250Z Hard data, .25 .250z

[PestPlasteringPlinker]

Stock 250z.

Remove horizontal pin under bolt action,

Remove both internal hammer spring lug, and external hammer spring lug.

Install RA slug kit.

Wrap Teflon tape around external h.s. lug.

Flush it up with block. Tune internal hammer spring at 2600 psi for Apollo 33 grains on a polished barrel.

Super accurate at 920, I did have to bump regulator to 2750, and tune for grouping, not power

UPDATE!

Opened valve, and thimble to 3/16".

Thimble, slightly over, (I can't remember which decimal point the bit was, literally just shy, of the rings, external)

Thimble, for those that don't know, is the brass piece that the pellet/slug slides into, when you push the bolt forward.

Polished internals after opening thimble, and valve to remove burrs.

Polished, and lapped new barrel for .250 caliber to .2508 after slugged. No chatter, smoothed throughout.

2600psi hammer spring in same placement as with Apollo 33 grains, max(average) with fine tune stock light polished barrel, 880.

New barrel, opened internals, and a 33.49 jsb knockout at .251, average 900. Deviation, less than 4.

I will be running targets tomorrow at 40 yards(give or take 1) and adjust hammer spring for best grouping, and adjust regulator in increments of 100, and re tune.

Amazing improvement after opening and polishing internals.

 

[PestPlasteringPlinker]

UPDATED NUMBERS.

2750 reg pressure, jsb ko, 33 grainers, grouping 1/2 inch(minus my twitches) pretty consistently.

915 fps gave me the most consistent accuracy and lowest deviation on these. 3 ft pound swing. 912-918, 8 out of 12 slugs ran at 915.

Same reg pressure, readjusted hammer spring, and tuned in on h&n 2505 32 grainers.

3 shots before I was off the reg, and after that, i was way too jittery to repeat.

50 yards less than 1/4" ctc. I truthfully thought maybe, maybe I was getting reg drop, or flyers, because it looked like one hole. Walking out into the field to retrieve the target, nope, you could see just barely a stacked out triangle. So close, it literally looked like one hole.

My chronograph picked up one of the 3 shots at 937, the other two, mystery. but spring sound, and report sounded identical. I know it sounds weird, but it has a sound to it, when its over sprung, or undersprung, or too much air makes it out the mod. I think, I might back off the h.s. by 1/4 turn, at most, start with 1/8 turn. But boy howdy, am I honestly impressed. And the authority they hit with from 50, the cow scratching brush, was throwing off fiberglass powder with every smack.