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.257 Roberts, A.I.
MIKE WISKEY
Member, Moderator Posts: 9,972 ******
I just put one of these together and am looking for 'pet' loads, 75 and 87 gn. bullets. anybody else shoot one?
Comments
What exactly did you build and what are setting it up to do?
You can hardly go wrong using H-4350 with any of the bullet weights.
Gun control is hitting what your aiming at.
J/K.
But I am quite fond of 4831 in my .25-06 with all bullet weights. The .257 AI is close to the .25-06 for capacity, so I would imagine powders that work well in the .25-06 will work nicely in the AI.
Save the seals-club a liberal instead.
I have quite a few pet loads for the .257 Rbts. Along the lines of what shooter93 said, for loads right out of the book use standard brass. Use the max of the .257 for starting loads and work up. The old standby recipe for std Rbts in my family (everyone has one)is 41 grs. of IMR4895 behind an 85-87 gr. bullet. That's what Nosler has as starting loads for the 85 gr in AI. Sierra starts at 40.1 (IMR4895)for their 87 gr. The top out loads for these two powders are 47.3 gr. of 4895 and 48.0 gr. of 4064. An old Hornady manual I have shows 43.4 anf 42.2 as max but those numbers are pretty low. Conversely they show more powder in the std. than the AI.
Nosler doesn't have published information for a 75 gr. but Sierra starts at just over 41 gr. of IMR4895 Starting load of I4064 is 40.9(typo?) The top out loads are 47.7 of I4895 and 48.4 of I44064.
On a new note I have been having to go where published information is not. My newest pet load is 42 gr. of VV N140 behind a 100 gr. bullet. I get 3100 fps for that using +P brass in a 20" barrel. That is noteworthy as a short barrel in a .257 really takes away from the versatility of the cartridge...same with the A.I. case, 24" barrel is best.
I use +P brass for all my .257 loads.* I have really liked the Vihtavuori powders so far. Data is limited, and even though the burn rate of N140 compares to 4320 and N150 to 4350 they are not the same! VV produces much more pressure. This is verified where you do have loads published in various calibers and you will see that N150 max's out much lower than 4350 in a given case.
*If you are going to convert +P brass watch for pressure signs sooner. The loads above are for standard brass but I get more velocity out of 40.5 grs. of 4895 in +P than I get from 41 gr. in standard.
Anyhoo, before I ramble on and on about my favorite caliber I just thought I would pass on some of the loads I use. And as always work up to them. -Good luck.
ADDED: 8-13-05
Snellstrom,
Since it's related to the original question I think it's pertinent and not really a hijack. The 42 grs. of VV N140 is right at max. in +P brass for the .257 RBTS. The 20" barrel is the kicker, we always got much better performance in 24" barrels as the case lends itself better to medium/slower (not slowest) powders. That's a known given....a good place to work up from in the AI since there is little information. The Vihtavuori manual covers neither the .257 Rbts or Improved versions of that caliber. My latest Nosler only covers a couple powders in either chambering and those limit their data to older rifles. Sierra has limited their data to 3-4000 CUP UNDER the old SAAMI spec of 45000 CUP in the few offerings they give. This is a great powder to reload .257's with if you stick to the strength of your rifle and work up.
What I found with VV is that in order to find starting loads to work up to, find an extruded powder with comparable burn rate....then take off a couple more grains. VV produces more pressue than American powders.
I found this out the hard way when I pushed a 120 gr. out at 3180 from my 25 WSSM using reduced data from 4350. I had no published information to go on other than relative capacities of closely related or compared cartriges. Needless to say the case was hard to remove from the chamber. The next load was much lighter. I ended up working that up to 40.8 grs. of VV N150 for a much more sane 3005 avg. velocity. -hope that clarifies it a little better.
We have the second amendment so that all the rest are secure....UNK>
Would like to hear more on the vv powder and by the way I'm sorry about hijacking the thread but I just gotta know.[;)]
why chase the game when the bullet can get em from here?....
Got Balistics?
MONEY TALKS mine says good-bye
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