Crosman 2100/766/Legacy 1000 Bolt

[Ronno6]

I have been nudged into looking at making a bolt w/brass probe and O-ring for the 2100/766/Legacy 1000 rifles.
Looking at the factory fitment of bolt probe into the leade I am very surprised at how much slop there is!
I can see why Crosman covers the loading port with a sliding cover....it masks the blowback.....

[Blowpipe Sam]

I'll buy one!  I've often thought an O ring for the probe would improve sealing but the breech assembly also needs to be sealed better.  I agree that the loading gate is necessary.  With the loading gate closed the 2100 is pretty well sealed against dirt and crud.   

[Ronno6]

I had never really measured a Crosman 2100 bolt before.
I had thought them to have a .177" probe, but do not.
It is larger.like .1835 along the length, and only necks down to .180 near thr tip.
And there is SIGNIFICANT slop between the probe tip and the leade in the loading port.
Probably allows a bunch of blowback..

Anyway, I have to try a couple different O-rings to see what will work best, and have ordered a couple sizes.
The ones I use for Daisy may be a tad small, as Daisy's loading port and bolt probe are closer to .177.

Crosman could not use an O-ring with their magnet as there would be no material left between the bottom
of the O-ring groove and the hole for the magnet...........I discovered that on my own.
On my Daisy bolts I have started using a smaller dia. magnet and fully pushing it into a brass sheathe at the tip.
That protects the magnet from breaking, as they are fragile.
So far so good on that one.
Should anyone want a 2100 bolt w/magnet, that is what I will need to do.

The odd probe size will mean that I will have to machine the OD of the brass stock.
However, I may end up leaving most of the plastic probe in place and adding a brass tip w/the O-ring and magnet.

Actually a brass tip w/O-ring that presses into the original hole for the magnet would work if super glue would hold it in place.
I typically drill and tap both the plastic and brass probes and use a set screw to join.

I'll keep you informed.

[gloob]

Interesting find. 

Mine is about as accurate as anything, having been shimmed and glued to reduce barrel/receiver movement. 

I just took her out to the backyard to reconfirm this to myself. Took aim at a sliver of yellow just barely peeking over the rock wall of my garden at 22 yards, rested. Not sure if it was an orange or one of my yellow foam golf balls. One shot made it bounce up into view. Foam golf ball. I only have a few rifles that would make this shot.

I chronied 5 shots at 4 pumps.
527.8 minimum, 530 maximum. 7.5 gr wadcutter.

If there's a leak, it doesn't seem to affect accuracy!

[Ronno6]

Interesting find. 
If there's a leak, it doesn't seem to affect accuracy!

Accuracy...probably not, as long as it leaks the same for every shot.
If it is accurate when it leaks, it should be the same when better sealed....... IMO

[gloob]

Hopefully you can find out. Chronograph is not exactly equal to accuracy, but it's a lot quicker and easier than shooting groups. Might even be a better test, on a 2100. Out the box, there's too much play in the barrel-to-receiver to really test the effect of a better sealing bolt, IMO.

The effect on power might also be interesting.

I figure my numbers are at least something to compare, in case you didn't chrony yours before taking it apart. I had mine apart, once, and it's not hard, at all. Putting it back together...

[Ronno6]

I figure my numbers are at least something to compare, in case you didn't chrony yours before taking it apart. I had mine apart, once, and it's not hard, at all. Putting it back together...

I have a wood fixture that holds the barrel, pump tube, RH receiver and stock in the proper orientation.
Assembling the LH receiver is typically a matter of getting the safety lined up......

[Blowpipe Sam]

I figure my numbers are at least something to compare, in case you didn't chrony yours before taking it apart. I had mine apart, once, and it's not hard, at all. Putting it back together...

I have a wood fixture that holds the barrel, pump tube, RH receiver and stock in the proper orientation.
Assembling the LH receiver is typically a matter of getting the safety lined up......

I built a wooden fixture to reassemble my Legacy 1000.  It definitely made it easier.  The slop in the clamshell is a significant problem for the 2100.  I've been thinking recently that one or perhaps two simple fixtures could be 3D printed and fitted inside the clamshell to wedge the action immobile when the two halves were tightened.  Disigned properly it could also wedge the barrel and the compression tube more firmly together.  What think you?

[Ronno6]

Thinking is painful..........
Hard to envision your design, but I'm sure it would help.

[gloob]

The slop in the clamshell is a significant problem for the 2100.  I've been thinking recently that one or perhaps two simple fixtures could be 3D printed and fitted inside the clamshell to wedge the action immobile when the two halves were tightened.  Disigned properly it could also wedge the barrel and the compression tube more firmly together.  What think you?

The wedge-action would help take out some slop. I jammed a brass shim between barrel and pump tube, forced towards the receiver. But this shim is only 14 thousandths of an inch thick. I dunno if that's something you would want to 3D print out of plastic.

As for "wedging" the barrel and compression tube more firmly together, I highly doubt that would do anything. These parts rack and twist against each other, changing the POI. No matter what you simply put between there, these two tubes can twist around in there, still.

I hot glued two long brass tubes in the "V" on either side of the barrel and pump tube. My scoped 2100 holds its POI for probably over a year, since I did this. You just need a small torch or hot air gun, along with a glue gun and good hi temp glue sticks. I can't remember how big these tubes are, but they're the largest diameter that the pump arm closes over without touching.

[ricksplace]

I replaced the magnet with a (thinner) longer machined brass probe. I made it a snug fit in the bolt. It stays put without glue. I put shrink tubing around the plastic part of the bolt to reduce the blowback. You can feel the snug fit when closing the bolt. I probably have about 1000 shots through it and the shrink tubing is holding up well without shredding.  (surprising!)

[Ronno6]

I replaced the magnet with a (thinner) longer machined brass probe. I made it a snug fit in the bolt. It stays put without glue. I put shrink tubing around the plastic part of the bolt to reduce the blowback. You can feel the snug fit when closing the bolt. I probably have about 1000 shots through it and the shrink tubing is holding up well without shredding.  (surprising!)

Excellent!

[Ronno6]

I have modified a couple 2100 bolt bodies for attaching the brass probe.
One has plastic for 1/2 length, then brass to the tip and O-ring.
I bellieve that will work.
I have also done one wirg a full length brass probe.
I think that will work also.

From a user's point of view, would one be preferred over the other??

Just waiting for 0-rings to play around with fit.......

[longhunter]

I would think that a full length brass probe would be stronger, in the long run, would it not?

[Tack Driver 10]

This is how I modified the probes on the 2100/2200 guns.
Turn the probe shaft down and thread it 8-32.
Then make a brass probe with internal threads to match.
Don't remember what size o-rings used.

[ricksplace]

My (1997) 2100 was a purchased in an unworking condition. I already owned a Daisy 880 that was so darn accurate I didn't look at any other pumpers. The price was right so I bought the 2100. When I took it apart, I noticed that the bolt wouldn't close all the way. There was a transfer port up close to the muzzle. I'm pretty sure transfer ports aren't usually up by the muzzle. Yup, the barrel was installed backwards. It's no wonder the bolt wouldn't close since it was trying to jam into the muzzle! The gun is a Canadian model with the pressure bleeder in the valve to limit pressure for sub-500 fps regardless of how many times you pump it. This makes the Canadian valve larger internally to accommodate the bleeder. I plugged the bleeder port by machining a brass plug and soldering it in place. 4 Pumps gives right around 500fps, so that's where I shoot it most of the time (I'm not fond of pumping). The larger internal volume permits pumping well past 10 pumps with no valve lock, no retained air, and a stock hammer spring (15 pumps gives 780 fps, but I usually don't...). After a re-crown, re-assembly and the assorted mods that most people do,  the darn thing is more accurate than my 880! I put a 4-16x40AO on it to take advantage of its performance. It's a keeper.

[Ronno6]

I would think that a full length brass probe would be stronger, in the long run, would it not?

The weakest link is the hammer pin cocking slot in the underside of the bolt carrier body.
That fractures over time with repeated cocking.

Second is the plastic tip that holds the magnet.
When the plastic tip fractures the magnet escapes and the bolt is useless....

Problem with the lull length probe is that there is only a thin web of plastic on the front of the bolt carrier.
Like 3/32" thick. That'll only allow for under 4 threads engagement of a 5-40 stud.
Granted, the highest stress will be when loading, so that might not be a major concern,
However.........the mounting stud hole breaks thru to the hammer pin slot. As mentioned above, that is the point where the
bolt carrier fractures due to cocking. That is probably not a favorable side effect.

At least a 1/8" of a nub of the plastic probe would be essential to prevent weakening of the bolt body.
At that point, it really matters not whether the plastic probe remnant is 1/8" or  1" long. I think 3/4" will
be used as it is 1/2 the OAL of the bolt probe.
Major point of concern is getting the end of the shortened probe square in order for the brass extension to butt up straight.
Don't want a bolt probe with PD.........

I am finding the O-ring groove dimension to be rather fussy, with a very narrow margin between too tight (bolt will not close completely)
and too loose O-ring contact (O-ring will not seal.) The opening of the leade is a fairly sharp corner, so a tight fitting O-ring may see some chafing.
I will look at moving the O-ring closer to the tip so that it seals in the barrel rather than the loading port....

Product development is.............fun (?)

[Ronno6]

This is how I modified the probes on the 2100/2200 guns.
Turn the probe shaft down and thread it 8-32.
Then make a brass probe with internal threads to match.
Don't remember what size o-rings used.

I do similar on the 2200 bolt, except I use a 4.5mm thread...no need to turn down the original probe stem.
That would be a tad more difficult for the 2100 bolt.....that WOULD require turning the probe base down, and that may be tricky.
As shown in your photos, that requires removal of the loading port shield.......

[happymecanic]

Here's how I did it on my 766, oring is from a cheap lighter (metric?). Top is a stock AM77 bolt, bottom is the modified 766 bolt.

[Ronno6]

Here's how I did it on my 766, oring is from a cheap lighter (metric?). Top is a stock AM77 bolt, bottom is the modified 766 bolt.

Merci, Francois...
However, the lack of a magnet would mean no BB's...unless you keep the muzzle pointed upward...