.25 Caliber - what base model?

[NorthStaR]

Having slept on the thought I'm still undecided on the whole PCP or bulk fill aspect.   

I just don't dig HPA and Co2 bulk fill isn't really an option for me at the mo...

I have always favoured the 12g capsules as a personal choice. Cheap, simple and safer. I suppose due to power limits
it seems like I'd be using something far too restricted for it's potential. It's like having a ferrari and only being allowed to use first gear.

12g capsule - same 850psi scenario but less of it, professionally filled and less to worry about. Perfect!

Also I can keep all my guns (relative to Co2) running on the same source of gas if they all accept the same input device.
I'd rather my gun do the barrel fart than have a part of it fly off, kill me and enter the wall.

No country for old men? No guns for dead men!

It may end up weaker than the Stateside setups but it will be truly silent except for the thud of a .25 hitting home. 

Exciting stuff! It should arrive this weekend if I'm lucky. Do I feel lucky...punk?

[gdm620]

I've been watching Ted's Holdover Youtube channel lately. He uses a Edgun Matador on his farm and regularly takes birds at 80-100 yards. Really impressive to watch someone hit something that far away through a scope.

That Guy can shoot    I watched several of his videos.  He is good at presenting the content on his videos.

[Cross Pistol Packer]

If I can find another 1389 would consider .25 barrel,it would have to be short to keep below 12ftlbs power limit.
Only reason why apart from great short range ratting tool,mate of mine gave me 3000 rounds of .25 ammo he did not want.

[NorthStaR]

3000    That's a good friend!

Still waiting for the barrel. I just ordered a tin of these:

[BassManNate]

That Guy can shoot    I watched several of his videos.  He is good at presenting the content on his videos.

No kidding! His presentation is part of what makes his videos so fun to watch.

[Noah]

I do not have my own .25 caliber yet, but when I build myself one you can bet I will be using CO2.

From having shot Noah's 1325 and his 2540, the 2540 was the most powerful and had the best feel.

Carl

Yes, both have 12" barrels 

[Noah]

3000    That's a good friend!

Still waiting for the barrel. I just ordered a tin of these:

Both of my Mountain Air 1325 and 2540 guns really like those same Rhinos! I have a small supply on hand but nothing like 3000 

What they really liked were the Beeman .25 round lead balls, but I can't them anywhere any longer 

[NorthStaR]

NEW QUESTION!

If in .177 cal the optimum barrel length is 24"
If in .22 cal the optimum barrel length is 18"

If in .25 cal, what is the optimum barrel length?! 14", 16", 18"...?

My question was based on a post by Mr.007 stating that he had tried a 24" .25 barrel and it had a negative outcome.
The FPS dropped out with the accuracy. Mr.007 was using an 18" previously. Apologies if I am wrong!
http://www.crosman-air-pistol-owners-forum.com/board/index.php?topic=5988.msg61886#msg61886

The optimum barrel lengths are referenced from posts stating that they thought this to be the case.
Personally I haven't tested a lot of variations of barrel lengths enough to make any mathematical conclusions to date.
My math isn't the best even if I had! 

It's a curio question. I have a 14" waiting in the depot but for future reference and for anyone else considering
this caliber I thought it would be a worthwhile post...  ..... if an answer can be reached! 

PS: Yes I have just discovered the "Horizontal rule" button on the forum! Saves typing endless minus/hyphens! 

[woody67]

Why don't you just do one of each?

As for the 22xx...I'd probably go with a 2250, but only because I like the foregrip or whatever it's called...

[NorthStaR]

Why don't you just do one of each?

Good question!

My main 2 reasons:
1: I only have a 14" barrel on it's way so anything longer is out for now.
2: If anyone already knows the answer then I don't have to cut, crown, shoot, cut, crown....

And 3:  If I cut it past the sweet spot (which I can't as it's 14" unless it is minus or as is) then I'm back to square one!

So what is the optimum barrel length!?  I gotta know!

Part of it is for knowledge, like I said the 14" is on it's way but IF I was to order more, when in stock, then I would like to go for
the optimum length from the start. Another factor is I can have it modded for attachments + an 11 degree crown by default.

One last major factor is I pay a LOT more than you US CAPOFarians for these barrels and pretty much everything else related.
For example; I have a converted METRIC breech with SS .25 probe and a 14" .25 barrel.......... £130 or $205.92! 

That my friend is why I don't want to trial and error my way to victory this time!  I'd be a Hobo in no time!
Also it could be a reference for anyone else going into this caliber so I thought it would be helpful.

[cpu77]

Well not sure who's breech you are using but a .25 barrel here is $115 a repeater breech is $200.  Thats $300 my cost:)

[eric]

a lot of the airgun gurus say that 14" barrels are the optimum  length for .22  cal with co2 . not sure about  anything  else though 

[NorthStaR]

OK, a day of salvaging parts for a temp build to test the 14" barrel in .25 cal.

Metal breech, 2240 body tube, 22xx stock valve, 1389 stock. Poly tube transfer port.

There's two purposes to this temp build. One to give out the numbers.

And two; so I can tune it to UK legal levels - no higher.


19 GRN Rhinos Pellets. Brand new 12g cart.

count,velocity (FPS),power (FPE)
01, 577,14.04
02, 588,14.57
03, 578,14.12
04, 568,13.62
05, 561,13.27
06, 538,12.20
07, 551,12.83
08, 524,11.58
09, 522,11.50
10, 552,12.86

At the time I had not noticed but there was a tiny transfer port leak. It was cut slightly too short. No other mods.


Regardless - too much power for my legal limit so I dismantled it.



Put in a lighter hammer spring plus guide (lighter spring has more wobble)
and preloaded the valve spring with 1mm of poly tube.

19 GRN Rhinos Pellets. New transfer poly tube port. Brand new 12g cart.

count,velocity (FPS),power (FPE)
01, 529,11.80
02, 527,11.72
03, 510,10.97
04, 529,11.80
05, 527,11.72
06, 510,10.99
07, 521,11.47
08, 518,11.34
09, 514,11.15
10, 520,11.40

OK now I'm sub 12FPE. Uk legal... 



As there was gas left I thought I'd try a heavy pellet thinking it would be weaker.

I thought this because the lighter Rhino pellet reached this speed/power (sub 12FPE) so therfore with a heavier one would
be slower and weaker. No.



WALTHER Hunter Energy (DumDums) 28.4GRN

count,velocity (FPS),power (FPE)
01, 482,14.64
02, 471,14.02
03, 475,14.24
04, 461,13.42
05, 486,14.92
06, 455,13.03
07, 443,12.35
08, 423,11.30
09, 416,10.92
10, 428,11.57



I didn't expect this. BTW this last shot string was not a new cart but left over from the Rhinos test so not quite a controlled test.
However this does mean I have to reduce the power further to be legal with this heavier pellet so the carbine is now disassembled
to loose parts again.

With the lighter hammer spring and preloaded valve spring it can get to a point that it struggles to pierce the 12g cart.

I'm going to ProTop and reduce the valve volume. More control and options.

All these strings were done by shot after shot with no pause.

The slight raise in power maybe when a slight pause occurred when I fumbled a couple of pellets! 

These .25 cal pack a punch! .22 is more efficient than .177  - .25 blows them both away IMHO.

DISCLAIMER: AS SAID THE OVER POWERED CARBINE WAS DISMANTLED TO LOOSE SPARE PARTS
DUE TO LEVELS REACHED. ONLY UK LEGAL LEVELS ARE MY AIM - NOTHING MORE. ABSOLUTE.
CHRONY TESTS ARE REQUIRED TO REACH THE CORRECT LEVEL. THIS IS A BASE LINE TO WORK FROM. 

[NorthStaR]

One extra string to show variation of 12g cart on .25 cal.

No valve spring preload, lighter hammer spring, poly transfer port.
19 GRN Rhinos Pellets. New transfer poly tube port. Brand new 12g cart.

count,velocity (FPS),power (FPE)
01, 502,10.63
02, 550,12.76
03, 531,11.88
04, 542,12.41
05, 532,11.94
06, 540,12.31
07, 564,13.44
08, 564,13.40
09, 559,13.19
10, 545,12.55
11, 526,11.67
12, 554,12.97
13, 540,12.29
14, 544,12.51
15, 553,12.90
16, 553,12.88
17, 527,11.72
18, 511,11.02
19, 489,10.08
20, 475,9.52
21, 485,9.92
22, 476,9.57
23, 383,6.18
24, 439,8.12
25, 376,5.98
26, 370,5.77
27, 368,5.70
28, 363,5.56
29, 347,5.07
30, 348,5.10
STOP.


BTW It is winter and not optimum shooting temps, even indoors!

[Noah]

Awesome and totally informative - thanks for the research findings.