Originally Posted by SFR292
I'm currently building my first 7mm STW off my Winchester Mod 70 push feed action.
Winchester Mod 70 Action (Originally a ranger model in 270 WIN)
PTG One Piece Bottom Metal
Wyatts Magazine and Follower
Precision Armament Bolt knob
PTG Action bolts
HS Precision Stock
EGW 0 MOA rail
PTG Reamer built to my specs
Still debating on the barrel, it's going to be a finish length of 28", looking a krieger 1:9 standard palma however I have some questions for those of you who already shoot the STW. I was planning on shooting mainly the 139 gr AMAX and some 140's so I was planning on a 1:10 to maintain the high velocities the STW can deliver (3550ish fps) however I've come across some krieger's 1:9 5r, I know this will be good for 168's and even the 180's, however will it over stabilize a 140?
And before it's asked (first thing people ask me when I tell them about my build), I've already opened the bolt face up to a magnum and machined the receiver for the longer magazine. I have 3.825" worth of COL in the magazine so I can use the heavies if I want to.
Thanks again guys. I'm also building 4 other 7mm STW's at the shop right now for other customers as well.
Wow, you have really done your home work, and your equipment list is impressive. Gotta love those Winchester actions too. I have personally fell in love Winchester actions myself. I still love Remington actions as well.
As far as your over stabilization question, I would not worry about that so much. Som makers actually are running a 1-9 twist with no problems. If you go with the 1-10 twist, you may be able to shoot bullets up to the low 160 class anyway. But for what you a are wanting to do, either twist mentioned will do fine. 3550 is really pushing the envelope for a bullet to be able to function, at the terminal end though. And then, there is the barrel life issue of course. So, all else being equal, bullet selection will definitely be a factor.
One last thing to think about is the 3.825 OAL. Given that this cartridge is a free bored chambering, you will now be closer to the throat, which means your pressures will occur slightly quicker then most that are at the usual 3.630 to 3.670 ish OAL. Nothing of a show stopper as long as you build up cautiously to your rifles max, or sweet spot.
That is going to be quite a rifle, and you should have many years of enjoyment from it. Take care of it, and it will not let you down.