Just wanted to pass along some info after getting my feet wet with my 6.5 STW .
This rifle has a 3 grove 1-9 twist Pac Nor finished at 28 inches.
I started into this project hoping like everyone else to hit 3400 fps with a 140
class bullet. I had 140 amax, 130 scirocco , 140 smk and 142smk to try out...In
hopes of squeezing the most accuracy/speed out of this class/ weight of bullet.
I started with the 140 amax hoping to find a good load to use on LR coyotes
around the ranch. I worked my way up to 86.6 of wc-870 at a vol. of 3385. It
shot 1/2" groups and I tested out to 500 yrs on rocks with great results.
I then got curious and decided to see what other combos it would shoot well.
Tried - Retumbo, Ramshot mag, RL-33 in addition to Wc-870 & 872
It shot the 130 scirocco's at a max load of 81.2 grs of RL-33. They shot at an
avg. of 3470 fps into the .7 range. This load was around 70 to 80 fps faster
than I could initially reach with Retumbo or Ramshot mag in this rifle before
seeing pressure signs. This bullet like others have found was little slower in regards to vol. than I had hopped for.
At this point I had around 150 rds through this rifle.
I decided to take my old 140 amax load out for a stretch ...It would
consistently put three shots 3/4" apart at 200yds, but then it started throwing the
3rd or 4th shot 2" out of the group... ?
I then shot a group after allowing the barrel to cool completely after each
shot...it shot without incident, no 2" flyers!
So.... I believe that with a little extra heat from the shot string and my
increasingly rougher throat, that I started to see issues with the amax at my
speed of 3385 with my 3 grove 1-9 twist barrel at around 150 rds. Anyone else run into this with
the 6.5 amax's at this speed? I steered clear of 140 vld because of not wanting to wast time
and barrel life on a bullet that would not hold up at extreme speed/pressure but
may have run into the same issue anyways.
I knew that my combination was prone to this type of issue, 3 grove/thin jacket/
high vol. but did not realize that Amax's may also have been prone.
I then ran 3 rds of tubs Final Finish throat maintenance before trying to
perfect my next load.
I loaded up a few 140 smk that I had on hand... Worked up to 86.2 gr of wc-870
... shot 3rds at my 450 yard target....3" group....hum.... Some promise.
Set up the CED Chronograph and shot 3 rounds loaded at 86gr. of 3400fps into a
tiny little hole at 100yds.
Stepped out to 350 yds and printed a 1.3" group with a it's max load of 86.8 grs
I backed it back down to 86.0 gr. of wc-870 to save on brass. This load produced
a 10 shot ES of 19 fps.. Which was as low as any other powder I tried in this
Other loads tried so far..worked up to max
86.2 gr wc-870- ave 3415 fps
86.8 gr.* Max load 3440 - 1.3" group@ 350yds
86 gr. wc-870 ave 3400- .352 group!!! (continues to shoot well, my working load)
130 scirocco ii
79 gr ramshot mag- 3375 fps
*Max load- slight pressure
79.5 remtumbo- 3344
88.2 gr wc-870 - 3350
Rl-33 81.2- 3460
I'm hoping to start testing the barns 127 LXR Shortly in order to find a Good
non lead load for our lead free zones here in CA.
And waiting on some of the matrix 6.5's
The Testing platform