This is a continuation of the "Reduced Load Test", spawned from an idea I had when discussing reduced loads for CMP Garand matches. The rules say the gas system has to be functional and the ammo has be safe, but it doesn't clarify if it has to cycle the action.
Edit 10-22-16: CMP Service Rifle Rules state "Must be designed or modified so that only semi-automatic fire is possible". Meant to apply to M16s or those with DIAS type parts, but I can see it applying to a "bolt action".
Plus I like the sound of UK legal ARs.
For easier/smoother cycling, I removed the charging handle latch and had to grind the top of my forward assist a little so my index fingernail wouldn't catch. (still chipped my middle one though, dunno how)
Load:




- 50gr VMAX bullet




- 4.5gr Red Dot powder




- CCI 400 primer




- FC case




- 2.255" COAL
Avg. Velocity - 1488fps


Extreme Spread - 54.3fps


Std. Dev. - 17.6fps
This is just enough gas to push the bolt carrier back a wee bit with a worn rifle buffer system.




There seems to be some powder position sensitivity as evidenced by occasional tumbling (transonic?), so a hotter primer or more powder may be better.
A slickside, sidecharged upper would be superior in this application as evidenced by our friends across the pond.

Timestamps:

0:00 - Sighters

7:22 - Offhand

16:44  - Prep for Sitting Rapid

19:02 - Sitting Rapid Fire

20:50 - Prone Rapid Fire

22:27 - 1st string Prone Slow Fire

29:32 - 1st Prone Slow result

29:39 - 2nd string Prone Slow Fire

33:38 - 2nd Prone Slow results



After rereading C.E. Harris' "The Load" (http://castbulletassoc.org/forum/view...),
I realized I was being a little too careful last month, and heeded the
advice of using a "normal" weight/length bullet for the cartridge.



"The Load"

Bullet - 168gr Hornady BTHP

Powder - 13gr Red Dot

Primer - Winchester Large (not preferred)

Case - match-prepped PPU

COAL - 3.300"



There's
still a little powder position sensitivity it seems, as well as a
slight wobble based on some barely oblong holes (maybe same issue as the
50gr VMAXs?), but this is a viable load for 100yds.



For anyone
who wants to try this - keep your cheekweld. Lifting my head between
shots in rapid fire is a bad habit from working with standard bolt
actions. Also, if you're a bigger guy like me, increase the length of
pull.

Quoted:


It's not legal to have the rifle in your shoulder prior to the targets coming up out of the pits in rapids.

Quoted:


So basically remove your gas tube and plug the block? Looks like it would be fun to try, but i dont want to tear apart my rifle

*Never trust your scorer. Look at your target before signing the scorecard, don't glance. While making this video, I realized I got jipped 7 points and an X.

This may be my last experiment for a while.

Timestamps:
0:00 Offhand prep
0:27 Offhand
8:06 Offhand result
8:11 Sitting prep
8:48 Sitting
10:55 Sitting result
11:00 Prone Rapid prep
11:23 Prone Rapid
13:02 Prone Rapid result
13:07 Prone Slow 1
13:12 Prone Slow 2
13:16 Summary target
13:20 Overall scores

Load data:
- 50gr VMAX
- 5.0gr Red Dot
- Winchester SR
- FC case
- OAL 2.255"

Chrono data from September of 2016:
- Avg MV: 1571fps
- ES: 60fps
- SD: 23fps