Monday, March 8, 2010

Minimal Grip Fitting for my Tempest

Probably the last time I shot the Tempest was during the trigger job. I bought most of a set of target grips off Ebay (cheap) for this gun and never got around to making the missing palm shelf.

Not that the shelf would be all that difficult to make--it's just a host of things. The target grips are warped and are very poorly fitted. The grips are made from bolong-eta and trying to find a piece of matching wood is rather difficult. I bought some Gaboon ebony, but it's not quite right. The color is close, but ehhhhhhhh...it might pass the 5 foot test.



The grip halves don't fit at all on the front strap. I'm sure I could make them fit, I'm just not that excited. These are really just too much grip on the Tempest and this isn't a target gun anyway. I sent Nick a Webley Hurricane over a year ago with a complete set of match grips and I think they better fit that larger framed gun. Of course, Hurricane's aren't target guns either but they look more proportional.

So I sourced some of these finger-grooved Tempest grips. I think Beeman used to call them "combat" grips. Yeah. Lookout. They're supposed to install with a super long M3 x .5mm bolt that goes through the center bushing and tightens into a small threaded bushing that is press fit into the left grip panel. The M3 bolt was too short to engage the threaded bushing and it was pretty wimpy anyway. I elected to use M4 x .7mm socket head cap screws and thread directly into the center bushing--just like the stock plastic grips.

The counterbores are too small in the grips for the M4 cap screw heads. Used a forstner bit to open the left side up.

While the left grip fit perfectly, the right side wouldn't sit flush on the grip frame. The grips have circular wooden protrusions that mate into round recesses in the frame.

What a stupid tough way to make the grips. Here are the recesses.

Pressing the grips into the frame left shiny marks on the high spots. Used a curved carving tool to take off some material.

Test fit. Grip still isn't quite flat on the grip frame.

Another view.

Remove a fraction, test fit, repeat.

Finally flat.

The screw cup for the M3 has to come out. (By the way, the threaded fitting in the left grip panel fell right out.)

Couldn't get behind it and it's really in there tight. I hit on the idea of tapping threads into the bottom of the cup. A #8-32 was a perfect fit.

Screwed in an #8-32 bolt.

A small punch then drives the bolt and cup out.

Went very slowly and deliberately so as to not split out the wood.

Ahh--it's knurled--no wonder it was in there so tight.

The right side grip didn't quite line up with the threaded center bushing. I adjusted the through hole slightly then counter sunk for the bolt head.

I just counterbored to the bottom of the existing hole. I think the bolt is too far below the surface of the grip. This hole is very slightly ovalized to line up the grip screw with the center bushing. If the head of the bolt is closer to the surface it'll better hide the oval shaped hole.

The left side grip screw is also recessed, but not quite as deep. I'll raise this side as well and try to make them match in height.

Found an extra M4 cap screw and a bunch of small brass washers.

The washers followed with two nuts to hold everything in place. Chucked into the Taig lathe and shaved the brass washers down until they were the same diameter as the head of the M4 bolt. Easy, didn't measure a thing.

Used a carriage stop so I wouldn't run the knife into the jaws.

Wasn't gonna try for that last washer. That's jaw protection.

Spacers finished.

Done. Needed three spacers under the right side grip screw and one under the left.

Looks OK from this angle.

Not bad on the front strap either.

Just a few really small ridges where the grips come together.

It's not worth it right now, but the next time I have a small sanding drum out for another project, I'll make this seam go away.

Saturday, March 6, 2010

BSF S20 WCM Pistol

Derrick forced me to buy this pistol.

New in the box.

Even newer.

Came with a brush, a tiny tin of pellets. It's "select".

The end of the box.

Looks good.

The grips are comfortable.

Yet another pic.

The sight. Fine adjustment for elevation but coarse for windage.

The BSF logo.

"Made in Germany West".

So you know it's German.

Leather breech seal.

There's a lot on this pistol out there already:
http://www.pyramydair.com/blog/2008/09/bsf-s20-match-part-1-germanys-rifle.html
http://www.pyramydair.com/blog/2008/09/bsf-s20-match-part-2-germanys-rifle.html
http://www.pyramydair.com/blog/2008/09/bsf-s20-match-part-3-germanys-rifle.html
http://www.muzzle.de/N3/Druckluft/BSF_S_20/bsf_s_20.html
http://www.gunspares.co.uk/shopdisplayproducts.asp?id=24802&cat=BSF+S20+MATCH

Let's just say it's a pleasure to shoot.

Friday, March 5, 2010

A New 2250 Gas Tube

I sort of accumulate parts for airguns. Occasionally, I'll look at the pile and realize I'm but a few pieces away from being able to build a new gun--usually a Crosman 22XX. This time, the key part needed was the gas tube.

A new Crosman 2250 tube--part number #2250-009. Problem was, my steel breech has the "new" breech screw location at the rear of the bolt trough. Actually, that's not the problem--the problem is, though the new gas tube is drilled for both the old and new breech screw locations, only the front hole was tapped with 4-48 threads.

Looked through all my bajillion taps and seems I didn't have a 4-48. Need a 7/32-40? How about a 2-56? Unbelievable. Hit Kromhard's this morning and sourced a plug tap for under $4.

I was mainly concerned with alignment of the threads to get them perpendicular to the tube. With such a thin wall to thread, it would be very easy to cut the threads at an angle. I wondered about just using the existing 4-48 threads that Crosman did cut to align the tube.

With rubber jaws installed in the vise, I gently grabbed the gas tube. Threaded the tap into the existing forward screw location, then brought the drill press table upward until I could chuck the tap. Since the gas tube was held loosely, the tube rotated in the padded vise jaws until the tap was vertical. Snugged down the gas tube, left the tap in the chuck, and centered up on the threadless hole.

Turned the chuck by hand and applied a bit of downward pressure to feed the tap into the hole.

Finished by hand. It's more than accurate enough for the application. Still dragging my feet on the build. Leaning towards .20 cal but waffling on barrel length. I'll need to make a few parts, too, in the coming week. More soon.

Thursday, March 4, 2010

Aperture Retrofit for the QB77

The Crosman 411 aperture sight was a nice addition to the QB77, but I wanted a larger diameter disc. The 411 disc is also too small in diameter to fit a rubber eye cup.



I was ready to make a new disc when I remembered that I had a spare aperture for a 10-meter match rifle.

I think it's an old Anschutz.

Size comparison. The Anschutz (?) has a weird M9.5 x 1mm thread. Then again, the Crosman 411 has a weird #12-28 thread...

After looking at the aperture for a while and making some comparisons to the 411 sight base, it looked like a fairly easy retrofit. Chucked the aperture into the 3-jaw to begin.

The ID of the threaded tube was exactly the right size to tap 1/4-28. Started with a plug type tap.

Followed with a bottoming tap.

Finished by hand with a proper tap handle.

A scrap of 0.250" drill rod about an inch long.

Faced both ends.

Turned one end down to approx. 0.212" or thereabouts.

Flipped the rod in the jaws and threaded the larger .250" diameter to 1/4-28.

Turned the rod around again and tapped the smaller diameter to #12-28.

Spotted.

And through drilled with a #29 bit.

Cut a small relief at the base of the #12-28 thread.

Scrounged a washer/bushing/spacer from a parts bin.

And bored out the ID to just fit over the exterior threads on the aperture.

It's strictly a cosmetic touch to cover the unused exterior threads.

Removed the elevation and windage plate from the sight base to test fit.

Greased the double threaded adapter and snugged it down into the aperture. Pulled the rubber eye cup off the HW 35E.

Anschutz (?) installed.

Looks exactly like what I was after.

Since I didn't damage or modify the exterior threads, the Anschutz disc can be still used on the correct base as well.

I'd still like to refinish the stock, get rid of the knurled nut with a recessed fitting , add a rear sling swivel stud, overhaul the rifle... All in good time.