Thursday, January 22, 2009

Derrick Lightens His Webley Tempest Trigger

A few weeks ago, I bought a .177 cal Webley Tempest pistol from world-renowned airgunner, Wayne Burns. Thanks Wayne! When I shot the gun, I thought the trigger pull was in the 12+ pound range. (Not Wayne's fault!) It was like a Glock with the "New York" trigger. When I told Nick how high it was, he said I must have the target model! Both Webley Tempest and the similar Hurricane air pistols (same base guns, different sights) share the same trigger mechanism. Until recently, I'd owned a Hurricane for about two decades and that trigger was just as heavy.

Nick and I pondered the trigger situation. Then, Nick forwarded this link:
Seems like I'm not the only one who thinks the trigger pull weight is absurdly high.

The trigger is retained with, yep, small roll pins. What a great way to start! More required reading: Nick disassembled a Webley Hurricane on a previous blog post. Pay attention to the way he numbered the roll pins for disassembly. Handy!
Note: Worry not. There is exactly zero danger that the mainspring will come blasting out of the gun by removing the roll pins.

Grip panels off. Unscrew the flathead holding the safety lever and pull it off the stud. The safety spring then comes right off.

Knock out the roll pins in the order Nick has them marked in blog post #31. Not necessary in the least to push them completely out of the frame. I pushed them out from left side to right.

The trigger and sear are buffed (bench grinder fitted with a 6" stitched wheel). Lots of polishing compound on the wheel. A small container of water near the buffing wheel keeps the part cool. All the mating faces are polished until they look like mirrors.

Trigger and sear after buffing. The allen set screw behind the trigger blade gives the spring something to bear against. Screwing it in increases trigger pull weight. Backing it out lowers. The trigger spring is so stiff (and so long) that the set screw only really gives you the option of "too high" and "really too high" in it's adjustment range. The spring is 0.145" diameter and 0.616" long--"free length" in spring speak.

The trigger shoe is from Crosman It's for their 2300 custom shop guns. It fits quite well. Crosman part number 2300-012. About $9 if I recall. It's not always available for after market sale. Beeman used to sell a really nice steel trigger shoe from Flaig Ace. Beeman's old part number was #7761.

I looked around at all my springs, but couldn't find anything small enough in diameter to replace the stock trigger spring. A trip to several local hardware stores also came up dry. It's possible that Webley used a metric sized spring. If that's the case, it's probably a 3.75mm OD and it crushed very, very slightly when I put a caliper on it. I found several good options in a few seconds online, but didn't want to order and wait. I chose instead to cut 2 coils off the spring to lower the preload. Alternately, it might have also been possible to change to a shorter set screw in the trigger itself that bears against the spring. Either way, the spring will then exert less force against the sear.

Pick your poison. Just cut the spring shorter. Reassemble in the reverse order. I lubricated all the contact surfaces with Castrol MP grease. Use whatever bearing/chassis grease you have around. And, yes, a moly grease is fine for this as well.

The return spring for the sear goes in this way. This is the only part that might cause some head scratching during reassembly.

There's a relief cut on the trigger guard for the long leg of the return spring.

Gun is lying right side up. Long leg of spring is on top and towards the front of the gun.

The short leg at the rear of the return spring fits in notch cut in the sear. Notch is there at the top.

Once the guard is pinned back into place, only the safety lever needs to be reinstalled.

Have I mentioned yet that these Webleys have single-stage triggers? Well, there you go. The trigger pull weight can be fine-tuned using the set screw at the rear of the blade with a 1/16" allen wrench. By adjusting the set screw to preload the trigger spring, my pull weight was variable from a high of about 4 lbs 2 oz down to 2 lbs 8 oz. Mine is currently adjusted to about 2 lbs 12 oz. Pretty good considering it was in the 8 pound range before the job. It's still not "match grade", but perfectly acceptable for a fun plinker.

Side note: IF the set screw is backed out of the trigger blade more than approximately 0.120" from flush, the gun will fail to cock. The protruding set screw will contact a shelf inside the rear of the trigger guard and the sear will not hold the piston back. Turning the set screw in a few turns will immediately fix the problem.

Warning to Americans: I failed to match up the thread size on the set screw. It's not metric--and it doesn't match up with SAE. It's probably a BA #4. You are hosed if you drop this under a work bench outside of the UK.

Monday, January 19, 2009

A Sight Aperture for a Beeman (Williams) Sport Aperture Sight

I made the mistake of getting a copy of the Brownells catalog recently... So as I was reading through it the other night I noticed that they sold apertures for the Williams range of sights. I have a Beeman Sport Aperture sight on my trusty FWB 124 that has a somewhat dinky aperture with much too large of a hole (.093"). The Beeman sight is made by Williams. I wish I had the "deluxe" version with adjusting knobs, but that's a subject for another day. Anyway, I noticed that the thread size was 7/32"-40 for the thread on the aperture disc. So I quickly looked to see how much a die in that size would cost...$74.95!!! I wasn't about to engage in single point threading a tap to make a die, or threading the aperture disc so the project lost its luster. (My but I'm wordy today) I did find a source for a cheaper die, by the way.

Today I had a few moments to spare so I decided to sort through all of my taps and dies, taking any of the non standard sizes and sorting them in a new drawer unit. Imagine my happiness when I discovered that at some time I had acquired a 7/32"-40 die! Thus am I able to bring you the project below:

The Beeman Sport Aperture Sight (non-deluxe version).

That's a big aperture in that there disc.

The threads looked awfully short, I wonder if the previous owner had knocked a few off at some point?

Turning down the shank on some 3/4" steel.

Drilling #21 (.159")

Drilling #55 (.052") I might make one with an even smaller aperture but figured that this would be a good place to start.

Yawn, yet another picture of me using a die.

I did a straight knurl.

Chamfering the edges.

And cut off from the stock.

Boring out the front.

Just a bit too shiny? I then put it back in the lathe and used a steel brush against that face while it revolved.

I used some Oxpho blue on it. It looks shinier than it is because of the flash.

Much better. I really need to clean that grime off the rifle.

Sunday, January 18, 2009

A Cocking Handle for My RWS (Diana) Model 45, Part 2

Just the shim to make.

Drilling some solid to make tubing...

Turning to fit the brake.

Reaming to the size of the barrel.

Left a shoulder to bear against the end of the brake, the last one had a disturbing tendency to swallow the shim and get all out of place. See, I'm learning! Next one will actually integrate the transition between the two...


The brake was cold blued with Dicropan T-4, the shim with Oxpho blue.

The shim slips over the front sight grooves.

All together.