i have a .257 weatherby on a 700 action that i am getting ready to rebarrel and was wondering if anyone had ever played with something like a 25/7mm mag , 25/300 win mag , 257 stw or maybe even a 257/300 ultra i want to set it up for the 142,156 wildcat bullets any pros , cons ,twist recomendations i would be happy to hear thanks for your help
Brian you will love the stw round, I am shooting the 110 accubonds at 3700 and could get more speed if I really wanted to push things. I have used the 125 and 130 bonded wildcats had good results. I had Bill at Summersville make mine up. aka pinecrest if you know anyone from the tactical club in Houston they will know of him. You would need to go with at least a 28 in barrel would do good with a 30 no need for a break as my rifle kicks like a 22-250 with a #5 shilen 1 in 10 twist. hope this helps oldfamily
just get 7 stw brass and resize in the 257 dies. Bill has my reamer as we speak. the only thing bad is that this is the last year that he will be working on rifles, never have been to the club at houston know Bill makes a lot a 338 lapua mags for people in the club. I found out about chucks shoot too late to go. We know the same people I bet you get items to reload with from Will's. I got load data for the stw if you need it.
Brian, I also have a 257W on a Rem 700 action, but with a Krieger 26 inch 7 twist (3 contour) barrel.
I have only tested the 156 grain wildcat so far, and although it gave good accuracy, the Norma 257 brass is soft and restricts me to about 2,900 fps. This is only 70 fps more than my 25/06AI achieved with the same bullet in a 24 inch barrel.(19 grains less capacity)
Kirby and I both thought that I should be able to get 3,000 fps with the 257W case, but it won't happen with Norma brass.
Several weeks ago, I bought some 300 Winchester magnum (Remington brass)and necked them down to 257W, neck turned the cases and then annealed. The cases had a capacity of 85.2 grains compared to 87.8 for Norma new 257W brass.
Today with 300 WM brass, and using AR2218 (H50BMG in US), I worked up from 67 to 70 grains with the 156 grain bullet, and the results from a velocity view point were more encouraging. Although the necks on some cases didn't expand correctly, I achieve 2,984 fps with the 70 grain load, and probably could have gone a 1 grain higher as there were no extractor marks, primers were starting to flatten, but bolt lift was still easy.
I will re-anneal the case necks that didn't expand correctly, and retest using the 156 grain bullet at 300 yards and see what pattern emerges.
I only have about 40 left of the 142 grain ULD's at the moment, but will also test those in the coming weeks.
The 25/300WM and 257STW should produce velocities with the 156 grain ULD that are somewhere between 2,980 of the 257W and the 3,350 fps of Kirby's 257AM. Hope the above is of some help. Regards, Brian.
Do not want to hijack the post, just a quick question, were your test loads with the 300 WIN cases the first load in those cases? If so, the flattened primers may simply be a slightly loose headspace situation and once the cases are fully formed this will go away if that is the case.
Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.
Brian , I have a buddy that shoots a 25-300Win mag and I have to tell ya its a n awsome round it'll flat smoke the 257Wby and run realy close to the 257STW depending on the throat and barrel length.
My friend used Lapua brass and 115gr Nosler Ballistic tips and has great results on deer and hogs out to 600yds , it'll shoot alot farther but he doens't have the place to hunt that far.
My vote goes to the 25-300Winmag ,better brass , slightly shorter OAL will allow you to play with seating depth a bit more and the barrel life might be a bit longer than the STW due to it using less powder.
I'd also get it in one of the barrel makers that makes the 5R rifleing