Skeeter,
Well, out of a 26" barrel you are a tick low in velocity but not by alot. It may just have to do with the barrel more then anything.
THe rifles I am reporting near 4000 fps with in 26" barrels are from 3 groove Lilja barrels which I have found to produce 50-75 fps more velocity with similiar pressure signs compared to a 6 groove rifling system.
Also, I have tested both the XLC and TSX in the 257 STW and did not care for either. THe XLC was actually faster then the TSX but neither grouped well enough for my liking for shooting like you are doing.
For the STW though, they are very stout to survive any impact but I still do not recommend them unless they shoot very well.
I have heard of report with these bullets getting 4100 fps in 28" barrels but have always found them to run about 100-200 fps behind the likes of the ballistic tip and Partition bullets.
There are a few things you may want to try as far as loads go that may get you a little more velocity.
First, are you loading the X bullets close to the rifling origins? IF so you will prematurely increase pressures, back them off 0.050" from the lands and see what happens to accuracy.
If you keep the groups work up your load again in 1/2 gr levels and see where it tops out there. This is another reason I do not care for the X bullets, to **** picking with seating depth for me.
Personally, I would switch to a 100 gr Partition and never look back. I would bet they would shoot better and up to 75 fps faster then any X bullet. You can also coat them of another 50 fps if you like.
They will not hold up as well as the X bullet at point blankk range but with a hehid the shoulder shot, they will work great on deer and still perform extremely well at long range.
As for powder, thats a funny thing in the big STW. You are using one of the two powders I recommend to my customers for 257 STW rifles I build for them. I recommend Rl-25 and H-1000.
You may want to try H-1000, it is a little quicker burning but will generally get a little more velocity, not much though. Really these two powders are the better choices for the STW.
You may want to go a bit unconventional and try some loads using Retumbo. THis powder is substancially slower then either of the other two powders but will get you out of pressure problems. The only question is where you will top out in velocity.
Also, with Retuymbo, use the Fed-215 primer, not the 215M match primer as it is not as hot as the standard 215 because you will need a hot flame to get the Retumbo to burn well with only 100 gr sitting on top of it.
I suspect your slightly slower velocities are more from your barrel and the bullets you are using then your load.
I would try the partition and see where it will take you. The B.C. is lower but for 500 yards hunting, you have more then enough Horsepower to muscle it out there with very flat trajectories.
Hope this helps a little!
Good Shooting!!
Kirby Allen(50)
