My 1325XLT is now a 1322XLT

[K.O.]

And will not dump more than 10 pumps...

with the .25 barrel and .180 by  .219 barrel port  and  .220 transfer port it would dump 22 pumps...

well anyways I shortened the disco barrel to 22" in honor of the pump tube being from a 2100 (21.8"), plus I had to get rid of the boogered

up muzzle portion (come on Crosman  ).

did a quick crown...

Milled a .25 sealing flat for the .220 transfer port.

Ported the barrel to .160  ( it obviously need at least  .160 by .180-.190 oval port)

Oh yea I finally stuffed the 13xx portion of the piston.


According to the spreadsheet (Boy do I wish I had a copy) it was 67% efficient pushing the  20.1gr .25 pellets to 630 fps.

I am hoping to hit at least 725-750 fps with 14.3gr pellets.

maybe my ears are fooling me but at 10 pumps it sounds faster than my 1322MLT at 15 pumps

will soft chrono in a while and then again after I  oval port the barrel...



I have some thinking to do maybe add a bit more preload to the 13xx striker/2200 spring it already has a 25gr .25 pellet smashed in the striker.

I ported and it did not make a bit of difference it still will not dump more than 10 pumps


pumps      fps

5              495, 500, 498
7              591, 585, 592
8              626, 616, 616
9              654, 656, 657
10            673, 687, 680
11           653-580 wonky as heck did not measure 2nd shot just cock and dumped.


I guess  stuffing the 13xx portion made a bigger difference than I thought and pump effort is way up way sooner...

well  It is sneaking up on  700 fps at ten pumps not bad but I am power hungry I want it to dump 14-15 pumps...

I know it can be done a friends dad did one(2200) for me in the 80s.

For those who do not know about the 1325XLT 

http://www.gatewaytoairguns.org/GTA/index.php?topic=60800.0

[K.O.]

added about .25" of preload at striker spring and think I can add about .125" more before coil bind.   

dumps 11 pumps now but not 12

will test fps again Sunday afternoon...

[woody67]

You most likely know this already, but if you put a lighter spring inside your valve, you shouldn't have any problem dumping all the air (especially if you are using a heavier hammer spring).

Also, the .22 barrel is a little smaller than the .25 barrel...could that be why you aren't dumping all the air like you were before? 

[K.O.]

Hi Woody here is some updating
http://www.gatewaytoairguns.org/GTA/index.php?topic=71412.0

I have more work and testing to do but have not felt real great for the last week or so so by the time I get done with the other things you have to do in life... well I have been taking a break...



will be getting back to it soon...

[K.O.]

Well I finally had a chance to test with the .25 barrel back on.

pumps    fps

7           503
8           540, 538
9           580, 580
10         593, 597
11         610,  548-378,  580-no capture...

So yep even though the valve volume is much more suited to a .22  I think if I get off my rear and do some work and make another exhaust

half for the valve I should be able to dump closer to 15 pumps and just maybe hit  640 650 as a .25 and 750 or so as a .22 but that is more stress than I think is good for it and 12 or so is about as far as I want to push it and only a bit here and there...

So the .22 barrel is going back on and most of the time will be pumped to 8-9 pumps.

I will also do my best to build another in .177 shooting for about 800 fps in 11 pumps...

Hey the pump tube and lever are only about  15 bucks... and I do have the rest as a 1377 18" carbine.

right now I just need to see if the Mk177  valve nose will work may not have to go custom.


I think not bad for sticking with a rubber pump cup.


The 1325XLT, well making way for the 1325MLT it is going to send the lead  down range faster(but more pumping which does not bother me)

it will use a 66 pump and modded valve...

Stay tuned...