.257 Roberts help please!

[Handsome Rob]

I'm about at my wit's end with this damn Kimber.
I was really wanting to shoot 100gn bullets, but it looks like that isn't in the cards. I've tried Partitions, Core-lokt & SGKs. I know there are others, but these 3 were what I wanted to work up for (pigs & bigger, range time & whitetail)
I've tried so many combinations around the 'magic' load with IMR4350 is not even funny. Nothing from 43 to 47gn will shoot under 3" whatsoever. I've dropped below book minimum to way above & nothing seems to do better than 3". I thought I'd found a happier spot at 46, but my last range trip slapped them all into 3" again.
I'm not seeing any group shift, all group centers are consistent (it's not the scope or mounts) it just doesn't seem to want to shoot 100 grainers.
Doing a bunch of online snooping, it turns out that this seems to be common, even with the 1:10 twist. They seem to like <90gn and >110gn. The mid weights don't get any love.

So. Has anyone had any success at all with 100gn bullets in the Bob? If not, what's the consensus on 80gn TTSX on accuracy & game? I've read a ton of very positive accuracy reports on the Barnes/4350 combo, but no dead stuff reports

[gregintenn]

We have 3 custom Mauser 257 Robert’s rifles. No idea of the twist rates in the barrels. Two are very accurate with Sierra 100 grain Game Kings atop IMR 3031. The third prefers 87 grain bullets. 
 

I have had luck in some rifles adjusting the bullet seating depths. Some prefer longer oal while others shoot better with a shorter oal.

I guess you’ve tried free floating your barrel and/or glass bedding? Crown look ok?

Sometimes you get a rifle that just won’t shoot.

[Handsome Rob]

36 minutes ago, gregintenn said:

We have 3 custom Mauser 257 Robert’s rifles. No idea of the twist rates in the barrels. Two are very accurate with Sierra 100 grain Game Kings atop IMR 3031. The third prefers 87 grain bullets. 
 

I have had luck in some rifles adjusting the bullet seating depths. Some prefer longer oal while others shoot better with a shorter oal.

I guess you’ve tried free floating your barrel and/or glass bedding? Crown look ok?

Sometimes you get a rifle that just won’t shoot.

It's brand-fire new. Maybe 100 rounds through it. The barrel is floated, although it's pencil thin (Kimber Hunter) I'm limited by Kimber's short magazine length. Right now I'm so close to the max length, I'm getting the occasional hangup in the box. I must admit though, I haven't actually tried SAAMI spec oal.

Edited March 18, 2022 by Handsome Rob

[gregintenn]

Thin barrel=one shot, let cool, one more shot, repeat. They do have a tendency to wander as they heat up. I’d try a shorter OAL and see what happens.

 

Dad once had a model 700 Remington mountain rifle with a pencil thin barrel. It wouldn’t shoot 3 shots quick very good, but the first shot from a cool barrel always went into the exact same spot. It sure was a dream to carry in the woods.

Edited March 18, 2022 by gregintenn

[Quavodus]

I know you want to shoot 100 gr. but, try some 110, 117, or 120 gr. A friend had a .25-06 that wouldn't shoot 100 gr. But, loved 117 and 120 gr. 

[gregintenn]

2 hours ago, Quavodus said:

I know you want to shoot 100 gr. but, try some 110, 117, or 120 gr. A friend had a .25-06 that wouldn't shoot 100 gr. But, loved 117 and 120 gr. 

I found the same with my 25-06, but all our 257s like lighter bullets.

Mt 250-3000 chambered Savages only like 87 grain bullets, and short 100 grain Remington core locks.

Edited March 18, 2022 by gregintenn

[Quavodus]

Don't most of the Savage 99's in .250 have a 1-14" twist?

[gregintenn]

1 hour ago, Quavodus said:

Don't most of the Savage 99's in .250 have a 1-14" twist?

I’m not sure, but the older ones were known for a slow twist rate.

I guess the model 20 would be the same, but don’t know for sure.

Edited March 19, 2022 by gregintenn

[Quavodus]

It's seems like I remember seeing in an older Lyman manual where they had there .250 savage load data, and had a Model 99 that had a 1-14" twist. But, maybe I'm having a brain fart.

[gregintenn]

1 hour ago, Quavodus said:

It's seems like I remember seeing in an older Lyman manual where they had there .250 savage load data, and had a Model 99 that had a 1-14" twist. But, maybe I'm having a brain fart.

You are probably right.

[Quavodus]

19 minutes ago, gregintenn said:

You are probably right.

About the brain fart? 

[Smokin45]

I loaded some 85gr Nosler Ballistic Tips and Hornady 117gr Round Nose for my Dad many years ago. He shot a Rem. 7600 in .257 Bob.  Loaded the 117gr using 34gr of IMR-4064.  He liked the mild recoil and accuracy of the load. He kept me busy. 

[gregintenn]

Any luck?

[Handsome Rob]

8 minutes ago, gregintenn said:

Any luck?

Still looking for different bullets to play with. I'm almost on the verge of putting in an order with Hammer. I actually pulled the scope off the rifle to put on my .223 I have another on order that should be here in a couple of weeks. I'm really in no rush. Hunting season is a long way off & I have plenty of alternatives

[Mowgli Terry]

There something in the mix that is not right. That gun may need to get back to Kimber. One of the go to powders is 4350. You may have a problem outside the rifle. That would be scope and/or mounts.  Shooting hundred grain bullets in a 99 with 1:14 twist  can be a horror story. I did not read about this in a gun rag.

I go along on checking the twist. Somebody may have ordered a special with 1:12 twist. Also, do pay attention to COL related to throat.  Unless somebody buggered your rifle up there is no earthy reason that rifle should not perform very well. I've got three 257 Roberts  rifles here. Each is an MOA firearm.  To start with I'd suggest starting with a 100 gr bullet.  My go too bullet is a 100gr. Sierra  flat base with 4350.. Keep it simple. Keep jumping around with these bullets will put you down a rabbit hole.

 

Added: When you are working up a load try to change one thing at a time.  Otherwise, If you get what you want what component really made the difference. Jumping around from bullet to bullet  mixed is crazy making as you change powders.  Also. take a look at Reloader 17 and Varget. Also, consider changing the scope out. Torque mounts and rings and action screws. 

 

Added: Just added a Winchester Featherweight in 257 Robert's.  That makes #4. Get interested in this nitch stuff and it will come out of the woodwork. Should have that one running shortly,. Hope OP's rifle get straightened.

Edited April 15, 2022 by Mowgli Terry