Canadian Airgun Forum

The black flies were terrible today and there was a frustrating breeze but I managed to shoot enough 30 and 40 yard groups to get some data. I think I can squeeze down the averages a little bit on a dead calm day. I'm hoping for .75" ave @30 yards and 1.25" ave @40yards. I added my 10 and 20 yard data below from a few months ago. On a calm day I will likely try 50 yards and hope for sub-2" averages.

Crosman Optimus 1000 detuned to 770fps with 8.44gr JSB Exact

5-shot groups measured ctc
10 metres - .26, .26, .31, .20, .19, .32, .16, .18, .19, .22 = 0.23” ave ctc
20 yards - .47, .50, .38, .62, .42, .61, .53, .49, .66, .63 = 0.53” ave ctc
30 yards - .59, .64, .70, 1.33, .45, .52, .85, .82, 1.15, 1.26 = 0.83" ave ctc
40 yards - 1.55, 1.18, 1.83, 1.05, 1.80, 1.05, 0.83, 1.86 = 1.39" ave ctc

This rifle has had no custom work done to it. It's all Crosman parts except for a shorter spring spacer for detuning purposes. There was no polishing done inside the compression tube, no piston polishing and no barrel lapping. All I did was a lube tune and tighten up all screws. The cheapo 4X CenterPoint scope was replaced with a 3-9AO Leapers.

That is excellent accuracy for an Optimus. Bravo!

_________________
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Practice is when something works, but you don't know why.
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Two lathes and too many projects

I too am shocked at the accuracy of a virtually unmodified version
I was wondering how it would act if the spring were shimmed back up and JSB 10.34's were used. If you have or ever do please post.

I definitely didn't like the full power with 8.44 grain. The recoil was harsh enough to keep popping the Leapers flip-up scope cap from the rear bell. It only took about a dozen shots to march it off the scope. The heavier 10.34gr would likely tame down the recoil but unfortunately that's not a pellet I keep in stock. I think I have some 10.5gr Crosman Ultras that should respond similarly for recoil. But, I'm not sure I want to mess with something that is shooting so well. The light rifle suits 11FPE quite well. I'll give it some thought.

Cool, and thanks for posting your results b/c we all like to hear ideas and their results which some may want to try
Either way I highly recommend the JSB 10.34. Those and the 8.44 will always be in my stash, and now that I've trimmed my pellet inventory way back those two are probably what I use 98% of the time.
I likely have that same scope and my caps stay put, but they're on there pretty tight, especially with the adjuster ring imprinting into the rubber cap so it's kinda locked on there... I was trying to think of a way to make them stay on better and all I could really think of is making sure they're oil free, or maybe warming it up so the rubber can maybe form to it better? Just some random thoughts...

I did the same thing with my Optimus. I detuned by removing pre-load by cutting up the 3 tiered spacer in the rear and removing 2. I've tried the 10.34 jumbo and while the action is somewhat smoother, it's not nearly as accurate as with the 8.44 exact.

I have a Williams peep on mine and if I'm shooting good I can do right at 1" 5 shot groups at 40 yards.

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