Started my 1325XLT project wish me luck :)

[K.O.]

Rather  than repeat myself,

http://www.gatewaytoairguns.org/GTA/index.php?topic=59377.0

Thoughts

Critiques

W.A.G.s  about fps to expect or any

good luck wishes  appreciated.

[1377x]

have you seen this thread
http://airgunhome.com/agforum/viewtopic.php?t=2334&highlight=

[K.O.]

GO  SEAHAWKS



http://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,4372.15.html?PHPSESSID=tv4hi7ojfscei7l6qbv5ga2en0

http://www.crosman-air-pistol-owners-forum.com/board/index.php/topic,4528.0.html

http://buddyl.com/edr/air/Crosman/chevell_build_pumper.htm

http://www.gatewaytoairguns.org/GTA/index.php?topic=37401.0

http://www.network54.com/Forum/275684/thread/1176754271/My+1377-2200


And many others

I really should work my way thru some choked flow material but to many concussions...

So  I will just see what develops by Trusting my gut

[K.O.]

the barrel:

I am thinking  that a .170 wide(so the pellet does not catch) oval port .205-210  long.   Bart is willing to make a delrin transfer port when he mods the 760 nose till it is like a 2100 nose but  .3 longer : which means  extending the cavity up into the nose,  shortening.
will drill transfer port only so deep at .210 and then blend to barrel's oval as best I can...



The valve:
I did some rough measurements (small exclusions that I think balance, left out)of the  2100 and 13xx valves with my cheap dial vernier and the calculations to me give

the 13xx .13 ci  (stock)
the 2100  .1 (stock)   ( modding poppets and the .3  added length should buy me a .136 or so valve)

I an considering just stretching the 2100  valve spring.  (needs thought)

would really rather sleeve the back of the 2100 tube so I could hog out the  13xx valve and use it cause I think the .25 pellet can use the bigger charge.

In the how few threads can it  take poker game ; assuming 1500-1700 psi  would you bet (2.75)(3) or 3.25...

so far I know the 2100 hamer and spring are working.

[WyoMan]

You don't need luck, you can read the forums:
http://www.network54.com/Forum/275684/message/1389216993/Think+of+it+in+terms+of+pressure+differential...
http://www.network54.com/Forum/275684/message/1389244410/If+you+want+a+deeper+understanding...
http://www.network54.com/Forum/275684/message/1358401495/Pressure+%2A+Volume+Energy%85%85..
http://www.network54.com/Forum/275684/thread/1374886480/One+way+to+not+pump+so+much
http://www.network54.com/Forum/275684/thread/1150373061/Modded+1322+results-+All+shots+are+from+empty%2C

I think you understand pressure*volume energy but you need to build the power plant to get the most benefit...build a high pressure pump first, more volume is easy and will be the icing on the cake if you can develop high pressure. Note that pressure means closing force on the forearm...with the right build that can be over 40lb with the 10th pump (sea-level pumps).
http://www.network54.com/Forum/275684/thread/1373506150/1322+is+still+my+favorite......long+with+lots+of+pics
No need to pump more than 10 -15 times unless you're doing an AC setup (pcp with the on-board pump)

Would also help to get a real Chrony to have real results...hth

[K.O.]

You don't need luck, you can read the forums:
http://www.network54.com/Forum/275684/message/1389216993/Think+of+it+in+terms+of+pressure+differential...
http://www.network54.com/Forum/275684/message/1389244410/If+you+want+a+deeper+understanding...
http://www.network54.com/Forum/275684/message/1358401495/Pressure+%2A+Volume+Energy%85%85..
http://www.network54.com/Forum/275684/thread/1374886480/One+way+to+not+pump+so+much
http://www.network54.com/Forum/275684/thread/1150373061/Modded+1322+results-+All+shots+are+from+empty%2C

Thanks  will read tonight  and thanks to you also Ed your post about yours is amoung those post that helped me figure this project out to the point of being willing to try to build what was my goal when I started


I think you understand pressure*volume energy but you need to build the power plant to get the most benefit...build a high pressure pump first, more volume is easy and will be the icing on the cake if you can develop high pressure. Note that pressure means closing force on the forearm...with the right build that can be over 40lb with the 10th pump (sea-level pumps).
http://www.network54.com/Forum/275684/thread/1373506150/1322+is+still+my+favorite......long+with+lots+of+pics
No need to pump more than 10 -15 times unless you're doing an AC setup (pcp with the on-board pump)

Would also help to get a real Chrony to have real results...hth

[K.O.]

"Would also help to get a real Chrony to have real results..."

How inaccurate do you think the sound card method is...?



"I think you understand pressure*volume energy but you need to build the power plant to get the most benefit...build a high pressure pump first, more volume is easy and will be the icing on the cake if you can develop high pressure. Note that pressure means closing force on the forearm...with the right build that can be over 40lb with the 10th pump (sea-level pumps).
http://www.network54.com/Forum/275684/thread/1373506150/1322+is+still+my+favorite......long+with+lots+of+pics"

I have not read the links yet

I did wonder in the other thread if the stuffed plastic piston and fitted cup will make it to 1500- 1700 psi...
one good thing about moving the intake poppet up into the nose is a touch less head space.
I would like to stick with a cup BUT

I in a while may try to tackle an adjustable piston that is both cupped and has a  oil control o- ring



I was thinking of the option of a three piece valve with a thick wall center section for plumbing a caged(durability) co² cart. on the 3 shot conserver type...

[K.O.]

thanks guys for the encouragement...

I have almost am certain I will pass 490 and will be embarrass if it does not...

575-625 is being a bit to very optimistic.    I think, but just may hit the low end of that.

[K.O.]

Low budget, reliable and making the most of what is there is the theme and why I am willing to pump a bit more rather than going high pressure.

when I dreamed this up 625 fps was the goal.

seeing as this is just my 3rd mods I figure it is easier and cheaper to go the increased volume route.


The thought of a 700-800 fps .25 pumper does hav its thrill though and I do not think it is doable without some more serious psi. $$

[HappyHunter]

575-625 is being a bit to very optimistic.    I think, but just may hit the low end of that.

"Should" be no problem.

A buddy of mine is getting 565 fps (@ 20 pumps mind you) w/20 gr H&N FTT's in his 2589 (same basic gun) with nothing more than  a FTP and heavier hammer spring. Still using stock ports too, so some room for improvement yet
http://www.airgunforum.ca/forums/topic51530.html

[K.O.]

"Should" be no problem.

A buddy of mine is getting 565 fps (@ 20 pumps mind you) w/20 gr H&N FTT's in his 2589 (same basic gun) with nothing more than  a FTP and heavier hammer spring. Still using stock ports too, so some room for improvement yet
http://www.airgunforum.ca/forums/topic51530.html

Thanks for the encouragement.

when I picked up my 13xxs and 2100 knowing very little about modding I had some goals and one of them was a .25 pumper with some decent velocity 650-700 fps with common parts.

while I still think is doable I did moderate my goal to 575-625fps after reading some.

then well my confidence fell a bit.

so I did some thinking.

I looked at it from the 2100/2200 viewpoint and with what I plan to do it would push a 2200 to about 700 fps with 14.3s and and 625 with 18.1s

18.1g  .22 and  20.1g  .25 will act very similar in the barrel with the edge going to the 20.1g until about 15" into the barrel and by then well most of

the  acceleration is done.

I used a .13 for the vale volume and 1400 psi  and then developed an index from there to check

point is that it makes 630-640  look like what I should get with everything done just right...

so I am feeling good about  achieving 625fps with 20.1g  H&N FFTs.

It also helps a lot knowing it from what mods to a 1325 to get a certain fps since what I am building is basically just a long stroke 13xx

so yep your post does help...    THANKS



IMO because of the limited valve volume what I get will be limited by what the stuffed plastic 2100 piston can handle.

I am pretty sure that it will be at least 1200 psi and the very top would be about 1700  but honestly think it will be in the 1450 range and my gut says

right around 610-630 fps

Where is the crossed fingers smiley?

[K.O.]

565 with .140 ports and stock valve volume wow does that give me HOPE...

my port will be .195-.205 ish.

I believe a big pellet needs as much of a charge as it can get to get it going...

IMO (again) with a .25 bore the parasitic losses of a big transfer port are dwarfed in the first few inches.

[K.O.]

http://www.network54.com/Forum/275684/thread/1373506150/1322+is+still+my+favorite......long+with+lots+of+pics

Wyo your 1322 is inspiriting in how well built it is.

Over time I hope to improve mine to a little closer to that level.

right now I am just getting them built to the point that they shoot straight.

I hope to get Steel breeches within the next couple months.

right now just my 1322 has one.

they all will be drilled and tapped for another grub,

and I will pin the valves very soon.

I will also get some bar and round stock and try my hand at 2 piece barrel bands.

I was going to sleeve the intake passage on my 13xx valves but I like the safety pin thing,

much simpler and acts as a guide to keep the poppet strait.

Did you notice any increase in pumping effort?

[K.O.]

Oh I also noticed that you left 4 threads on the valve.

Do you think having any less is not worth the risk?

[K.O.]

Waiting on parts and man do you keep going over your working theories...

The good news is a GTA thread that features stuffing a 2100b piston and I now know for sure it will do enough for what I plan and should even hold up

to about 20 pumps due to the increased valve volume I will have...

Starting to think just maybe with luck 1500- 1600 psi @ 15 pumps that and supposes a only slightly optimistic  70% efficiency for the pump...


http://www.gatewaytoairguns.org/GTA/index.php?topic=59823.20