Derrick's Crosman 357

Derrick, our Ohio correspondent, sent in pictures and description of his latest project, a Crosman 357. Enjoy!

The brass "medallion" is a Winchester 357 magnum case head. I bored out the primer pocket hole slightly and drilled out the flash hole completely to run the 6-32 grip bolt though it. Also turned down the dia. of the bolt head to fit. Buffed out the frame. Got rid of all the nasty casting marks.





As you know, the 357 left grip clips to co2 cartridge. In it's stock form, it also does a good impression of the Wiggles. I drilled 2 holes in the frame and 2 matching holes in the grip for pins. One pin is glued into the grip, one is glued into the frame.

Virtually zero play when connected.

I chopped a section off the spare 1760 barrel and reduced the breech to match the stock 357 bbl. I think I turned it down to something like 0.312". It's a nice, tight press fit into the rear of the shroud. I left about 1/4" of bbl at the muzzle at full 7/16" diameter for added heft. Turned down the middle of the bbl just slightly so I didn't have to bore the shroud full length. The ID of the shroud in the bbl channel is just slightly less than 7/16. I didn't bother to measure it, I just took a hundredth off the bbl or so.

Now the bbl can't fit though the "fingers" of the rib sight. Chop. Off they go.

I bored the shroud out to 7/16" rather than reduce the bbl diameter. This is also a zero play press fit to the bbl.

I cut the new bbl approx 1" too long to have material to play with. After reducing 1" or so of the the breech end to 0.312", I cut the pellet lead in. Then I reduced the bbl's middle diameter, then set the cylinder gap. Working forward, I was then able to determine how much--if any--muzzle I wanted coming through the front of the shroud.

So, here's where I left the muzzle. I initially left it extended, but wasn't happy with the look. I cut it, faced it and recessed the crown, cold blued it, then got out the JB Non-Embedding Compound and cleaned the bbl. The 1760 barrel rifling was substantially more pronounced than what was in the flimsy stock 357 bbl.

Here's my cylinder washer to fit over the post. Couldn't find a black one. Didn't want to make one. It's the white washer that comes with Uncle Mike's sling studs. It worked perfectly. Thanks Uncle Mike!

I glued it in place with a dab of Gorilla brand super glue. A little dab'll do ya.

I ended up using epoxy to glue the lead weight into the shroud. I then epoxied the bbl into the shroud in the front and rear press fits. The sight rib is also epoxied (Hey, I had it out) to the shroud.

So, I charged it up and the first shot went dead-ass-nuts through the 10 ring on the 10 meter target. I shot several cylinders through it and I think the groups look about half the size there were with the "floating" stock barrel.

Piston Tuning the Daisy 717

I've long wondered whether the Daisy 717 would benefit from some piston tuning. It's hard to get any useful figures for the performance of the stock pistol, as no pellet weights are given for the published velocity of 360 fps (although Pyramyd says both 360 and "up to 380 fps", and the online manual at Pyramyd says 380 fps). So I put a few 7.9 grain RWS Meisterkugeln pellets through one of my old 717's and found a velocity spread of 368-375 fps. This is with the piston adjusted correctly.

The face of the piston has a noticeable casting sprue, and is hardly flat.

The valve face seems flat.

Putting the piston face against the valve face shows that full contact is not being made.

So I faced off the piston (I took off about .010").

Using some hi-spot blue, I tested the piston face against the valve face. Full contact was still not being made.

So I lapped the valve face against some sandpaper, on a surface plate. The valve hole was filled with a plug of paper towel.

After a few minutes of lapping the face was pretty flat.

As you can see, the faces are making much better contact.
So how much of a velocity gain did this produce?
I found I got between 377 and 380 fps, so a gain of around 5-9 fps. Hardly earth shattering, but nice to know a little performance increase had been realized.

Benjamin 317 "Bar-V" Stock Nut and Washer

A kind person sent me the stock locknut and washer for the Benjamin 317.

The new nut, which appears to be brass, and the lock washer. The washer looks exactly like a standard internal toothed lock washer, or rather it is a standard lock washer.
The nut I made on the left, which looks just a little crude compared to the Benjamin.

The assembly restored to stock condition.

The 1377 Project, Pivot Washers

As I mentioned earlier this week, the 1377 project still isn't completed. The pump arm had too much play in the slot at the pivot pin, so I decided to make some Delrin washers to take up that wiggle.

Drilling some Delrin turned down to 1/2"

Parting off a washer. Each one needed to be .019" thick.

Parting left a burr at the hole which was easily trimmed off with an Xacto knife.

I lined up the washers and inserted the pump arm, at which point everything instantly got misaligned.

So I used a tapered drift to line things up again, and reinserted the pivot pin.
Now the wiggle is gone.

George's Palm Rest and A Friday Ramble

Every Thursday night I head over to my friend Kent' s "open shop" night. It's just a bunch of guys standing around BS-ing, showing off projects and soliciting advice, with cigar smoke and some informal libation...
Anyway, George called me up and told me to bring my Diana 75, as he wanted to show me the palm rest he made for his Anschutz .22 target rifle.

Here's his rest attached to the rail on my Diana 75.

It uses a "split cotter" to clamp the column.

Some detail. I asked him why the tube is at an angle and he said he couldn't remember.
The clamp knob for the handle.

The T nut which fits in the rail.

The molded handgrip.

He said he couldn't remember what product he used, but it was some sort of wood putty.

Anyway, whenever George brings one of his projects by, I'm always temped to just sell all my tools and go off to live in a cave. He really does great work.

In spite of my George induced low self esteem, my unfinished 1377 carbine was chosen as "Mod of the Month" over at airgun artisans. Not sure what to make of that. This blog also received a nice mention in Tom Gaylord's column in the Volume 62, #24 issue of Shotgun News. So fame has been achieved, of a sort, yet fortune seems to not be following. I haven't acquired a new airgun in over a month and I'm going through some serious withdrawals...send me some beaters ASAP!
I really need to figure out how to get some sponsors for the blog.

I was noodling around on the internet and came across this recent Crosman patent for a front sight. Seems like an odd way of dealing with elevation adjustment. Here's an interview with Abhinav Bindra, the Gold Medalist in Air Rifle (an amazing final match!).

Back to the shop...

Front Aperture Sight Inserts for the Hy-Score Mod SM 810 (Diana Model 65)

I finally got around to making some front aperture inserts for my Hy-Score Mod SM 810 (Diana Model 65) rifle. I wrote an article showing how to do this before, but I figured I could show a few details. The insert size is smaller than on my Diana 75, I measured .618" (15.7mm) diameter of the one insert the rifle came with. The insert that came with the rifle has a 3.8mm hole, which is a bit too large for 10M shooting.

I chucked a rod in the 3 jaw chuck to take up the play and bored a small step to hold the insert.

Drilling some holes.

A stack of inserts turned down to size.

Ready for final drilling.

Making the 60 degree cone, I decided to try a steeper angle than I did previously (90 deg.), as I had a chance to look at one on a friend's rifle and it looked closer to 60.

Drilling the hole. I used a combination of metric and number drills to make a range of sizes.

After drilling I used pin gages to determine the actual aperture size. Each insert gets put in a small baggie labelled with the diameter.

A Crosman 101 Quandary

Regular readers will remember that I bought the Crosman 120 and a 101 in pieces, knowing that the 101 would be missing some parts. The first question to be answered with the 101 is "what parts?"

Yet another valve wrench gets made.

The finished wrench. I think I now have enough wrench variations to take apart any Crosman I come across!

The valve removed from the action.

So, having disassembled the valve, I now know what parts are missing. I referenced the service manual and checked the parts I have against the exploded drawings. I am missing the entire hammer assembly, and the entire bolt assembly, as well as the rear sight. I bought DT Fletcher's CD of the engineering drawings for the 101 and I can, in theory, make the missing parts. However making the Hammer Sleeve (PN 101-39) is somewhat complex.

It has a 5/8"-24 tpi. internal thread (and the hammer plug has a matching external thread) which is not a standard, nor do I have taps & dies, so it would have to be single point threaded on the lathe. That alone isn't much of a problem, only somewhat time consuming. However the Hammer Sleeve is also the sear, and as such is called out as "Cyanide H'dn", which means I'll have to dig out the Kasenit and do a case hardening to the part after machining. Again, not that difficult by itself. Add to that the need to bore 2.25" deep a flat bottomed 37/64 hole, w/ 1/64" 45 deg. chamfered corners through the sleeve.

So, the part is relatively time consuming to make, at least compared to the other parts, on a rifle that even in good condition isn't worth much more than $100-$125 given its vintage (It's a later model).

So, should I try and find some parts to complete the rifle or should I make the parts myself?
I just don't know. I'll think on it for a while.