Milling Scope Mount Grooves In The Crosman 180 Receiver

I decided it was time to try my hand at milling scope grooves into the receiver of the Crosman 180. Since the rifle is a beater it wouldn't hurt much if I screwed it up (and I had a backup plan).

I drew up the dovetails in CAD but being paranoid decided to test the dimensions in aluminum rod.

It's good I did as the dovetail was too deep for the mount. Notice the lack of clearance between the mount bottom and the receiver top. Every cheap cope mount is different, and there are no standards until you go with a Picatinny mount system.

So I tried less depth of cut.

Too little.

A tad more (ended up being about .050" groove width) and it looks good.

Then I had to figure out how to fixture the barrel/receiver on the mill. I decided to reference off of the loading cutout.

I finally hit on the method of using a dial depth gage to make sure the slot was horizontal. (a level would have been easier but nothing in my shop is level).

So I checked both sides, tweaked it, checked again until it was parallel to the mill table.

Starting the milling...

I used a lot of oil.

Worked like a charm!

It was a fine balance between depth of cut, position, etc.

The scope mounted right up. My only quibble is I had to make the rear mount more forward than I'd like so it would clear the bolt handle.

I think it looks good.


Just enough groove for the mounts to be solid and about .001" clearance between the mount and the receiver.

Butt Plate For the Crosman 180

This is a boring post, but the work had to be done...

Derrick sent me this butt plate. He has no idea what it's off of.

It had bosses on the underside.

Using my relatively inaccurate method of finding the centerline.

Existing holes plugged and the hole locations marked.

I drilled for the bosses with what turned out to be a very dull Forstner bit. Need to buy a good set of these at some point.

I decided to use #10-24 machine screws. Coarse pitch machine screws work fine in wood, especially dense hardwood.

I marked up the plate with a silver Sharpie and scribed the outline. I nibbled off most of the waste with the bandsaw.

Coarse sanding done. The plate was made of some sort of hellish smelling phenolic. I had to wear a dust mask and basically wanted to burn my clothes afterwards. The dust was that nasty.


I finished up with wet/dry silicon carbide which kept the dust under control. It isn't perfect but it continues the lines pretty well. I would have put more time into it but the material didn't make it fun.

The good stuff comes next...

Another Crosman 180, Part 3

Now to look at the stock.

I got a little aggressive with the belt sander.

There is a lot of wood on the 180 stock.

More sanding.

It cleaned up ok, although there are a few problem areas.

A light coat of cherry stain, then repeated applications of tru-oil.

So the valve body o-ring groove has been machined?

It seems wrong to have an o-ring there without backing.

So I added a smaller one behind it.

The original breech plug went back in and it needed a spacer.

I reassembled the trigger.

Because of all the sanding I did, the post stood proud of the stock. Notice a small amount of breakthrough into the spring recess...

So I drilled out the trigger guard to slip over the post.

And got out my drawer of shim washers.

A spring washer will do the trick.

Works like a charm. It's important that the action not be loose at all in the stock.

All back together. It shot between 575-515 fps over 20 shots at 50 degrees. The last 10 shots fell below 500. It's a bit slow but a lot of that may be the temperature. We'll see if it gets faster in the summer. I thought I'd find a suitable butt plate at the gun show but didn't see anything. So that still needs doing.

Another Crosman 180, Part 2

On I go.

I removed the sling swivels.

And the butt pad.

The rear sight has to come off.

Unscrewing the bolt handle screw.

Bolt and bolt handle.

The screw that holds the barrel down. The bolt has to be removed to access it.

Barrel separated.

It had a nylon tubing transfer port.

This screw holds the hammer.

The hammer unit.

Another post with no way of removing it.

Back to the 3 jaw drill chuck.

Unscrewed easily.

The spacer slid out.

This screw retains the valve.

And I pushed the valve out.

Odd...the o-ring looks too small.

The valve disassembled.

That o-ring has some problems.

It looks like he worked on the valve.