Sharing 13xx mods.

[DavidS]

I realized that while there are many threads on 13xx platform gun modding, there is none just to share all of the mods that a number of people have done.

I suggest that, in this thread each of that wishes to share give a list of the mods to each od our modded 13xx series guns (including the 2289).  And then be willing to answer any questions on details of the mods that we have made.

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So I shall begin with my 2 main 2289's and 1322:

First 2289 is set up for good power and accuracy.  This is a long barrel (18 inch) Carbine.
The modifications that I have done with this one are:

• Back to the plastic breach and a 14 inch barrel.Crosman Steel breach.
• Cut a 24 inch Crosman barrel to 18 inches, cut a custom crown, polished the crown.
• Polished the barrel lead, and lightly polished the barrel.
• Bored the port into the barrel from the transfer port to .18 inches.
• Reinforced the barrel band with some rubber.
• Weakened the valve spring.
• Put a 1/8th inch steel rod in the face of the check seal to fill the extra inlet space
• Bored out and angled the valve exaust port.
• Shaved the nose of the valve to match the pump cup.
• Turned down the valve stem where it clears the port when open to allow more air flow.
• The standard Poly tube transfer port mod.
• Extended the bolt probe (turned down the nose, drilled for 1/8 inch, and epoxied a 1/8 inch OD steel rod in and cut back to only stick out enough to clear the TP).
• Weakened the trigger spring.
• Made an insert for the trigger spring to give the sear a flat smooth surface to contact the spring.
• Polished the trigger, sear, and hammer contact surfaces, and completely polished the hammer.
• Installed a 760 hammer spring.

• Stuffed the piston with 3/16th inch steel rod.
• Polished the inside of the pump tube.
• Shimmed the piston cup.
• Added mass to the hammer by fusing lead to the center of the hollow inside of the spring ID.
• Wrapped enough Teflon tape around the portion of the valve between the O-Ring and face to fill the gap to the tube walls (reducing head space).

The second 2289 is setup as a multishot ACP, and it does very well.
Mods for the second 2289 (ACP).  This rifle will produce 4 good shots at 30 pumps (actually 28 or 29 from empty) with a touch of air left; it can be set for fewer shots at greater power if needed.

• Everything that I did to the first 2289, with the following added/Changed.
• Increased the internal volume of the valve by cutting a couple of threads.
• Weakened the hammer spring until the balance of hammer mass and spring did not give any bounce.
• Made a pop out screw type cam over pressure indicator.
• Shaved down the size of the check seal (increasing internal valve volume).
• Made a power adjuster (so that I could get the shots precisely tuned).

The 1322 is setup as a short (14 inch barrel) pistol/carbine (easy to switch between pistol grips and 1399 stock).

• Everything as the first 2289, except the following differences.
• Made an aluminum adjustable cup piston.
• Cut the barrel to 14 inches instead of 18.
• Cut slots in the pistol grips and 1399 stock at the screw holes for quick fastners.
• Made some simple twist and push quick fasteners to replace the grip screws.

I have tried other mods over time some of which worked and some that did not.  So now for a list of the mods that are not in the above mentioned 13xx's.

• Made an adjustable flat top piston (works though not as well as the cup piston mods).
• Flat topped a valve (modded in the same way as my first 2289, though flat topped).
• Floating barrel (not worth it at all).[/b]
  
  • Pressure gauge on the valve of the ACP (Not worth it).
    
  
  
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  Ok I have shown you mine, lets hear about yours .
  
  Note that the above lists may not be complete, I am going from my memory, combined with scattered notes, and looking at the guns.    Also none of my mods change the appearance of the 2289 (I like it as it came for appearance).

[DavidS]

And proving that this is a never ending hobby:
This evening I put the stock plastic breach and a 14 inch barrel on my primary 2289 (the first one in the mods list.

I did this so that I can use it in open sight competitions.   The other two still have the steel breach.

[YEMX]

I haven't built it yet, but here goes:

Custom length 13xx tube
FT 13xx valve
Custom 2100 FT adjustable piston
2100 pump arm (or a custom one, not sure yet)
BNM breech w/BAM 50 bolt knob
Shrouded barrel
Disco trigger group w/brass trigger and 2 screw mod

I haven't decided whether or not this will be a side pumper (like a Daystate Sportsman II), or a standard pumper...  I'm leaning towards the side pumper so I can have a solid stock.  I'll have a custom barrel band/end cap made so that the band is also the mount for a globe sight.  In my head, it looks like a sweet little pump carbine!  Overall, I'm trying to clone the Sportsman II, but using mostly U.S. made parts.  I also wanted it to be shrouded (unlike the Sportsman) for quiet fun! 

[ToRmEnToR]

Following with interest

[DavidS]

Am I the only one that thinks putting lists of our mods in a single thread to allow people to ask questions is a good idea?   I know that there are other 13xx modders on these forms.

[WECSOG]

I think it's a great idea! 

My 2289 is currently stock, but I have a flat top piston for it and I plan to mod the valve myself. 

[YEMX]

I think it's a fine idea- it lets those of us that want to participate to swap info about our builds... You know, the "why" and "what for's"...

[rsterne]

While not a list of mods, here is the definitive testing of the effect of different types of pistons in the 13XX / 2289 platform....

http://www.gatewaytoairguns.org/GTA/index.php?topic=77463.

This should clear up any misconceptions about the effectiveness of the different types....

Bob

[WECSOG]

Thanks, Bob. That's a great addition to this thread!

[DavidS]

While not a list of mods, here is the definitive testing of the effect of different types of pistons in the 13XX / 2289 platform....

http://www.gatewaytoairguns.org/GTA/index.php?topic=77463.

This should clear up any misconceptions about the effectiveness of the different types....

Bob

Thank you for linking that in Bob.

I always knew that any cup piston would have its limits.   I would like to see the data on a stuffed and shimmed piston (done correctly and carefully with all 8 cavities stuffed) as my penitration tests show that it is very close to the aluminum cup piston (not sure how close, though it seems to be closer to the aluminum cup piston than to the stock piston).

I still prefer the cup piston, of course I also tune for lower pump counts (under 20), unless playing with ACP and then the valve volume is increased anyway.

[rsterne]

I didn't bother with the stuffed piston as that is open to much individual variation, from poorly done to nearly as good as an aluminum piston with cup.... All of them will lie between stock and the adjustable aluminum piston with cup and modified valve face.... and can be nearly as good as a flat-topped piston and valve up to about 10 pumps.... My testing showed that 12 pumps with the F-T-P equaled 13 pumps with the aluminum cupped piston.... Above that the difference was more than one pump and growing....

Bob

[DavidS]

I didn't bother with the stuffed piston as that is open to much individual variation, from poorly done to nearly as good as an aluminum piston with cup.... All of them will lie between stock and the adjustable aluminum piston with cup and modified valve face.... and can be nearly as good as a flat-topped piston and valve up to about 10 pumps.... My testing showed that 12 pumps with the F-T-P equaled 13 pumps with the aluminum cupped piston.... Above that the difference was more than one pump and growing....

Bob

Thank you for this great data.

I still that this thread will attract more 13xx modders.

[plinker99]

Here's one I posted on cap of last year for a 2 stage trigger for a 1377.........

   i got the first try at this 1377 2 stage trigger done.  i slightly miscalculated the drilling of the screw hole for the 2nd stage adjustment.  i'll try again later.  for now i need to see how this shoots.  using my spring scale, the 1st stage pull is about 8 - 10 oz.  the 2nd stage break is about 1lb. 3oz.  here's some pics....
   i have to say that this is not entirely my own idea.  there was a post on a form somewhere a few years ago about setting the the first stage using a stiff wire soldered to the sear going over the safety.


This is still a work in progress project.

Edit...to do this mod, the safety ball/spring slot in the  trigger frame needs to be modified as shown....

[JMJ in NC]

My modifications, with the reason for each listed after.

Gun started out as a $35 refurbished PC77 (1377).

Aftermarket Parts:
Mellon flat top piston - efficiency
Mellon flat top valve (ported) - efficiency
Mellon pivot pin bushing/arm support - consistency
Mellon extended probe bolt - efficiency
Mellon Power Adjuster - consistency
Crosman steel breech - consistency
Crosman 24" barrel - efficiency
Crosman 2289 forearm - ergonomics
Crosman 1399 rear stock - ergonomics
Crosman Discovery hammer spring - efficiency
Crosman 1701P trigger - consistency
Chavka barrel band & pivot pin - consistency
Leapers 3-9x40 AO IR mil-dot scope & medium rings - consistency
Lead Shed - ergonomics

Modifications:
JMJ 17" LDC/shroud - quietness, consistency (barrel stiffness)
Threaded & crowned barrel (3/8"-16 male) - consistency
Added second set screw on steel breech - consistency
Delrin bushing on rear of Mellon bolt - consistency
Black satin paint on forearm & LDC - cosmetics
Plugged forearm roll pin holes - cosmetics
JMJ adjustable Kydex cheek riser - ergonomics
JMJ adjustable butt-pad - ergonomics
JMJ Lead Shed mount - ergonomics
JMJ stainless steel safety pin - ergonomics, cosmetics
#6-32 set screw on power adjuster & ribbed exterior - cosmetics
3rd stabilizing screw in rear stock - consistency
Brutuz-type port seal - efficiency
JMJ scope level - consistency
JMJ flat trigger shoe - consistency, ergonomics

Performance: 705fps with 8.4grain JSB Exacts at 10 pumps. Sub .25" groups at 25m (rested).





JMJ

[nervoustrigger]

Some low cost power and accuracy mods are detailed in this thread...shimming the pump cup, stuffing the piston, stabilizing the barrel band, etc.:
2289 first impressions - aka Doomsday Bugout kit, 1322 variant]

Mine started out as a 2289 (.22 cal).  I wanted flatter trajectory commensurate with the powerplant so I converted it to a long-barreled .177:
Crosman parts finally came! - .177 cal conversion of 2289

It prints 0.3" - 0.4" groups at 25 yards.  My buddy at work has it at the moment and it's bad news on the squirrels in his back yard 

[DavidS]

Some low cost power and accuracy mods are detailed in this thread...shimming the pump cup, stuffing the piston, stabilizing the barrel band, etc.:
http://www.gatewaytoairguns.org/GTA/index.php?topic=44342.0

Mine started out as a 2289 (.22 cal).  I wanted flatter trajectory commensurate with the powerplant so I converted it to a long-barreled .177:
Crosman parts finally came! - .177 cal conversion of 2289

It prints 0.3" - 0.4" groups at 25 yards.  My buddy at work has it at the moment and it's bad news on the squirrels in his back yard 

Good results from minimal mods.    I had done a bit of valve work before I stuffed my first piston, and that before doing the poly tube TP, so I had no idea what it could have been with out the valve work.

[Rescue35]

Im about to rework my 1322 and maybe rebuild my pc77.

I currently have them set up with my own flat top piston and valves. The 1322 has a 14.5" barrel and 2289 pump grip. Its waiting on a steel breech and mim sight from crosman. I will be upgrading the pump linkage, endcap, and cross pin.

[DavidS]

As a note I put the Steel Breach and 18 inch barrel back on my main 2289.

For any that wish to know, with the steel breach, for short range shooting I use a TruGlo Red Dot sight.  Here is a link to the TruGlo Red Dot that I use:
http://www.dickssportinggoods.com/product/index.jsp?productId=4018614

And with the steel breech I use the CenterPoint 4-16x40mm AO scope with mil-dot reticle for long range shooting.  See this link:
http://centerpoint.crosman.com/scopes/power/CPA416AORG2

The open sight competition that I was to attend is restricted to .177 cal only for AirRifles, and they will not let an AirRifle in the .22 rim fire competitions.   To bad as the .22 rimfire competitions only go out to 50 yards so I could have done well.

[YEMX]

is a 760's hammer spring stronger than a 13xx's?  Is it longer?

[DavidS]

is a 760's hammer spring stronger than a 13xx's?  Is it longer?

Yes quite a bit.   It is common place to use a 760 hammer spring in a 13xx to easily dump more are than you can with the stock 13xx hammer spring.