2289 first impressions - aka Doomsday Bugout kit, 1322 variant

[nervoustrigger]

Today I got out in the shop and tore down the 2289 (again), this time for some power mods.

• Made a solid pin for the pump arm - Okay, so this is not a power mod but it makes disassembly and reassembly much easier than banging out the factory roll pin.
• Shimmed the piston cup - Used two washers measuring 0.080" thick total.  This takes up the gap left between the rubber cup and piston to help squish more air into the piston with each pump.  It also has the added benefit of creating a cam-over effect to hold the pump arm closed.
• Added pins to the piston - This modification stiffens the piston to mitigate any tendency it may have to compress while pumping.
• Made poly tube transfer port - Replaced the stock transfer port with a poly tube.  Its cross section is about 58% larger for less restriction of air flow.

The results are pretty remarkable.  Pumping is noticeably more difficult but I am getting almost as much power with 5 pumps now as I was previously getting with 10 pumps.  Now with 10 pumps, the velocity is up 90fps and it's producing almost 50% more power than before.  And the nice part is, everything was done with parts I had on hand.

Here's some photos with markups to help you guys who may be interested in modifying yours.

[griffinhot]

I have followed on this forum some excellent threads on maintenance, repairs, and
improvements to our airguns.  However, for someone who is not well acquainted with
their insides, I found this thread, with its great descriptions and pictures, particulary
valuable and may move me to get out the screwdriver and see what I have been
missing by just enjoying shooting.  Thanks to all who contributed

[nervoustrigger]

Thanks for the kind words, Griffin.

I drafted a summary document with additional details if anyone is interested.  Currently at 7 pages, including a printable scale template for making the barrel band shims.   

https://www.dropbox.com/sh/n3ro6yphs4ql2l4/orhYCuIPBw/Crosman%202289%20mods.pdf

Better get some sleep now

[sshewins]

quick question, what size dowel did you start with to make that pin?

[nervoustrigger]

The rod is 3/16". Please see the PDF for details.

[Strikar]

Did adding the washers behind the pump cup affect the pin alignment of the pump cup and piston holder?

BTW, great post above. Excellent detail and information.

[nervoustrigger]

Yes, definitely.  I just rotated the pump cup 90 degrees and cross-drilled a new hole.   The way I drilled it was by going through the existing hole in the plastic piston, into the pump cup.  I drilled about half way through from each side so the holes met in the middle, in case I wasn't drilling perfectly square.  Worked like a charm.

[nervoustrigger]

To an individual interested in making the modifications to their 2289 or 1377 or 1322 described in my PDF, I am offering to fabricate a set of parts and send to you free of charge.

Just two conditions.  You must provide before and after chronograph results.  And you must endeavor to pay forward a kind gesture to another GTA member...nothing specific, maybe a tin of pellets or parts or helping with a tune.  That is up to you.

First person posting to this thread gets it.  Serious individuals only please.  I reserve the right to ask questions if you are not somewhat established on GTA yet.

[Baltim0re28]

Good deal for someone one here!! Everyone should try to pay it forward.. Didn't mean to interrupt your thread... Should have read the bottom.. SECOND person that posts!!!!

[FNG54]

Read your pdf and now have a 2289 and 1377. I would be interested especially in the pivot pin.

Greg

EDIT: I will pass on your kind offer though. At this time I would not be comfortable working on the valve.(never done it before) And getting the garden in is taking a lot of my time right now.

[backpacker2013]

Hi nervoustrigger,

I am new to the forum.  I have been lurking for a while.  I decided to buy the doomsday kit from Academy Sports $59.99.  I could not pass up this deal.  This will be my first air gun to mod.  I have read your .pdf and would love to have some of your mods to try in my new gun.  I plan on starting a post soon.  My 2289 has the dreaded canted front sight.  I have read that this is common.  I am going to return it for another when I head to town next. 

If you want to give the kit to another more seasoned member I understand,  but again would love to use your mods in my gun.  I will add pics and a post after returning my defective gun.

thanks

[Baltim0re28]

Hi nervoustrigger,

I am new to the forum.  I have been lurking for a while.  I decided to buy the doomsday kit from Academy Sports $59.99.  I could not pass up this deal.  This will be my first air gun to mod.  I have read your .pdf and would love to have some of your mods to try in my new gun.  I plan on starting a post soon.  My 2289 has the dreaded canted front sight.  I have read that this is common.  I am going to return it for another when I head to town next. 

If you want to give the kit to another more seasoned member I understand,  but again would love to use your mods in my gun.  I will add pics and a post after returning my defective gun.

thanks

You don't need to return it. The front sight can be moved with just a few light taps. And BTW, welcome to GTA!! There is a lot of great people and a lot of great information on here!!

[backpacker2013]

Thanks for the tip.  I was under the impression from other posts there is a groove that did not allow it to twist. My entire sight is twisted a considerable amount to the left.  If I can fix it by twisting it then I will try that first.  I just bought it so I did not want to risk braking it with too much force.

[nervoustrigger]

Backpacker, nothing would make me happier than giving these parts to a first-time modder.  PM me your address and I should be able to make them up in the shop one evening after work and get the package off to you.

You will be able to do pre- and post-mod chrony measurements, right?

[backpacker2013]

Yes I will.  Thank you very much.  I look forward to the project.  Will be my first air gun mod.  I have tools and access to a shop.  I will take pictures and post here.

[nervoustrigger]

I would be interested especially in the pivot pin.

Greg, PM me your address.  I'll knock out another pivot pin while I am at it.

[nervoustrigger]

Anybody have chrony info on a flat-top valve and adjustable piston on a 2289? 

 I'm curious how much better it is than shimming the pump cup and pinning the piston.

[Geoff]

since i am thinking of ordering one of these, thank you for the mod tips with instructions.   not sure i would risk tearing mine down, as i have never done it to any air rifle, though who knows what itch will hit me after the initial plinking is done

[nickwild6]

found a guy online that has one of these for sale but it seems to be the older model (no bolt pellet loader) and the barrel is more than two inches longer...is it worth the $50 he is asking?

[avator]

What happened to this thread? I recently bought 2 1377s one of which I've added the 24" barrel and backpacker forearm and stock. I wanted to do some of the mods for the learning experience if nothing else. I don't have a shop but I may be interested in purchasing some of your handywork if you are willing to knock off a couple sets. I've almost completed all the home-tunes on my breakbarrels and the alturnative that I'm trying to avoid filling my free time is that lonely, cold spot on my barstool.... just kidding, there is a time and place for everything.