I have tried for some time now to get my pre'64 M/70 .257 Roberts to shoot Nosler 100gr. Partitions to no avail. Has anyone else had similar troubles and were you able to find a load that would shoot accurately? I am using WW brass with CCI primers, powders include IMR 4064, IMR 4350, Varget, RL-15 and H4350. I have not played with seating depth, I am seating to the COAL specified in the Nolser loading data, I have heard that Partitions may have to be seated a little deeper to be accurate. Seeking your experiences and load data that may work.

Will your rifle shoot other bullets to your satisfaction? If so, why not just change to that load.

Unfortunately, 257 Roberts chamberings are all over the place. I had a Ruger tang-safety Roberts which had a very long throat. It was hard to get any short bullet to shoot well. My current Roberts is a rebarreled Savage Axis. It has an E.R. Shaw barrel with a very short throat. Loads for one would be a poor choice for the other.

Try 3031 it might be your ticket with the Bob.

Some rifles are pretty picky on seating depth. Take one of the 4350s and seat out to touch the lands. From there, shoot a group or two, turn the seating stem half a turn down and try another couple groups. Keep going till you find what you want. I have one rifle that while doing this I watched the groups walk around the target counter clockwise. Group size expanded and contracted as I approached and passed each node. Once you find the depth that works better, turn that seating stem +/- quarter turn for fine tuning. Some guys go a few thousandths at a time, I figure if a node is that critical it's too picky for normal use.

That goes for powder charges too.

Have not tried the 100g Partition, but here is what works in my .257 Roberts with WW +P brass and +P loads.

Note that my Roberts is a long action with lots of free-bore and some of the bullets are seated longer than SAAMI - COL is determined by a minimum full diameter/full caliber seating depth and magazine length. Most loads couldn't touch the lands with a stick but all are very accurate (MOA or better).

3606fps - 75 g VMAX / H4895
3233fps - 100g TTSX / H4350
3163fps - 110g AB / H4350
2904fps - 120g Partition / H4831SC
2947fps - 120g A-Frame / H4831SC

Thanks for the tip regarding IMR 3031, it produced a great load in my .35 Whelen hope it does the same in the Roberts.

Just skimmed the thread .... have you tried hybrid 100v ? If not it may be worth buying a pound

I have tried 100V although not an extensive trial. Will continue to work with it while loading some IMR 3031.

A load I got from Mule Deer's writing is 46 grains of H4350. This load puts the 100 grain NP into a 3/4" group from my 98 mauser.

The owner of the LGS gave me a sample of H4350, I'll have to try Mule Deer's load. Thanks for posting the tip.

Our Mauser 98 loves 117 grain Hornady Round noses at a slower velocity (2650)! Imr 4350 Cci 200
I mean like quarter inch group at hundred yards!!!

I have a very picky No.1 Bob, curious to try some 3031 myself now..

I have a very picky No.1 Bob, curious to try some 3031 myself now..

My best luck with 100s has been with 47 to 48 grains of H4831. Match primers made a huge difference for me.

Have you tried the Berger OAL test? I use it for any new load, irregardless of previous results.

http://www.bergerbullets.com/getting-the-best-precision-and-accuracy-from-vld-bullets-in-your-rifle/

Alan

Best accuracy with 100 gr bullets in my 260 was with IMR4064 and CCI BR2 primers. With the 257 and 260 being rather similar, I’d try the 4064. 120’s work best with R17.

gunswizard,

Generally .257's will indeed shoot 100-grain bullets pretty well with 46 grains of either IMR or H4350. However, that's a relatively mild load, even though it's listed as max in some manuals, because of the low SAAMI pressures for the .257.

Have often found Partitions to shoot better when the powder charge is cranked up some, essentially another version of the advice Gail Root (former head bullet designer for Nosler) suggested, using a slightly faster-burning powder. Extra pressure tends to expand the exposed rear core in Partition, helping them fit the barrel a little better.

Just as a comparison. Nosler Partitions shoot only so so groups , 1 1/2" at best in my Savage 260 Rem. The Barnes 100gr TTSX which likes a long jump shoots almost one hole groups.

Try a heavy for caliber bullet such as the 115 BT,117 Hornady,120 gr and see how your rifle likes them.I know this doesn't help with shooting 100 gr PT,but it will give you an idea of what your rifle likes.

I have a custom small ring Mexican Mauser with a Douglas barrel in 257. She absolutely loves 42.5 grains of IMR-4350 with a 100 grain Partition. WLR primers make her hum right along....the only rifle I've ever had that didn't prefer 210M's. She is a rather strange rifle in that I've never had to trail the first deer ever with this rifle...not one. I've shot hundreds with this rifle. She was a gift to me by a man that was a second father to me of sorts. He was dying of cancer and it was gifted to me before he passed. His funeral was on the Thursday before our rifle opener on Saturday. I was a pallbearer and knew as I was taking him to the cemetery what rifle I'd be carrying in two days....I knew I'd have some luck. Sure enough, I had been in my stand about 15 minutes on that cold morning and low and behold a nice buck shows up at about 75 yards away. With that buck, this rifle's incredible string of one-shot, DRT, kills began for me. The biggest buck I shot with her was a huge 8 pointer scoring in the 140's that dressed at 240#. DRT. She's a wicked little gal and always shoots under a half inch at 100 for me.

Good luck with your rifle.

My Roberts is on a re barrelled Montana ASR action that used to be a 270. I did try some 110gn ELD X in it and got them up to 3,091fps with 47gn H4350. But the rifle seems to prefer the 117gn SST with 48.9gn H4831SC. That load killed a big boar on its first outing at 178 yards DRT. No movement at all. Sometimes the Roberts just won't shoot shorter bullets.

That's akin to reading about a shoe size.

Shaking my head...and laughing!

Hint..................

WTF would you know Dip Stick except how to muck up a thread with your gibberish. Hint and laughing at your pathetic crap so go right ahead and shake your head I can hear the rattle from here.

I have more issues with the 85 BT than than the 100 NPT, dunno why.





But sometimes the shorties work OK.



1/4 bores can be a little curious like that.

With a favored powder, try a modified Berger OAL seating test. Berger has you test something like .005", .040", .080" and .120" off the lands in 3 shot groups; 12 round test. When I have a rifle where I may have a potential powder charge that would compress the living heck out of the powder, I run .005", .030", .055" and .080" (.025" increments). It just might point you in a direction that as a minimum, tells you what OAL your rifle likes with THAT bullet.

Alan