2250 breach fixing - any good mods?

2250 breach fixing - any good mods?

Joined: September 3rd, 2002, 10:12 am

May 5th, 2011, 9:18 am #1


Hi all.

I've messed with a couple of 2250's  with reasonable results but there is one thing that always bothered me and in my mind downgrades the ability  of the 2250's to take the rough and tumble of  a working guns life and it's the pathetic front breach screw. 
It's really under spec if I'm going to hang a decent length of barrel off the breach without resorting to a barrel band and I'm not fully convinced even with a band!

Has anybody come up with a good way of beefing this up or even a replacement breach that offers a better fixing?


Come to think about it I'm not happy with the front grip frame screw as that seems fragile and prone to wear is there a fix for that?


Many Thanks         Ora

My Websitehttp://eairgun.org.uk/
Last edited by ora8i on May 5th, 2011, 9:20 pm, edited 1 time in total.
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Joined: November 4th, 2002, 9:26 am

May 5th, 2011, 9:51 am #2

Hi
i used the stainless screw from gmac with a crosman steel breech seemed better than std screw
i see your hdd on your website where did you get it & do you know of one available in UK

keith
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Joined: February 9th, 2006, 10:35 pm

May 5th, 2011, 10:45 am #3

Hi all.

I've messed with a couple of 2250's  with reasonable results but there is one thing that always bothered me and in my mind downgrades the ability  of the 2250's to take the rough and tumble of  a working guns life and it's the pathetic front breach screw. 
It's really under spec if I'm going to hang a decent length of barrel off the breach without resorting to a barrel band and I'm not fully convinced even with a band!

Has anybody come up with a good way of beefing this up or even a replacement breach that offers a better fixing?


Come to think about it I'm not happy with the front grip frame screw as that seems fragile and prone to wear is there a fix for that?


Many Thanks         Ora

My Websitehttp://eairgun.org.uk/
I agree with you on that tiny little screw. I like two barrel bands. One as close to the front of the receiver (breach) as possible and one in the usual location. The forearm would need to be notched for clearance of the 2nd band for a 2250 (or 2260).

Haven't thought about the grip frame screw before though.

I plink, therefore I am.
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Joined: November 17th, 2006, 3:51 am

May 5th, 2011, 9:52 pm #4

Hi all.

I've messed with a couple of 2250's  with reasonable results but there is one thing that always bothered me and in my mind downgrades the ability  of the 2250's to take the rough and tumble of  a working guns life and it's the pathetic front breach screw. 
It's really under spec if I'm going to hang a decent length of barrel off the breach without resorting to a barrel band and I'm not fully convinced even with a band!

Has anybody come up with a good way of beefing this up or even a replacement breach that offers a better fixing?


Come to think about it I'm not happy with the front grip frame screw as that seems fragile and prone to wear is there a fix for that?


Many Thanks         Ora

My Websitehttp://eairgun.org.uk/
That rinky-dinky screw, and the short spacing between it and the rear breech screw do not promote stability. Next time you have to breech off, take a look at the actual contact area between the breech and the bottom tube...that's a tiny foot print of contact (and if you check the areas that actually make contact, it is really-really tiny).

The easy way is to go to to one of the aftermarket breeches...at lead the nice square ones, with a large area of contact between the bottom tube and the breech. Same screw system, but with that large an area of contact, they are stable. Would be nice to be able to get the 1700 or 1701 breech (from the pcp pistol...but the bottom tube is the same diameter as the 22XX guns) as it has that larger foot print and is nicely fixed in place by 4 decent sized screws.


The other way is to borrow an idea from the Challenger PCP rifle. It uses a barrel band right in front of the breech. that bad basically ties the b reech end down to the air tube. Have a 177/2250 carbine on the way from the custom shop, as well as a spare barrel band.... but I've tried the trick on a Discovery and two QB's and it does seem to really help the POI stay stable from day to day (or month to month).
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Joined: September 3rd, 2002, 10:12 am

May 6th, 2011, 8:01 am #5

Hi all.

I've messed with a couple of 2250's  with reasonable results but there is one thing that always bothered me and in my mind downgrades the ability  of the 2250's to take the rough and tumble of  a working guns life and it's the pathetic front breach screw. 
It's really under spec if I'm going to hang a decent length of barrel off the breach without resorting to a barrel band and I'm not fully convinced even with a band!

Has anybody come up with a good way of beefing this up or even a replacement breach that offers a better fixing?


Come to think about it I'm not happy with the front grip frame screw as that seems fragile and prone to wear is there a fix for that?


Many Thanks         Ora

My Websitehttp://eairgun.org.uk/
better than a breach with a bigger contact area and use the barrel bands?

ATB Ora

My Website -http://eairgun.org.uk/
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Joined: February 9th, 2006, 10:35 pm

May 6th, 2011, 11:14 am #6

Sorry, it's the redneck in me!

I plink, therefore I am.
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Joined: January 21st, 2011, 6:05 am

May 6th, 2011, 8:49 pm #7

Hi all.

I've messed with a couple of 2250's  with reasonable results but there is one thing that always bothered me and in my mind downgrades the ability  of the 2250's to take the rough and tumble of  a working guns life and it's the pathetic front breach screw. 
It's really under spec if I'm going to hang a decent length of barrel off the breach without resorting to a barrel band and I'm not fully convinced even with a band!

Has anybody come up with a good way of beefing this up or even a replacement breach that offers a better fixing?


Come to think about it I'm not happy with the front grip frame screw as that seems fragile and prone to wear is there a fix for that?


Many Thanks         Ora

My Websitehttp://eairgun.org.uk/
of the breech with the barrel, the breech with the tube or the barrel with the tube. The alignment between the breech and the tube is maintained at the contact between the breech and the tube. It's the same as a dovetail joint. The screws just hold the breech and tube in contact. The clamp strength of a 4/48 grade 5 screw is over 400lbs when properly torqued. I don't know the size of the rear breech screw, but it's safe to say that you have over 1000lbs of clamp force holding the breech to the tube when the screws are properly torqued.

The alignment of the barrel with the tube is irrelevant, but is obtained by the combination of the breech with the barrel band.

The only alignment that is important is the breech with the barrel, assuming you are using a rear sight or a scope mounted on the breech. That alignment is maintained by the large contact area of the barrel in the breech.

The more I study the design of the crosman "tube on a tube" designs, the more I like them. They build a gun of good precision with very few precision machining procedures required. It also makes it easier to modify the guns and repair them because you aren't likely to disturb a precision surface.



"Bones heal, chicks dig scars, pain is temporary, glory is forever."
-Evel Knievel
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Joined: November 23rd, 2004, 12:15 am

May 6th, 2011, 9:19 pm #8

Hi all.

I've messed with a couple of 2250's  with reasonable results but there is one thing that always bothered me and in my mind downgrades the ability  of the 2250's to take the rough and tumble of  a working guns life and it's the pathetic front breach screw. 
It's really under spec if I'm going to hang a decent length of barrel off the breach without resorting to a barrel band and I'm not fully convinced even with a band!

Has anybody come up with a good way of beefing this up or even a replacement breach that offers a better fixing?


Come to think about it I'm not happy with the front grip frame screw as that seems fragile and prone to wear is there a fix for that?


Many Thanks         Ora

My Websitehttp://eairgun.org.uk/
While trying to save a 2240 main tube that had been stripped out twice, I tapped it for a 6-32 screw I had made from a button head cap screw. It worked great and I've now used this mod on almost all of my 22xx conversions, especially long shrouded barrels.

Get it in stainless from Home Depot or Lowes, chuck it up in a drill and go after it with a Dremel with a grinding wheel, then polish.

The only warning is that this is a BIG screw and you have to oversize the hole in the breech. Don't go too big because there's not much of a lip for it to rest on as it is...real easy to ruin a breech.

Glenn in Texas

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Last edited by SeeOhTwo on May 6th, 2011, 9:20 pm, edited 1 time in total.
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Joined: September 3rd, 2002, 10:12 am

May 6th, 2011, 9:28 pm #9

n/t


Ora

My Website -http://eairgun.org.uk/
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Joined: November 17th, 2006, 3:51 am

May 7th, 2011, 12:02 am #10

of the breech with the barrel, the breech with the tube or the barrel with the tube. The alignment between the breech and the tube is maintained at the contact between the breech and the tube. It's the same as a dovetail joint. The screws just hold the breech and tube in contact. The clamp strength of a 4/48 grade 5 screw is over 400lbs when properly torqued. I don't know the size of the rear breech screw, but it's safe to say that you have over 1000lbs of clamp force holding the breech to the tube when the screws are properly torqued.

The alignment of the barrel with the tube is irrelevant, but is obtained by the combination of the breech with the barrel band.

The only alignment that is important is the breech with the barrel, assuming you are using a rear sight or a scope mounted on the breech. That alignment is maintained by the large contact area of the barrel in the breech.

The more I study the design of the crosman "tube on a tube" designs, the more I like them. They build a gun of good precision with very few precision machining procedures required. It also makes it easier to modify the guns and repair them because you aren't likely to disturb a precision surface.



"Bones heal, chicks dig scars, pain is temporary, glory is forever."
-Evel Knievel
..most of the Dicos and 22XX guns seem to not have full contact between breech and bottom tube. If you color the bottom of the breech with soot, attach it, may be in for a shock of how little of that foot print really contacts the air tube.

Some of that may be metal burrs. but often it is becasue the transfer port system is a touch too long(either factory or a poly port) keeps the breech from making full contact.

Yes..the breech alignes to the barrel independently from the fit of the breech to the tube... but unless the breech is firmly fixed to the bottom tube, POI tends to shift.

#1. Make sure the transfer port isn't long enough to act like a "see-saw" and that the breech is down firmly to the bottom tube (but with no leaks).

#2. Pad a vice..clamp the breech to the air tube..then tighten that little rinky-dinky screw down tight. (A large c-clamp, well padded, will work as well as a vice).

#3. You can take a Srosman apart without taking the barrel out of nthe breech...so my barrels use purple lock-tite to the breech. I'll have to heat them to get the barrel out of the breech, but that isn't somthing I ever have to do unless changing calibers.

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