270 STW pill advice?

[KyScott]

Ok guys I need some advice after reading the 52 page thread on the long range ABs. If youre were building a 270stw what 150 grainer would you start out with. Ill be running a 26 inch barrel prob 1-9 twist. The reason for 150s and not bigger is to stay as flat as I can out to 500 but if you have heavier suggestions I'm all ears. I dont believe in over kill I want it to hit hard and be accurate whether im shooting groundhogs or get drawn for an Elk tag. Thanks ahead for the advice and take care.

 

[FEENIX]

Ok guys I need some advice after reading the 52 page thread on the long range ABs. If youre were building a 270stw what 150 grainer would you start out with. Ill be running a 26 inch barrel prob 1-9 twist. The reason for 150s and not bigger is to stay as flat as I can out to 500 but if you have heavier suggestions I'm all ears. I dont believe in over kill I want it to hit hard and be accurate whether im shooting groundhogs or get drawn for an Elk tag. Thanks ahead for the advice and take care.

IIWY, I'd go heavier with 165 or 175 Matrix VLD and take advantage of its BCs.

I have done extensive testing with the 175gr. It has a G1 of .6435 and a G7 of .3225.

My friend who is as anal as I am with checking the BC's has tested the 165gr at a G1 of .638, so the G7 profile would be a .319.

I'm pushing 175s beyond 3000 FPS (2993 is my accuracy load at the moment) out of my .270 AI with my Lilja 30", 3-groove, 1:8" ... just imagine that extra powder capacity can do ... but that's just me and I'm sure others will chime in.

Good luck!

 

[KyScott]

Good info Feenix. Couple more questions.

1. Is there a big advantage with a 1-8 over a 1-9?

2. Without me searching the internet whats the average case capacity of a 270 Ackley. Just wondering how much more the 270STW has.

Thanks

 

[MudRunner2005]

Good info Feenix. Couple more questions.

1. Is there a big advantage with a 1-8 over a 1-9?

2. Without me searching the internet whats the average case capacity of a 270 Ackley. Just wondering how much more the 270STW has.

Thanks

The .270 Ackley Improved is based off the .270 Win case, which was based off the .30-06 case. So the .270 Ackley Improved has about .017" wall taper, and with the 40* shoulder, it should hold right at 70gr of H2O capacity (NOT to be confused with actual powder capacity).

The .270 STW is a magnum caliber, based off the 7mm STW, which is based off the 8mm RemMag, which is one of the many .300 H&H Magnum variants. it doesn't have an improved design. However, being the large magnum caliber that it is, the .270 STW holds 92.5gr of H2O capacity.

So, at 22.5gr of differentiation, there's a huge difference in case capacity and case size. Not to mention one uses a standard bolt face (.270 Ack Imp), and the other uses a magnum bolt face (.270 STW).

 

[FEENIX]

9 and 8 are recommended twist to stabilize the 165 and 175 respectively. Just for quick comparison but a standard 8MM Rem Mag has ~30 gr of H2O over .270 Win. (www.kwk.us/cases.html) .

 

[KyScott]

Lots of good info guys and I appreciate it. I'd still like to hear from somebody running 150s through a 270STW.
Feenix, where is youre zero and what is the drop at 400?

 

[FEENIX]

Lots of good info guys and I appreciate it. I'd still like to hear from somebody running 150s through a 270STW.
Feenix, where is youre zero and what is the drop at 400?

100 yards; 20.79".

 

[KyScott]

10-4 Feenix thanks