My barrel is a 21 inch 1:10 twist and all of the reload books test with 24" to 26" barrels.

Generally speaking would you want to use a faster or slower powder with the shorter barrel, or does this not apply. I was always under the impression to use the slower powders with the heavier bullets in a caliber???

I have IMR 4064, IMR 4350, and H-335, although I see no data for H-335.

I tried 39.5 gns of IMR 4350, CCI-200 primer, WW Super and Nosler 100 gn Ballistic Tips. The groups were 3/4 inch @ 100 yds with crappy mil 2-stage trigger, but the velocity was 2606 fps, which is well below the 2820 fps in the book with the 24" tube.

ETA: The gun is built on a 1939 Turk mauser, large ring 98 with the longer front receiver ring and small ring barrel thread. I have no issues with using +P data or loads in this gun. I assumed that Sierra and Noslaer had +P data in their reload manuals???

quote:

Generally speaking would you want to use a faster or slower powder with the shorter barrel,

Faster powder will give you less blast. However slower powder may still give you the highest velocity.

For what it's worth QL calls that load as 2625fps and a very light load

It is a light load. I use 117s and 43 grs of H4350 in my 22" version for 2750 fps.

Gees Nosler's books are some kind of conservative and Optimistic!!! I have volumes 1,2,3,and 4.

Well at least i know I can go up a bit. I will stick with IMR 4350 for a bit. I did load a few @ 40 gns and the numbers were twice as good as far as SD and ES, the velocity was 2644 fps avg, but the groups were double the other loads. I don't have the best trigger in the gun. I was just given the gun and then a friend gave me a brand new A&B F14 barrel for it as well.

QL says around 43.5gr Imr4350 for max for the lower pressure Roberts Loads.

I used IMR4064 with 100gr bullets with good results, and with shorter barrels I like to go with slightly faster powders as well. The Roberts is one of the old rounds that data is usually really conservative for due to the old rifles. In a modern rifle +P loads can be done quite safely.

Just for some more boots on the ground references, my sons .257 with a 20" barrel really likes max doses of IMR-4064 and 100 grain bullets and my 23" barrelled .257 really likes 117 grain bullets and 41.5 of IMR -4350 this gets 2825 FPS.
Both the above loads are at or under .5" at 100 yards.

OK here are some more results; remember that the crappy, heavy 2-stage military trigger is installed. I don't put a whole lot of weight in the groups sizes. Numerous loads were tested and all put 2 within 3/4" with a third a little over an inch from the other two. The F14 contour barrel is very light and is hot after three rounds. This is a no frills hunting rig and 3 shot groups are realistic for the field.

I am thinking that 44.0 gns of IMR 4350 is the upper limit as far as pressure. 44.5 gns only yielded 9 fps more than 44.0 gns.

Here are 44.0 gns results: Velocity 2930 fps, ES 17.02, SD 8.48; 2 shots 1/2" apart the third about 1-1/4 to the left of these two.

Tightest group was a solid 3/4" group with 43.0 gns of IMR 4350; Velocity 2835 fps, ES 35.16, SD 17.77.

I am going to use one of these two loads. What are your opinions. Go with the Chrono or go with the group? Go with higher velocity???

I'd pick accuracy over a bit of speed personally.
But I'd recommend at least dressing that trigger and maybe a Wolfe spring.

If the rifle will consistently shoot 3/4" with the 43.0gr load I, myself, wouldn't look any further.

I'd go with what BigNate and craigster said. You can play with seating death to tweak your groups if you'd want.

Personally 3/4 of an inch is plenty sub minute of Whitetail for me!

The powders that give the highest velocity in long barrels will also give the highest velocity in short barrels. They'll just be a hell of a lot louder. I only have two rifles in .257 Bob, one with 22" barrel and one with 26" barrel. The 26" gun is a tack driver but the 2" has only done 1.25" at best. Still playing with that one. WMR (long discontinued works fairly well but IMR4350 doe a bit better for accuracy in my guns.
Paul B.

For many years I used nothing but one or the other 4350s. With the shorter barrel I'd be tempted to look at one of the 4064s or perhaps H-380. A near max. load of H-4895 wouldn't be all bad. roger

Another good powder for the Roberts that often gets overlooked is 3031. It seems to me it was accurate but was not the fastest. When I first started loading for my Roberts I was looking for max performance, so I started looking beyond it. I wouldn't be afraid to revisit it in spite of newer powders.

I haven't tried nor given up on IMR 4064 yet.

I didn't phrase my last posting very well.

Would you trust the chrono numbers - lower ES and SD over smaller actual group size?

I'm using 39gr of Varget under a 100gr corelokt bullet, in my 20" barreled 257Rbts and getting 2935 fps and groups right at 1" at 100yds...

Had good luck with IMR4064 too, but Varget is a bit better in my rifle...

Z

I don't know much about calibrating a chrono.

Let the rifle tell you what it likes. Keep detailed notes tgo actually track how it shoots. If you start with a perfectly clean barrel it may start shooting it's best groups after two or three shots, then again it might shoot best dirty.
Accuracy has much to do with harmonics of vibrations and barrel whip. Consitant bullet exit from the bore at the same harmonic node is going to be the most consistant.
All that said, if one load has low deviation it is consistant load wise but may not be letting the bullet exit the barrel at the optimum point.

Here's the truth. How small is the game you're using it for? How accurate does it need to be to be confident whith it? I think if you were to really check things out, including the trigger, then go back to the 44gr load and play with seating depth or even a primer change, you may find it to be plenty accurate. I have a .257 Roberts with a very light contour barrel that heats up very fast. The first two are always close together, the rest open the group up. It kills with the first shot.

How does yours do firing one shot at a time from a cold barrel? Even over several days, shoot one shot and let, it cool completely. You may be surprised how accurate it is.