315 FPE – HomeBuilt AirGun – Testing & Tuneing

I have been testing and tuning on my 9MM Home built air gun.
Bored out the valve until it will just open at 3100 PSI.
It used to open just fine at 3600 PSI.

Now it will push a 150 grain .357 slug @ 973 FPS with 3000 PSI
That gives 315 FPE !!!
It still gets 892 FPS for 265 FPE @ 2000 PSI
The 48 Cubic inch tank gives 8 or 9 shots

The .357 slugs are soft cast and sized to .352″.

Check out my new chrono setup.
Its designed to prevent chrono damage.
The gun is held by two delrun plastic clamps.
It has two lightbulbs for illumination and the top hinges open,
There is a spot to pile up wood to stop the pellets / slugs.
It has a 1/4 inch thick, aluminum, ultimate backstop.

Check out the 150 grain slug that hit the aluminum backstop.
It is well mushroomed!!!!

I have a new 26 inch barrel ordered for the next gun.
It will give me another 9 inches of barrel.
Maybe i can get the new gun up to 1100 FPS for 400 FPE???

Mark