Fusion CO2's last chance

[Ribbonstone]

Tried no band, losse band, tight band...same deal, shoots great one session, crappy the next.

It has likely been replaced.  Have had good results with an Mrodair "plinkster", although faster and only running on a single 12gr.  Unless it acts up, that one will be my .177 "sporter" 12gr. co2 and this one will be a "body donor".

[Kailua]

I know you had mentioned as not doing anything between shooting sessions.  But does the barrel get really dirty fast after a cleaning which may affect accuracy?  Of maybe there's cosmoline still left in the grooves or maybe the machining of the lands and grooves need smoothing out.
Was kind of hesitant of posting knowing your knowledge and background with airguns.  If anyone could figure this out I would assume it would be you.    GL

[Ribbonstone]

If I leave it alone (not doing anything, including cleaning) for 3 or 4 sessions, it's likely to go back to shooting great for one of those sessions.

Will try it again tomorrow....just to keep score, after the crown clean up and LDC swap, it shot well...nothing touched....next time out it went back to shooting badly....nothing changed...tomorrow's test could go either way...and the next day a 50/50 shot at good or bad.

Would be a lot easier to diagnose if it just stayed crappy all the time....this on/off behavior just doesn't let you figure out what may be wrong.

[Ribbonstone]

OK...here we go again with the co2 Fusion:



Tested it (with one 12gr) tonight.  Artifical light on target, which still seems to costs me a little bit in accuracy compared to sunlight's brighness, and 5 5-shot groups.

There has been one change from the last outing: a 3rd scope mounted for the 3rd test.

First test:


Second test:


3rd (tonight's) test:


The on/off nature of this ones shooting hasn't been traced down yet. When it's "on" it's quite good for a cheap co2 rifle.  When it's off, I can beat it with a smooth bore Benjamin 340.

Right now it's "on"...tomorrow is anyone's guess (about 50/50 chance it will be as good...or as bad at that 2nd test).

It has been like this for awhile...on/off...old LDC, old crown, new crown, new LDC, 3 scope swaps, up in power, down in power, barrel band, no barrel band, bedded, not bedded, clean barrel, fouled barrel,1 12gr, 2 12gr, lubed pellets, washed.dry pellets, and all points inbetween.

 

[Kailua]

Just a thought.  If I was to scrap this rifle for parts.  I would maybe add two set screws left and right of the receiver too steady the barrel.  From your pics it seems most of the inaccuracies are left to right.  JMO

[DEAN]

Have you tried chronographing it every time you shoot it to see if maybe velocity is fluctuating casing accuracy swings..?

[Jahh]

I have a fusion and have experienced the same thing, but usually during the same shooting session.  I shimmed the rear scope ring so I didn't have to have so much elevation turned into it, and while I think its a good idea I can't say for sure that it fixed the issue.

What I found was that mine did not like anything JSB.  I think they my be too soft.  My groups looked like it was aiming at 2 different points, giving 2 different groups.  Then I switched to H&N FTT 8.64g in 4.51 head size.  The point of impact changed, but after re-zeroing, it literally shooting 1 hole  5 shot groups @ 10 yards.  In fact the first time I shot that kind of group, I though I missed the target altogether, but upon further inspection, yep, 1 hole.

We recently had a 40F drop in ambient temperature, but after re-zeroing the scope it still shot great.

Can you try any of the H&N FTT's?  (preferably in 8.64g at 4.51 head)

[Ribbonstone]

It's been good now for 5 straight tests, so maybe it's cured.   Can't point to any particular thing and say "that did it", could be anything down during take down/cleaning/reassembly.

[moorepower]

A bedding/stock flex issues causes poi shifts. Sometimes easier to shim/ bed than chase. Barrels don't come and go and if velo is close your running out of options.