2289 backpacker - What the heck?

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razpizdiay · #1 Post by **razpizdiay** » Mon Oct 10, 2005 8:47 pm

hey guys,

i got a backpacker on thursday and went camping for the weekend. had my trusty 2240/50 rifle with me, and backacker along with some parts for it. the backpacker, out of the box chronoed at 400fps, i am pretty pissed i tell you, but since i expected velocities of 440 from it, its not that bad. but what shocked me was this: when i put a 24" .177 barrel onto it, guess what was the velocity? 480fps with a 7.9gr crosman domed !!! technically it should have been 400 (stock gun) + 100 (barrel length difference) + 100 (.22 to .177 conversion) = 600fps

whats up with that? my only guess would be that since the barrel is long and small caliber, its choking the gun alot and that bleeder hole is detuning it not by ~50fps but by 100fps or more.

would anyone be kind enough to explain how i can get the valve out of the backpacker tube? the back end has a "dimple" in it so the valve cannot be taken out from the back, and the front is blocked by the pump, and i dont really know how to dissassemble the pump - anyone have instructions / guide?

also, what do you guys think is a better gun for me to make:
- backpacker, in original .22 but with no stock and the barrel cut and crowned so its flush with the pump tube (i think than it will be around 10inches)

- backpacker, in .177, with a 24" barrel, stock, scope, blah, blah, blah...

personally, i think that since i got such horrible results from it right now (with .177) i think that i should just mod the port, fill the bleeder hole and make myself a nice 450-500fps pump pistol rather than a rifle that only shoots at 600, anyone agrees? disagrees?

thank you,
razpizdiay

#2 Post by **sniper** » Mon Oct 10, 2005 9:27 pm

Yes, mod the port is a must on any of 22xx, you'll be shock it could do, after when you got it down path with mod the port that you can use aluminum tubing instead of poly tubing as I started at the begining without even changing hammer spring on 2240 with 14.5" barrel you get as high as 595 with nothing else modify, so you can imagine when everything else is modify .......it's a big blast .......

razpizdiay · #3 Post by **razpizdiay** » Mon Oct 10, 2005 9:43 pm

yeah,

i know about the transfer port, as soon as i get a chance to i will buy some surgical tubing, or maybe even skip to aluminum right away

but what about the bleed hole in the valve? how do i get the valve out? what are the steps needed for dissassembly of the pump?

thanks,
razpizdiay

airgunfun · #4 Post by **airgunfun** » Mon Oct 10, 2005 9:46 pm

surgical tubing???

uhhhh.....not the way to go....

#5 Post by **sniper** » Mon Oct 10, 2005 10:44 pm

airgunfun wrote:surgical tubing???

uhhhh.....not the way to go....

Yup, Rob is right, no surgical tubing, CT poly tubing, I haven't seen anything better than that for easy to use.

TCooper · #6 Post by **TCooper** » Mon Oct 10, 2005 10:57 pm

"CT poly tubing" .... is this the same as clear fish bubbler tubing?

Several years ago there was a guy on the forums who claimed that 1/8" tapered brass pressure fittings were best for the 2240 port. CanTire has them in packages of 5. I think the guy also tried the 3/16" fitting with good results but some port enlarging was necessary. Apparently the fittings should be changed if the pistol is disassembled... one assembly per fitting.

Thanks,
Todd

#7 Post by **sniper** » Mon Oct 10, 2005 11:33 pm

TCooper wrote:"CT poly tubing" .... is this the same as clear fish bubbler tubing?

Several years ago there was a guy on the forums who claimed that 1/8" tapered brass pressure fittings were best for the 2240 port. CanTire has them in packages of 5. I think the guy also tried the 3/16" fitting with good results but some port enlarging was necessary. Apparently the fittings should be changed if the pistol is disassembled... one assembly per fitting.

Thanks,
Todd

may be if it's look like the pic's.
I did try brass and other, brass is to hard to work on and more precision is needed, not as much when using aluminum but precision cut is a must. This is where you will enjoy to be an expert modding the port. Also you can only dump so much CO2 where it reaches the max, then you need to go for the barrel to increase more. So it's better try to mod the port to the max and get the highest performance without changing any spring for dumping more CO2. Therefore you will get the highest shot count out of 12gr. powerlet.

jezX · #8 Post by **jezX** » Tue Oct 11, 2005 9:56 am

where is the bleeder hole in the 2289 . i have one and there is no bleeder hole. i'm pretty sure the valve was never built to have one .the pump is to short to need any ristriction .
also 1/4 '' copper tube works good for ports and can be cut with a pipe cutter to make sure its flat on the ends . the inside needs to be flared after cutting .

airgunfun · #9 Post by **airgunfun** » Tue Oct 11, 2005 10:05 am

jezX wrote: also 1/4 '' copper tube works good for ports and can be cut with a pipe cutter to make sure its flat on the ends . the inside needs to be flared after cutting .

Using copper or aluminum is not worth the hassle in my opinion, poly tube is somewhat ghetto but it does work well.

#10 Post by **sniper** » Tue Oct 11, 2005 10:26 am

airgunfun wrote:
jezX wrote: also 1/4 '' copper tube works good for ports and can be cut with a pipe cutter to make sure its flat on the ends . the inside needs to be flared after cutting .
Using copper or aluminum is not worth the hassle in my opinion, poly tube is somewhat ghetto but it does work well.

Copper, now that's something I haven't try, perhaps it's good idea but what about oxidation ?, those green stuffs ......

Well the way I see it for fast quick job that can't go wrong poly tubing is the best, especially for first timer. For pro-job, time consuming and perfection is needed and like the extra 35+ in velocity then aluminum is the answear.

I spent 2-3 days tuning out this experimental piece on chrono for every steps that I changed, used lots of co2 & pellets, and come up with the max 595 with STOCK2240 hammer spring and NO change to the valve, it's all in the porting with aluminum. I know it isn't much but the satisfaction to get so many shots out of it as of stock spec. amount.

TCooper · #11 Post by **TCooper** » Tue Oct 11, 2005 11:55 am

Hi Sniper,

"...come up with the max 595 with STOCK2240 hammer spring..."

What barrel length?
What ambient temperature?
What pellet?
How many shots per powerlet?

The use of the aluminum sounds like a good idea. The 1/8" brass pressure fitting that I mentioned apparently does not require any special work to fit. The fitting is a small barrel shaped brass piece with tapers at both ends. It joins the breech hole and barrel hole with a tight metal-to-metal compression fit. The tapers slip into the holes. For the larger size 3/16" fitting the ports are slightly enlarged but the brass fitting is left untouched. As I mentioned, this idea is not mine and I have not tried it and I do not promote the idea because I have no first hand knowledge. The idea came from a Cr2240 tuner from past years. He claimed max output with his idea. I dunno. It's something I may try for comparison reasons only.
I would think max velocity would be achieved from a good seal at the port and maybe some port enlargement. The CT tubing should give a good seal between metal parts but, as I mentioned, I have tested nothing in this area.

Do you ever alter the port angle? Years ago there was lots of chatter about using a Dremel to carefully angle the port to remove the 90 degree angle in the valve. Shooters claimed this increased velocity and efficiency by enhancing flow. Apparently the CO2 flows better around a gradual angle vs 90 degree. I dunno.

Thanks,
Todd

#12 Post by **webstien** » Tue Oct 11, 2005 12:06 pm

when you use poly tubing for the port, do you remove the transfer port and its seal and replace with the tubing???

My transfer port seal is busted on my 2289 and even though i drilled it wider, the metal transfer port seems very restrictive, can I replace both with some 1/4 inch poly?

airgunfun · #13 Post by **airgunfun** » Tue Oct 11, 2005 12:33 pm

Exactly.

#14 Post by **sniper** » Tue Oct 11, 2005 12:45 pm

TCooper wrote:Hi Sniper,

"...come up with the max 595 with STOCK2240 hammer spring..."

What barrel length?
What ambient temperature?
What pellet?
How many shots per powerlet?

Thanks,
Todd

Hi Todd, I just run a test and just finish ..... just for U.
OK,
Barrel length is CR 14.5"
Temp. is exactly 69.9 F near the gun.
Pellet is RWS Hobby 11.9gr.
Powerlet is the cheap Walmart eagle air 12gr. (seems has smaller diameter than other one)
total shot: 37, 15-25 seconds between shots.

result:
579.9 564.5 530.5 504.3
580.5 565.4 528.8 488.5
577.8 561.2 525.3 475.6
583.6 556.0 520.3 454.6
587.0 555.3 520.1 437.1
591.1 546.6 517.5 414.2
582.2 545.5 516.1 388.5
579.8 540.3 515.7
572.3 539.2 511.2
573.1 533.9 510.1

There you have it .... fresh right out of the chrono.
I wouldn't bother below 400 because I just check that trajectory is fell by 3/4" at 40 ft.

ok, if it's confusing the number goes from top to bottom in column

#15 Post by **sniper** » Tue Oct 11, 2005 12:56 pm

TCooper wrote:Hi Sniper,

Do you ever alter the port angle? Years ago there was lots of chatter about using a Dremel to carefully angle the port to remove the 90 degree angle in the valve. Shooters claimed this increased velocity and efficiency by enhancing flow. Apparently the CO2 flows better around a gradual angle vs 90 degree. I dunno.

Thanks,
Todd

Yes, I've done on 3 of 2250/24, and 2 on QB, The result wasn't that much noticeable, I only saw on the chrono a couple ft/s different or if any, well in theory is true CO2 flows better around gradual angle vs 90D.