullets.


    If you want a super flat shooter, move up two steps (skipping over the .25-06) to one of the .257 magnums. Enjoy the .257 for what it is...a nice mild-recoiling, mid-power medium bore that's versatile enough to take everything from varmints to elk.
    Last edited: Mar 23, 2012
  3. gdcpony

    gdcpony New Member

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    I will rebarrel for the AI version someday. But not yet.

    I have a 26" barrel.

    I am in NC right now (Marine) so deer season cold means 40's.

    I use the 257Roberts as a replacement for a .243. I am sure it could out perform it with good loads, but proving it...
  4. Bindernut

    Bindernut Well-Known Member

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    If you've got a 26" tube then you might get near that 3100fps mark with 100gr bullets. Not sure about 3200fps...maybe. That's not a common length tube for the Roberts but it should help you out with the extra fps.

    Temps in the 40s shouldn't be a problem for double-base (typically spherical) powders like WW760/H414.
    I mostly noticed the velocity variation getting very apparent down around the single digits and low teens.


    I had another thought on this at work last night too. Have you considered trying Hodgdon's new Hybrid 100V powder? It's right around the same burn rate as the two 4350s...which is pretty darn close to WW760/H414...but is posting higher velocities for the reported pressures. They've got data online for that powder in the Roberts.
    I'm thinking about trying it in the .25-06 and 6.5x55 but I haven't found it on the shelf locally.



    I agree, there isn't very much difference between the .243 and the Roberts when it comes to game performance except for the ability to bump up to 115-120gr if you choose.
    As for proving the .257 bore is better than a 6mm? I suppose if the deer notices the difference he might tell ya, but I doubt it. :D I know they both work just fine.
    You sound like me...I enjoy having those "oddball" cartridges that you just can't buy ammo for at Wally-World.

    Be sure to post up your results too, good or bad. I'd be interested in the range report on your load.
    Last edited: Mar 24, 2012
  5. gdcpony

    gdcpony New Member

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    Unfortunately the rifle wasn't ready. I don't rush good smiths either. So I am doing this: Load from 45-47gr two rounds each in increments of .1gr. I will shoot them over a chrony and check for pressure signs. Once I notice that I will will back off .2gr and consider that my new load max for development.

    47gr is the listed max for 414 in a 25-06 so I should hit pressure before then. If I don't see 3200 on the chrony before I have to back off then oh well. But to me it seems attainable figuring I have at least 5k of pressure and less than 100fps to go (based on my other loads out of the gun, I will be about 50fps faster than the data).

    I noticed Hybrid and it just bumped 4350 out as my next powder to try. It is listing 3200fps with a compressed load of 48g and pressure about where 414 is.

    I love the "mid length" rounds like 7x57 and 257. I want to try them Ackley'd, but money will dictate. I do have an extra action I was going to have done in 7x57 Ackley with a nice heavy barrel, but the expense vs return on that is rather low. So it might be done in 257AI instead. Then I might get this one redone for fireforming!

    Someday I will try a light bullet through this gun and see how it stacks up against a .243 as a varmint gun. I have a friend pushing 55gr pills out of his at 4000fps. He want to see us develop comparable loads on the same bullet weight and see if the 257 can exceed his speed. Umm... not yet. this will be my first loadings out of bounds of book data so I'll take it slow.
    Last edited: Mar 24, 2012
  6. gdcpony

    gdcpony New Member

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    Ok it took a long time to get out there and try them out, but I easily got my 3200fps without any sign of pressure issues. In fact, I only pushed the max listed by Hodgdon's data by .1gr. to get it out of my rifle.

    I went ahead and fired the rest and was at 46.8 gr before I got my first sign. By then I had pushed well beyond my goal at any rate. Extraction was still good and no primer issues either. Just an increase in head expansion over previous loads.

    The loads were loaded to test pressure/velocity not accuracy so I was going to disregard group sizes, but 45.4gr gave an awesome .82" @ 3280fps (average velocity of 5) for me. This was without me going through and doing my usual OTL (off the lands) testing and any special brass prep. I will be loading more of that to check out.

    I plan to re-bed and re-scope the rifle as it is my project gun as well and was wearing a Konus 1.5-5 shotgun scope and I plan to shoot to 500 on varmints with this thing eventually. Maybe I can get .5 out of this old thing then?
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