Canadian Airgun Forum

Huge cardboard box came today full of B18/19 plinkers.
My quest? to own a non-PAL wood stock NP .22 cal rifle.
Not many of those around so I have to build one, either with NP parts put into a wire springer or...
a hybrid, so here's what I got.
1. Crosman Optimus, .177 cal, wire spring - short piston a bit beat up - so will refinish the stock, it looks nice has good grain and character.
2. Crosman Shockwave .22 cal - NP - long piston, shoots butter smooth

They will be hybridized, becoming a Shocktimus and a Optiwave (just swapping stocks). I have no use for
.177 cal so the Optiwave will be available after I tune it sweet. I have all sorts of goodies just waiting to put in to both guns, can't wait!

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Iacio, ergo sum

I just tuned my own Optimus (with a weak steel coil spring though), curious to see what you'll end up with . What's on your list of mods?

One mod I did to my TR77NPS was to add a plastic ''wear shoe'' on the piston end of the cocking arm, as the end of the arm scrapped on the gas ram at the end of the cocking stroke. May not be an issue on your gun though .

Another mod I did was to add a nylon bushing on the gas ram's end, to help stabilize it into the piston. Here's a link to the installation instructions for the kit Charlie Da Tuna sold a few years ago, in the last pic you see the bushing installed: https://www.airguntoys.com/NP-GRS_files ... tPage1.htm

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If everything's so lovely yeah, then why don't I, why don't I, why don't I, why don't I feel lovely?

Hi airmec, first I have to pull them down and physically see what is going on inside. First step is to chrony them to see their speed as-received.
Mods planned for the Shocktimus: 1. ETA trigger mod, brass breach washers, stock swap, muzzle break, inspect and polish/deburr internals, go from there.
For the Optiwave, all that a plus piston liner. Right now, the breach lockup is great on both rifles so I'm please with that. The early models often had weak alive jam spring and lockup was hit and miss.
I've had and tuned about 10 of these in various forms from Quest/Phantom/Trail/Venom/Optimus days so I have lots of experience. Since I'm going for smoothness not power all the "centering" and vibration reducing mods will be investigated for sure. More to come as this unfolds.

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Iacio, ergo sum

Those B18/19 rifles are my favourites. I've got four in .177cal in various forms. The indoor tuned version shoots 7.9gr at just over 600fps. It's got the 170mm piston and weak Crosman 4B mainpspring (600fps spring). I've been tinkering with other airguns so hadn't shot this rifle in months. I dusted it off a couple of days ago and shot one group from the rest at 10 metres. One fouler shot into the backstop followed by 5 pellets into a small target. Pleasing.

I'm looking forward to reading about your non-PAL .22 NP B18 Shocktimus.

Nice! I hope I can achieve results like that!

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Iacio, ergo sum

Well stocks swapped, and I tore into the Optimus. Someone has been in there before, she 'aint no virgin that's for sure. Optimus piston and spring shown above. It had a long piston, now chopped, internals polished quite well, piston seal good condition. Vibrates like a cattle trap and twangs like a tourist - I'll run it over the Chrony before starting a tune. I didn't do that yet because I have my chrony set up far from my trap and don't want to "miss" and put holes in the drywall. The Shockwave is like new from box, never opened or messed with, looks clean as a whistle - shoots so smooth i don't want to open it, but maybe after I run it over the Chrony I will. Here thery are now, Optiwave on top, Shocktimus on the bottom.

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Iacio, ergo sum

How long is the chopped piston? It looks a bit longer than the full-power 150mm length.

I didn't measure, and now reassembled so i can run it over the Chrony. But it couldn't be much shorter because the sear hole is pretty near the cocking slot. I believe the cocking slot is std size for all pistons.

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Iacio, ergo sum

Hi Duke,
I got one of the charger, I replaced the stock too with a cometa walnut stock, have to modify the inletting a little bit and it fits perfect, I agree with you that the shockwave shoots very smooth, so it deserves a good stock so I look for a nice stock, too bad the stock with the height adjustment cheek piece was sold so I decided to get what's left, upgraded the trigger with a nylon thick bushing and it was good. here it is

Pistolero, that looks awesome! I now remember you posted about refitting a Cometa stock, I didn't think about doing that, and with my newfound stocking skills it should be a easy job for me. Anyhow, I'll pretty up my Optimus stock with some nice finish, add a white line butt pad, maybe some fanciness under the pistol grip area too. Hey, maybe time for me to start checkering! My good friend R-Gun Pete got me interested in checkering a long time ago, but I was too timid to try it.

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Iacio, ergo sum

I set up the .22 cal Shocktimus with scope and did some quick sighting in and ran a bunch over the chrony!

I am thoroughly impressed! I ran the last of a tin of JSB Express RS through and it was doing 458 fps with ES of 4 fps! Pretty much what I'd expect for a factory detuned Crosman for speed, but the ES is impressive. And look at the 10 shot group, 10 yds, scope set at 12x. That's just awesome... to tear in or not... couldn't harm it I don't think - shot cycle is smooth as butter and quiet as a mouse.

The Optivwave .177 is another matter.. very twangy, and I only shot it over the Chronyvwith open sights... got them all into the trap. But... it's shooting hot with Crosman HP 7.9 gr at 570 with ES of 20. Smoothing and de tuning will be necessary. The spring in it has about 2" preload so a coil or 2 off will help. Also, I have amassed a pile of springs, maybe just a spring swap needed. With the plastic stock and open sights it's light as a feather.

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Iacio, ergo sum

Nice shooting with the Shocktimus. Tackdriver!

You could likely detune the Optiwave by reducing the spacer length. I don't think any of my B18 springers have the thick OEM spacer. I have gone so short that the end plug only requires 3/8" push with the thumb to insert the crosspin. Almost no preload and accuracy was fine. A simple piston liner gets rid of the twang.

Aye, good idea to just machine a new end spacer (its removable, green circled below). I'll have access to the machine shop again after "reading week" @ end of Feb. And I have been saving a nice aluminum shaving cream tube for just such eventualities; i.e., piston liner!

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Iacio, ergo sum

You can use a washer stack for spacers. Have a look at Home Depot for some 1/2" washers that are the right OD.

For a piston liner I often use large yogurt or cottage cheese containers. The thickness is usually perfect for the B18. The plastic is slick.

Gottit. I have an idea to make a video with good audio to showcase the difference between twangy untuned and tuned version of same rifle. Did you ever experiment with shimming a NP, like the shockwave, any power increase? I played with NP conversions 8-10 years ago but my memory is so bad I forget what I did and what the results were. I actually have a pile of NP in my tool chest left over from those days. Couple years ago I sold off all by B18/19 parts because i swore off of them... here I am again back into 18/19s. I did the same thing with QB78/79 sold them all and now have bought them all back again..

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Iacio, ergo sum