Home Forums Hunting & Shooting Hunting Rifles Kimber 257 Rob OAL constraints

I have a Kimber Select 257 Roberts that is more accurate with heavy bullets compared to light.


Shoots 117 SGK's very well.

Thanks Tom, Sam, etc.

Good info and thread, reminds me of the old days. Ask a legit question and get legit answers from guys that have experience....

Dave, I just went and looked at notes...



257 Roberts


44 grains H4350

117 SGK

Remington brass

CCI 200

2.800" COL


And according to that batch of brass it was on 9x firings but of course work up accordingly.

I guess I fall into the camp of trying more bullet / powder combos before modifying things. Both of my Kimbers (257 Roberts and 325 WSM) seem to be particular about what they like. Lots of loads in both shoot well enough to kill stuff, but they both have one load combo that stands out. I was a bit frustrated with the 257 until I tried the 100 TTSX with RL19...

I have 100TTSX and R19. I may have time to throw 3 together before Friday...I have some sort Sierra in my 25 cal box...thinking they are 100gr GK or Prohunters.

I have a Kimber MT in 25 Bob and have the same issue with mag box length v L&G location. Mine likes to shoot 1.5" groups - until I tried Ramshot Hunter. I run 47.5 gr under a 115 Partition and a Fed 210 seated to 2.82. A couple of things - first 47.5 is a +P load. It runs the 115 at 2900 in my rifle. Second 2.82 only has a couple thousands clearance.

My gun also likes H4350 and likes to shoot 4/5 into 3/4" and 1/5 to make a nice 1.25-1.5" group. The Hunter keeps them at 1". I haven't tried other bullets because ID rather have a 1.5" Partition group than a 1/2" cup/core bullet. I've shot enough deer with cup/core at 2900+ to know what is going to happen when bullet hits real bone. I had planned to try 100 TTSX if the Part didn't shoot. I'm cool with 1-1.25" groups in that rifle. It works well for its intended purpose.

In previous 25 Cal rifles I've had struggles getting 115/120 gr Part to group much better than 1.5". Conversely the 100 TSX has been stellar. I hated the on-game performance of the TSX which is why I don't use them now. I'm hoping the early issues have been resolved and the TTSX is the answer. I may try TTSX in my gun. I expect they'll shoot well - they have in the other 25 Cal guns I've owned.

Good luck and let us know what you find.

That... Modern speeds for the Roberts is right at the 2800-2850 area.. No one need to go further.. Personally, it's one of my favorite rounds and I was lucky enough to obtain a M70 FWT about 20+ years ago in pristine condition and it's just a total pleasure to shoot..

Snuck out to the range...getting better.
100BT and R17 shot 1" for 3 at a TOO hot 3180
80TTSX and H4350 shot 1.25 for 4 at a warm 3280

I will back those off a half grain or so and see....

When you say "too hot" and "warm" was the rifle telling you that, or was that your impression of the chrono output?

Both. Stiff extraction and fast speed

You should be able to sling the 80's at 3400fps without breaking a sweat

The reason I asked was comparison with Hodgdon 6mm Rem data for the same case with a smaller neck. The 257 should be capable of at least the same speeds.

Good analogy!

Will try the 80's R17

I am also concerned on the explosion factor with a 100BT doing 3100+

Try 100 grain Sierra Pro Hunters and H-4350 before you give up.

I am not giving up as I now have some definite promising loads....

According to my latest book, you're right at max speed for a 100 gr. boolit.. But if you're getting a bit of bolt-lift issues at that speed it's best to back it off about 50 fps and see what happens.


Oh, and I should have noted in my post above that I was referring to 117 gr. bullets.. My bad.

45grs R15 with 80TTSX - 3500fps (hot) 1.25" 4 shots (44 next time should be perfect at 3400)

45.5grs R17 with 100 Hornady SP - 3180 (warmish) 1" 3 shots (first 2 in one hole)

45grs R17 with 100 Partition - 3150 1.25" 3 shots (good load and not hot)

It's good enough now with any of these and will probably abandon the BT as these are all known to be tougher.

Thanks guys!

Thinking about a 243 Montana now.............

Anyone tried the 90 gr. GMX bullet? My Bob is a 700 Mtn rifle so I have COL issues too but I have had no issues shooting 117 Game Kings, 115 Partitions and 100 BT's & TTSX accurately. I did not get good results with the 110 Accubond but I only tried a couple powders and still have a few 100 on hand to try with other powders.