Seal mk13

[CMaier]

After my dismal failure with a new 300 wsm from remington, i went back and looked at other options.
I settled on building a rifle similar to the mk13 300 wm that the SEALS have used, and to use a copy
of the new mil 220 gr 300 wm load. That load uses 68100 psi for an max operating pressure, a plus p rifle load.
I was able to get a correct profile Lija bbl, a Stiller Tac 300 action, with mag and bottom metal with a 20 moa
rail. a Mcmillian a5 stock, Night Force 5.5-22x56 scope and a Timney 700 trigger. PTG makes a reamer for this
rifle/ammo combination and i ordered one of those. The plan is to be able to hit large targets out to 1500 yards.
The mil considers the 300 wm with this load a 1500 yd rifle, up from 1200 yds with the older 190 gr load.
The Stiller action has been used for a while on some version of the rifle. An a2 stock was used for a while.
The SEALs jumped to an Accuracy International rifle in a kit. the mk 13 is on version 7 and 8 right now.

 

[CMaier]

the reamer showed up last night...yes 7:45 in the evening....13 hours on s ups truck, 12 miles to my house.
chamber reamed, threading to do.

 

[CMaier]

Mock up
I have tactical rings and a trigger to install,
after bedding,
thread and install suppressor,
and think i will melonite/ sbn the bbl.

and the stock is grey..not purple,,strange pic.

 

[John S]

Hope you have a good spotter.

 

[CMaier]

I recently met a guy that does long range steel matches,
out to 2000 yds. I think i will zero at 800, should be able to do
1600 'easily"(lol) and hope to make some longer hits.
They use spotters for score and feedback.

 

[CMaier]

Did a shoot one and clean while looking at powder increments.
I did 9 one grain steps of h100 up to 81 grs.
I got better than expected velocity and stopped at 7, did not shoot 8/9.
Shots 4/5/6/7 went in to one hole at about 1/2" at 100 yds,
not bad for one grain steps. The rifle may have some potential.
Still waiting on the suppressor and mount.

 

[CMaier]

shot 3-3 shot groups today.
76 gr shot 1.3 but 2 in one hole
77 gr shot .646
78 was a pattern not a group
all at 200 yds.
next up is to thread and fit the brake and suppressor

and then fine tune loads before shipping it
out for melonite on the bbl and lug.

 

[CMaier]

update
i have over 40 rounds thru the rifle.
the milspec for the mk248 mod 1 ammo
is just over 1 moa at 600 yards, and 4.5 at 300.
i am at .66 for 200 so think i am good.
here is a 99% pic:

 

[CMaier]

the bbl has not been melonited,
that is black tape..just for the pic.

 

[CMaier]

final config

with the bbl melonited

 

[CMaier]

today i shot the rifle for the first time since getting the
bbl melonited/salt bath nitrating.
10 shots to check accuracy,and velocity.
while accuracy appears the same, velocity
was up 25 fps in spite of cooler day. 55-60 today.
i also shot rl-26. to give a bench mark for my current load
i am just over 2900 fps with a bit of a bolt lift stick at the top.
the rl 26 went to 3047 before an even slight stick at the top.
i need to go back and do accuracy testing, but it would appear
the goal of 2900 is easy and 3000 maybe doable with good case life.

 

[CMaier]

three 3 shot groups with rl26.
.288 at just under 3000 fps
.435 right at 3000 fps
and .288 again just over 3000fps.
no issue with bolt lift. no high pressure
marks on case.
need to go try at 500 plus yards.

we actually shoot single shots with a back up
if we miss, so three shots is a good indicator.

 

[CMaier]

i had been using a single 1 lb bottle of reloader 26,
and after a very intense search was able to locate 2 8 lb
jugs from one lot..but it is a bit slower so back to load work up.

i currently have a load right at 3000 fps that is shooting .32 at 100.
going to re shoot at "on the lands", +.005, and -.005 to see if there
is a change for the good. switched to nosler brass.