I have a 257 Roberts built on a 98 Mexican Mauser action. I'm finally getting around to working up a couple loads and the only manual I have that lists the Bob is my Speer #12 (4th printing, 1995). I have two sized bullets to play with: 87gr Speer TNT HP (brand new) and 100gr Nosler Ballistic Tip BT (bought these at a swap meet... new old stock #43005). Cases are brand new Winchester brass, FL sized, flash hole deburred and primed using WLR primers.

I have never used 4350 but realize that it comes in three flavors: Hodgdon, IMR and Accurate XMR. The relative burn rates for the IMR and Hodgdon sit next to each other on the chart but in my Speer manual look nothing alike. For the 87gr TNT, H4350 starts at 47.0 and max is 51.0C, versus the IMR 4350 that starts at 43.0 and max's out at 47.0 grs. I have no idea where the Accurate XMR 4350 falls in terms of load data (nothing published as far as I can find) but it sits just below Re17 in terms of burn rate. Funny thing is, Speer lists two loads for the 87gr TNT using Re19 and Re15 but not Re 17...?? I'm wondering if that could have been a typo. I'm also equally perplexed by the load data for the 100gr Nosler projectiles.

I have all three powders, the most being IMR 4350. I also have Re19, H380, N150, N160, N560 as possible choices. This rifle is for my daughter to shoot prairie dogs and maybe a buck someday. She just started college so the best I can hope for would be a prairie dog hunt over a long weekend, hence the lighter bullets in my early load development. Any help using published data would be greatly appreciated.

Brian

I have never loaded for or shot the 257Roberts but have burnt a bunch of IMR4350 and when used in the correct applications it is hard to beat.

Your Speer #4 manual is too old to list Reloder 17 data, as this propellant was introduced after printing by at least a decade. I have never personally used this powder but have read that though accurate loads are easy to find with it, it is found to be very temperature unstable.

When I try to match a powder to a cartridge I look for something that fills the case to +/- 88% load density. This system has worked very well for me for many years of "rolling my own". I shoot for .25 MOA but usually settle on a load that shoots between .5 and .7MOA in hunting rifles.

Thanks Dennis. Looking at the Nosler web site, their published load data for the 257 Roberts for 100gr Ballistic tip bullets using IMR 4350 lists 43.5grs as their max load @ 88% load density. Nosler also lists this as their "most accurate" load... just as you predicted. Contrast that to my Speer manual which lists the same weight bullet using 45.0grs of IMR 4350 as max load. I'll stick with Noslers numbers and your load density

Just as my Speer manual is 20 years old, so are most of my powders (except for 2#'s of IMR 4350). Can you recommend to me a good manual with modern load data? I've also recently started loading for the 300 Blackout. Many thanks!

Brian

Just comparing the 3 4350s in QL with an 87. H4350 calculates 58,000 but 110% of capacity at 51. If you take IMR & accurate to 51 grs you are at 68,000 and 108%. So I would say the later 2 are faster(hotter) than H4350

Issue can also be what pressure are they loading too. QL says Nosler's max gives right at the 51500max. The 45gr puts you in the 58,000 +P range.

Thanks Paul. Right now I've loaded 50 (5x10) cartridges with 100 gr Nosler Ballistic Tip BT bullets using IMR 4350: 41.5, 42, 42.5, 43 & 43.5grs. COAL is 2.78" but I may have room to play with this dim. For now I'm sticking to SAMMI specs and published load data that I trust.

What does QL suggest for the 87's? I have a wide variety of powders, mostly in 1# jugs. Unfortunately I'm missing the ones listed my in Speer manual :/ For instance, I have H4831 but not IMR 4831. I do have some H380 and Re19, both listed but definitely on opposite sides of the burn spectrum.

Brian

I'd try some of that rl-19 with those 100 gr bullets.
and use the faster 4350 with the lighter ones.

With an 87 grain Speer TNT bullet, my Speer #12 manual lists RL19 starting at 47.0 with a max of 51.0C. My other choice of powder on hand is H380 (42.0 to 46.0 max). Can someone please verify these loads?

Brian

I have the same #12 and #13 Speer manuals, loads listed in both are the same, only difference is that newer powders have been added, so yes, whatever is listed is still valid as long as you start below and work up.
A good manual I have found is Noslers most recent, but Hodgdon's online data is very good also, as is Alliant's if using their powders.

Cheers.


PS: I only have data for my 257AI, sorry. I prefer 100gr bullets for everything in mine, I use 100gr Nosler BT's.

For the regular Bob, I've had better luck with IMR 4064, especially with the lighter bullets, than IMR 4350. I think the heavier bullets (over 100 gr) work better with the slower 4350. In my AI Bob, I've had better luck with IMR 4350.

But with that being said, the funny thing is in my daughter's standard Bob, and Nosler 100 gr BT's, I found 43.5 grs of IMR 4350 gave me a sweet spot in accuracy. I'm using Rem 9 1/2 primers in that load and OAL was set to 2.895". This is in a custom bbl'd Savage.

I would expect accuracy to be best near the top of that 4350 load.

I think the reason I'm finding hotter loads in some books than in others is the +P designator. I have a 98 small ring Mexican Mauser and loading with Win +P brass. Is there any reason not to use +P load data in this rifle?

I've also noticed that published load data lists COAL at around 2.780" (87 grain and up) but this puts the mouth of the case just above the ogive (which can be dangerous). Just now measuring, the 100 grain Nosler Ballistic Tip seats at 2.970" before contacting the lands. I think I'll load up another 50 of the 100's using RL19 and seat the bullets .020" off the lands. That will put my COAL at 2.950". The magazine box can handle anything up to 3" without binding.

Any comments, corrections, criticism?... please speak up!

Brian

I recommend sticking with IMR 4350; it was the original and I can't see changing now. I use 4320 with 100 grainers and 4350 with 120s. I use ++++P loads in one of mine as it has a really long throat; others I have to back off a bit. Go to loaddata dot com and you get all the loading data on the planet in one place. Except mine which give above 25-06 performance. Your Mex will be fine. 257 is the best small caliber round ever made but has always been hampered with weak, short, loads. Make your loads as long as you can go in your throat and use that powder capacity.
I don't think +P brass is different brass; just the ammo.

I think the brass marked "+P" has thicker webbing area, and therefore less case capacity. Not really a problem if you develop your load on that brass. But if you develop your load on standard brass, and drop that powder charge in a "+P" case, you may have some pressure issues. And if you go the other way, using a "+P" brass load in standard brass, you're pressure will be lower, and velocity and group size will probably be impacted.

I think all my brass is standard pressure brass, (I have 2 "Bob's", a standard and an AI) and it has not been an issue with developing good hunting loads. I just work up a load like any other bottle neck cartridge.

some years ago I loaded some ammo and experience some peculiar reults which eventually led to a bullet that stuck in the barrel. Since it was a new loading I looked for the lowest published charge from the various load books I had, I settled with one published in an early speer manual. I felt comfortable with that since the bullet I was using was a speer.

I pulled the remainder of the cartridges to check the powder charge and all where identical. I checked the diameter of the bullets and found the to be slightly over published specs

I wrote to the primer company, the bullet manufacturer and the powder company and the load manual company

They all responded
The primer company stated the primer either goes off or it doesn't, it does not half go off
The bullet company stated the bullet was within specs
The powder company suggested I contact the manual that presented the load...which I did

Speer publishing stated all previous manual specs published are superseded by the more current published recipes. Since that load was not published in the current manual I loaded it at my own risk, no liability exists.

There you go a circle jerk of ballistic proportions

quote:

Originally posted by dpcd:
Go to loaddata dot com and you get all the loading data on the planet in one place.

+1 And they keep adding loads.

I highly doubt that +p brass is thicker; that would make it dangerous to use with existing data.
Can someone weigh a +p 257 brass and post it; I will weigh some standard brass and do the same.

You can check out the data here too:

http://www.hodgdonreloading.com/data/rifle

That says for a 257 roberts with 100gr bullets:

H4350 45gr
IMR4350 47.7gr

Highest speed was with Hybrid 100V

Good luck.

I have a Remington M7MS in .257 Bob. H4350 is definitely my powder of choice for this rifle.

I like 47.0 gr. of H4350 with a 100gr. SGK and 44.0 gr. of H4350 with a 117 SGK.

Both loads have proven to be sub MOA accurate in my rifle.

Those loads are for modern actions only. I can't speak for your Mauser.

My brand new Winchester 257 Roberts +P brass weighs in at 12 grams (.40 oz) primed. Headstamp reads:

W-W SUPER
257 ROBT+P

Ok, that is 185 grains (we don't use grams or ounces here for reloading).
Older Super X; 168
Newer WW Super (maybe 10-15 years old;; 183
So, looks like the older WW brass is thinner, but the newer stuff, is the same, regardless of the +P markings.

Thanks dcld --

I used my electronic postage scale to weigh the case. The added primer probably accounted for the additional 2 grains in weight.

No, I weighed them primed. Your postal scale is probably not accurate to within 2 grains anyway.