Varibles in isolation (SPA 600W/"Varminter" post)

[Ribbonstone]

MrodAir co2 "plinkster" or SPA 600W rifle..same critter, just different importers)...keeing changes in isoltion.

NEVER a good idea to embark on a mission without a clear objective.  Mine was to get this co2 rifle shooting at about 8 foot pound for 40 shots (total of 320 foot pounds of energy per 12gr)...BUT, wanted "good" shots inside orf 4 or 5%. of the single max reccorded shot. 

NO interrest in the shots that keep dribbling out the barrel at ever decreasing speed, which happens when co2 starts to run in it's "only gas" form (while ther is liquid co2, the varation is quite tight). Really don't know what the total energy per 12gr. would be if I kept shooting until I had to rod-drive the last stuck pellet out of the bore (and really don't care to find out)...if it's not "close" in speed, who gives a rat'sarase?






As show, with the loaded mag, full sized 4X32mm scope, and 3 full 12gr. in the tube, runs right at 6 pound even.

Set the rifle back to close to factory tune specs. Not uite, as the striker spring guid had been shortened a bit, but the rest of it wwas as close to "out-the-box" as possible.


Shot one 12gr. over a chronograaph at near factory specs.


Took it apart and shanged just the striker weight.  Striker sping tension, spring guid, transfer port, etc., were the same, only the weight of the striker was changed.

Turnes out the issue striker comes in at 35 grams.  I wanted to go for a 20% reduction in weight (to 28 grams) but I slightly over-shot that and eneded up at 27.5grams.  NONE of the tube-bearing surfaces where changed, the sear is the same, as is the lenght of the striker.

Comparison shot string:


I'm not "there" yet.  HAve about 1/2 foot pounds X 35 shots to trade for another 5 shots...which would be easily "do-able" to reach 40 8-ish foot pound shots per 12gr.





SOooo..the end result of about a 20% in striker weight, no other changes, seems to be a 13fps reduction in velocity, a 4/10ths reduction in energy, and an 11 shot increase (about 46% more shots).


Seems like a great trade off to me.

Add to that, that the rifle got noticeably quieter (even with that small sized LDC attached).  Just using less co2 per shot, which is less volume for the LDC to deal with, which is why the little-bitty LDC works so well.

3rd 12gr. used for test targets at 20 yards.  Did "waste" the first 5 shots getting the scope re-set for zero (after having it apart to get to the striker, putting it back together, did you really expect it to return to "right on" zero?).





NOPE..it ain't a match rifle.

Does seem to be accurate enough to shoot as far as I'd use an 8-8.5 foot pound .177 in anger.