308 subsonic Experiment #8

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Artful
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308 subsonic Experiment #8

Post by Artful »

Test date 8/21/07 time 8:00 am to 10:30 am
Temp 98-103 Humidity 36%
Sunny and clear Wind 4 knots
Far East Valley out of Phoenix AZ

Cases filled to bottom of neck with Plastic clay and baked at 300 degrees for 20 min to solidify.

Flash hole diameter drilled at 1/8”, 3/16” up from rim.

Powder cavity diameter drilled at 3/16”,
drilled down from neck to need extended flash hole.
Remington 150gr Bullet PSP - moly coated
Each case loaded with 3 gr of Red Dot

(this loaded filled the cavity 7/8” up from bottom of case. filling the case to the bottom of the neck holds 5.7gr of Red Dot with bullet seated you have room for 4.7 grains of Red Dot)

Case—Remington with primer hole drilled out.

Each of 7 rounds weighed in grains loaded, velocity in FPS, FAL with or without can, overall length

#-Weight..Feet Per second...Suppressed....OAL

1-372.4....486.6...................yes................2.705

2-374.0...605.1....................no.................2.700

3-372.6...525.8...................yes................2.700

4-370.8...438.6...................no..................2.700

5-374.1...573.2...................no..................2.702

6-371.6...372.1..................no...................2.699

7-374.0...511.3..................no...................2.695

Needless to say I'll be upping the charge to see if it improves the consistancy of velocity and trying to get closer to 1000 fps.
Last edited by Artful on Thu Aug 23, 2007 11:59 pm, edited 1 time in total.
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yondering
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Post by yondering »

Just a question, why are your seating depths not the same for all 7 rounds? You have a variation of .010" in OAL, this will affect both velocity and accuracy. If you are trying to achieve consistent velocity, seating depth should be consistent.

I'm interested to see how it works out for you.
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Artful
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Post by Artful »

I think it has to do with the crimping process as the seating die is set the same but before shooting it was checked and noted as you see.
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Selectedmarksman
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Post by Selectedmarksman »

The question will make it obvious I'm new to learning about reloading, but... you crimp a subsonic load? I thought you weren't supposed to.
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Artful
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Post by Artful »

I do a slilght crimp - that's do to feeding from magazine in the FAL - I don't want bullet setback which would increase pressure and speed.
"Trying to tax yourself into prosperity is like standing in a bucket and trying to pick yourself up by the handle." - Winston Churchill
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