Sunday, January 19, 2020

Project Updates: .25 Cal QB77

Still nipping away at the old QB77.  A year and a half ago, I converted it from .177 caliber to .25.  At the time, I made a quick carbon extension to hide the 12mm threading at the muzzle.  Didn't take time then to really refinish and blue the modified Benjamin .25 barrel where it fit into the breech.   That cold blue finish hasn't weathered particularly well and I'm now tired of trying to keep after it. 

Click on the pic and it will enlarge.   There's discoloration and spot rusting on the barrel at the breech.

Ordered a longer piece of 3K weave carbon fiber tubing (16mm OD/14mm ID) and waited patiently by the mailbox. 

Rough cut it to length with a hacksaw.  It'll run from the breech to the barrel band out by the muzzle threads.

Gingerly chucked it in the lathe and faced it to final length.

Razor sharp cutting tools are mandatory for working with carbon fiber, otherwise the material wants to splinter.

Some 400 grit paper put a good finish on the end.

Of course there was a snag--the carbon tube didn't quite fit over the barrel. 

Chopped a piece of delrin rod and cut a slit in the end for some emery cloth

120 grit worked well.  In about 20 minutes the tube was a snug fit over the barrel from muzzle to breech.

The barrel band will sit just aft of the muzzle thread.  The short piece covering the muzzle will butt against the band.  Should look like a continuous piece of carbon.

Backing up for a second.  This is what the QB77 looked like before all this madness started.  Pretty much a modern day version of the old Crosman 160/167.

This is where I'm at right now.

I've covered many of the modifications here on the blog.  The extended bulk fill gas tube, the AR2078 stock, adjustable recoil pad and barrel band...

At some point, I made a screw cup, fit an accessory rail, and made a knurled hand stop and cuff sling.

Took some time, but the QB has gone from a rifle I couldn't connect with to one of my favorites.   Not done yet.  There's some valve work on the horizon to find a bit more velocity for the .25 pellets. 

Thanks for checking in.

Friday, July 5, 2019

A Very Special Morgan Adjustable Recoil Pad

If you've followed this blog for any length of time, you know of our affinity for Morgan adjustable recoil pads.  A few weeks ago, I came across an eBay listing for a model I'd never seen before.  The shoulder "pad" (and I use that term very loosely here) is solid, shiny, beautiful diecast aluminum.  It's clearly a very early model--possibly made for small bore precision rifle shooting. 

I contacted Dave Brush, the current owner of Morgan Recoil.  He's the nephew of the company's founder, the late Bill Morgan.  Dave was not aware of this all aluminum model and could find no record of it in the company archives.


The casting is marked W. J. MORGAN.    Some additional markings below that were worn away long ago.  My best guess would be "Youngstown, OH", based on other Morgan rubber recoil pads I've had over the years.   The inside of all the castings are marked "ALCOA". 

The "base plate" on this unknown model is identical to the base plates on the first generation rubber Morgan recoil pads.  "First generation" sounds so old, but it just refers to the interlocking grooves between the base plate and center plate used to hold the pad's vertical adjustment   The manufacturing molds were damaged several years ago and Morgan updated the plate design.  They're not cross-compatible. 

There's a missing hard foam spacer that should go between the shoulder "pad" and the center plate.  The upper and lower screws will then allow you to toe, or tilt, the pad up or down a few degrees.

I purchased a current foam spacer from Morgan but it didn't fit quite right.   Ended up making my own from a piece of 1/4" thick closed cell foam.   The one I made is pictured here.

Glued it to the aluminum with a quick setting two-part epoxy.

Attached to the center plate and ready to go.

Bolted right up to the base plate already on the .20 cal Benjamin Sterling.

I'll keep looking around for additional info.  It'd be interesting to know when this was produced.  Morgan's website notes that the company was started before WWII, so it could be pretty early.     Maybe some old gun magazine advertisements would shed some light.

Thanks for checking in.

Sunday, May 5, 2019

Installing Crosman's Two-Stage Trigger on a 22XX -- Part 2

Working out the final details of the two-stage trigger installation, I noted at the end of the last blog that that, "A stock 22XX hammer will ONLY work if you pull and hold the trigger to the rear while cocking the gun.  With the bolt pulled completely to the rear, let go of the trigger and the sear will catch.  Yeah.  Great.  I've read that the hammer from a Crosman 1701P will solve this problem.    I've also read that a 1701P hammer will ONLY work in the 22XX gas tubes.  It's too large in diameter for the smaller 13XX compression tube...Of course, I found out about the hammer after I'd ordered all the other pieces parts from Crosman.  Rather than another order and another week for delivery, I made a couple new hammers."

Here's the hammer from my 7 or 8 year-old Crosman 22XX.

The new two-stage trigger sear hangs up on that big groove in the middle.   One easy "no machining solution" is to simply fill the groove with something like JB Weld epoxy.  Probably not even necessary to fill the entire circumference.  Just the bottom area where it rides over the sear should be sufficient.

Also note that this is an earlier model hammer for the forward breech mounting screw.  It does not have the clearance cut at the front to work with the newer breech screws that are accessible only after removing the loading bolt.  So, there's one less machining step for me.

To make a new hammer, I used a piece of 0.750" diameter W-1 (the W denotes "water hardening") tool steel.  

All dimensions came from the removed Crosman hammer.  Turned the OD down to 0.739"

Chamfered the end.

Spotted for the hammer spring hole.

And drilled 5/16"

Cut to length and turned the angle on the front for the sear.

Went to the mill, did some quick edge finding and spotted for the hammer pin.

0.125" drill.

A 3/16"  (0.1875") end mill was used to cut a short counterbore.

Pretty much done.  Not gonna worry about matching the exact weight to the original. 

I'm sure it was usable as it was, but I did a quick and dirty heat treat to the face of the hammer to keep it from wearing.  Heated it to critical temperature and quenched.  A bit of tempering brought down the hardness slightly.  Polished it up and installed. 

Really like the adjustment range of the two-stage trigger.  With that window cut in the side plate it was very easy to see exactly what was happening as the first and second stage were dialed in.

Thanks for checking in.  More soon.

Sunday, April 28, 2019

Installing Crosman's Two-Stage Trigger on a 22XX -- Part 1

Crosman has been using a new two-stage trigger compatible 22XX grip frame for a while now but only installing the simpler single-stage trigger parts.  So, if you have the new style grip frame (or buy one) and want to upgrade to a true, two-stage, fully adjustable trigger for your 22XX style gun, it's possible to order the parts directly from Crosman.  Looking around online, I found a few tutorials on how to make the parts retrofit, but most glossed over the problems I ran into.  Anyway, here's the details of my conversion and the minor headaches you'll experience if you go down this road.

This is my original old-style 2240 single-stage grip frame and trigger components.  The cover plate is diecast and held by two screws.  This grip frame will NOT fit the new two-stage trigger parts.

Here is a new style grip frame and the necessary two-stage trigger parts.  The cover plate is plastic and held by three screws.   These three screw frames will accept either single or two-stage trigger components.

The first problem I ran into was my grip frame did not have a hole to reach the set screws to set up and adjust the new two-stage trigger.  I don't remember where I got this grip frame--it's probably from a 2300S.  It's likely that this hole will not be drilled in the new frame if the gun is sold with the single-stage trigger set up.

Spotted and drilled a 1/4" hole. 

I also spotted, then drilled, for a trigger stop using a #29 bit.

Some small taps.

A pin vise gave the necessary extension to cut the #8-32 thread.

A #8-32 set screw and a drop of loctite and the frame is now ready to go.

With the frame prepped, I could start assembling the two stage parts.  For a list of the necessary parts I went to Crosman's site and download the EVP for the Crosman 1701P pistol.  I called Crosman with the part numbers and ordered everything on the grip frame schematic that I didn't have. 

So here's how it all goes together.  Starting with the trigger:

Install the safety and then the trigger with the two adjustment set screws and trigger pivot pin.  Initially, I used teflon tape on the threads of the set screws.  This was a mistake.   Use a medium strength loctite instead. 

Install the trigger spring.

It goes over the link pivot boss.  Note the lower leg sits on top of the trigger between the two set screws.

Now the trigger link:

Install the link and link pivot pin.  Note that the upper leg of the trigger spring is on the underside of the link.  Click on any picture to enlarge.

The spring adjuster assembly was next:

Link spring goes in the housing.

Push it all the way though.

The tail is captured in the counter bore.

The brass adjuster screw threads through the spring using the coil itself as the thread.

It's threaded all the way through like so.

Then the tiny #0-80 locking screw is threaded into the end of the brass adjuster.

Install the adjuster housing assembly:

Hook the end of the spring to the trigger link.

The post in the grip frame holds the adjuster assembly in place.

The sear is last:

The sear spring is installed in the top of the adjuster housing.

The sear is then installed.  Tab at the bottom of the sear goes into the spring, then the sear is swung into place and onto the sear pivot pin.

The cover then goes on and I thought I was done.  Nope.  The new trigger is a huge pain in the ass to adjust.  With the cover in place, the adjustments to the trigger set screws are blind.  Removing the cover made the spring loaded components pop out of place and onto the floor.  It's 2019.  This is supposed to be easy.  Took a que from a feature Crosman used (in the mid 1950's!) on the trigger housing for the 160 CO2 rifle. 

Removed the side plate and with a 5/16" endmill, I cut a hole--to see what the set screws were doing against the link.

The hole is pretty much in line--and just behind--the safety hole.   I did make sure the grip would just cover the hole.  This COULD be done on the other side in the metal grip frame--but if you screw up, remember that it's more expensive to replace the metal frame than the plastic cover...

Like a window into my soul.

I really can't believe this isn't done at the factory.   Anyone have a Benjamin Marauder pistol?  Is there a hole in the grip frame or the cover?

A quick test fit shows the hole is covered by the stock Crosman grip panel.

The trigger set screws require a 0.050" hex wrench.  I found that a Bondhus hex driver worked perfectly.

With the grip frame installed, the window made it easy to adjust the two stages perfectly.  The front screw adjusts the length of the first stage.  The rear screw, the second stage.   I wanted the first stage relatively long and with a solid "wall" when it transitioned to the second stage, then just a bit more pressure (but no perceived travel) to fire.  To do that, I screwed the front screw in further than the rear and played with the adjustments while cocking and dry firing the pistol.  Backing out the link spring tension adjuster also let me dial in the feel.  When finished, I adjusted the trigger stop so the trigger stopped cold at the moment of firing.

A couple more snags:

First, while the stock Crosman/Benjamin plastic grips are good to go,  most custom wood grips will NOT fit without additional inletting.     The adjuster housing body stands proud on each side of the frame, so a wood grip will not seat flush to the frame without adding some extra clearance.

Second,  a stock 22XX hammer will ONLY work if you pull and hold the trigger to the rear while cocking the gun.  With the bolt pulled completely to the rear, let go of the trigger and the sear will catch.  Yeah.  Great.  I've read that the hammer from a Crosman 1701P will solve this problem.    I've also read that a 1701P hammer will ONLY work in the 22XX gas tubes.  It's too large in diameter for the smaller 13XX compression tube.  So there's the warnings. 

Of course, I found out about the hammer after I'd ordered all the other pieces parts from Crosman.  Rather than another order and another week for delivery, I made a couple new hammers.

That'll be the next post.