2260 cothran pcp

[Laz]

Hey folks, I'm wanting to build a 2240 up with the cothran 2260 pcp tube and the works. What I'm wondering is, this will be in .177 cal, can a regulator benefit such a build or is the tube too small for a real impact? Anyone do this with the .177 and 2260 pcp tube before? No bottle, just the cothran 2260 pcp tube.

Any info or insight greatly appreciated. Just getting back I to airguns and I'm set on building a cothran 2260 pcp from a 2240, just looking for insight, opinions and info.

Perhaps a cothran 2250 pcp carbine in the mix down the road as well...

Thanks

[Monkeydad1969]

I built my Cothran .25 with the 2260 tube and his valve.  I first used a Disco valve I opened up, but to be honest, you may want to ask him to do a Disco length tube.  He quoted me a price, I don't remember exactly---but it was about a hundred shipped.  That was over a year and half ago.  You could regulate it, but are you wanting consistency of shot count or a flatter line for power?

Joe

[Gerard]

A well made and appropriately tuned SSG will give you a higher shot count for two reasons; less air wasted by preventing hammer bounce, and more tube available for high pressure air because no regulator/plenum taking up volume. Read the SSG thread and either build one or have one built for you.

[rsterne]

Unless you are building a very low power setup, I think a 2260 tube is too small to be useful with a regulator inside it....

Bob

[Ribbonstone]

IF it's a standard full 2260 tube length, would likely come out a little larger than a P-Rod's volume...they sell a lot of P-Rods/ 1720's.  With no end caps, not the volume area, just the length of the whole tube, the 2260 is about 1" longer...considering the "guts" that go into the tubes, likely the volume would be pretty close.

Do agree that high power and small air volume are not going to make for long shot counts.  BUT there are many times while moving/stalking/walking though the woods  for an hour or two, where 12-20 shots would certainly "do it" (and only that many if I got side tracked by a cow-pie that needed splattering or an eating-sized bullfrog).

[rsterne]

The 2260 tube has a volume of only 65cc.... I use one for my Grouse Gun, and get 16 shots at 20 FPE from a 2000 psi fill.... However, subtract the volume of a regulator and the plenum required for that amount of power, and the reservoir would be about half that.... Reduce the power, and hence the setpoint pressure, and the volume of plenum required, and it might be worth it.... That was the point of my comment above.... Doing a .177, and filling to 3000 psi would help shot count a lot, of course....

Bob

[Laz]

Thanks everyone for the replies and information.

I'm looking to build it in .177 for a potentially higher shot count as a close to medium range small game shooter (e.g. up to 40ish) and will look into the SSG thread.

Joe- I'm thinking now with all the info that a flatter line with decent power for the tube size is more desirable to me than a lower powered regulated gun.

[Monkeydad1969]

Hey Laz,

Looking forward to your build.  I plan on doing a new .177 build, too.  So we should compare notes thru a PM.

Joe

[Ribbonstone]

LEt me see....what airguns do I have with less than 80cc's of volume?

2260 HiPac (old version is a little bigger)  = 75cc's



.177 / 2260 HiPac (newer version is a little smaller) = 72cc's



.22 Power Max pistol (REGULATED)  = 68cc's



.22 P-rod = 65cc's



.177 QB78 HiPAc = 54-55cc's



.177 1701 Crosman =  45-46cc's



.177 2300 HiPAc pistol = 30-32cc's



(Can add in another  4 rifles under 140cc's)

Evidently I've found a use for the small air volumes when hunting, but generally limit the power output to whatever I can get with about 12-16 shots per fill (with good efficency).

Hunting is different from target shooting, plinking, varminting, or metal-critter-games.  So long as you don't get side tracke3d by splattering cow-pies, shooting knot-holes, or generally goofing around, are NOT likely to get 12 good clean shots an afternoon.

So I am interrested in the short (2260) length PCP tube...been thinking about it...have an old RJ riser breech, a crosman sized 5mm 12" barrel,  the guts/machining for a shroud, valve, and complete trigger housing.  Figure a new PCP tube and a few valve retaining screws, and I'd be good to go.

[Laz]

Those are all fine looking guns Ribbonstone, I've been reading that the powermax guy is getting back into business, I can see a hipac carbine in the future.

And Joe, that sounds good. I ran into a speed bump as I found a really good deal on a 2240 with stock, steel breech, and 14" bbl for a $130 CAD, but was sold before my pay day  that would've helped in terms of getting all that for cheap so gotta either wait for another good deal or start from brand new which isn't bad, was planning on new tube and breech with eventually trigger, bbl and stock set up anyways. Pm's will be sent along the way.

[Laz]

Well 2240, co2 and cphp pellets came in   

Let the fun begin.

Shooting it is hard. I've only ever shot rifles and I am not used to the sights    scope, steel or aluminum breech and the crosman shoulder stock are definitely next.

In the mean time will continue shooting and have fun. Am going to do what I can to the trigger tonight and clean it up where necessary.

22xx PCP here I come

Anything anyone can recommend that I can do to this stock pistol without any aftermarket/custom parts?

[Gerard]

Well with just your work, nothing purchased, probably the best modifications revolve around the hammer. Grinding away excess steel, getting its weight down to 50 grams or less (2oz), then adding whatever sort of shim to the spring to increase initial velocity of the hammer, these changes would give you a flatter velocity string with better efficiency. More shots hitting the same spot. All you need is a grinder and a bit of caution to avoid grinding the wrong places. The hammers in these airguns are too heavy, too much gas gets wasted after the pellet is gone. Same applies to most production airguns frankly. A lighter hammer moving faster will improve things. And if you ruin it a replacement hammer is cheap enough.

[Laz]

Thank you for the information and tips Gerard. I did the trigger spring trick and stretched it out some as well as polished he contact points on the trigger/sear. My brother got a 2240 same time as me and today shooting, my trigger was noticeably lighter and smoother. I'd like a bit lighter and smoother but will just break it in more until I can cough up the coin for an aftermarket trigger. Got some washers today at the hardware store to try to shim the sear and trigger. Hopefully one works, as the play in the trigger is quite noticeable.

Really looking forward to getting this set up with a Cothran 2260 pcp tube...

Not sure if I want to get a BNM breech for multi shot or save money for the next project/gun and get an aluminum breech from baker airguns. Too many options.

[Gerard]

It is tricky shimming the trigger as too much will bind it and there really isn't a lot of space, so a spring washer is probably best. I bought a machined aluminum side plate by DerekVinyard, really brought a significant amount of control into that area. Then I tried various trigger fixes until finally settling on this one. It's an extension of a mod I found on the Yellow, just a couple of steel rods soldered into holes bored into trigger and sear. The trigger pin is a nail, the head filed narrow so it doesn't rub on the sides. The search pin is the shank of a small drill. Had to soften the front end of the sear first as that is tempered rather too hard to drill. The result is dramatically increased leverage, resulting in a very light trigger with a short pull.



Polishing parts can only get you so far. Modding can be fussy, even frustrating, but can be so worthwhile when it works out. I've just reminded myself... got to do this on my QB78D as well. That carbine uses a 22xx grip frame, trigger and sear, so of course I should make the trigger smoother there, even though it's already easier than stock. I like my triggers to be between 1lb and 2lb, no heavier.

[25ACP]

Nice trigger Gerald. Would you have a photo of your modified hammer by chance?

[Gerard]

This is the hammer for my 2240, weight reduced to 48 grams:



And this is the hammer in my QB78D, weight reduced to 38 grams with nylon guides added

[aluminumfetish]

How did you remove material from the hardened hammer ?

[Gerard]

With a Dremel and a grinding bit on the 2240 hammer, then a sanding drum bit, then sandpaper on a stick. On the QB78 hammer I used a Dremel grinding burr but with the hammer mounted on my small lathe for most of it, also boring out the middle with a carbide bit to allow a slightly larger OD spring. The flats I ground on my bench grinder.

[25ACP]

Thank you Gerard, now it even looks like a "hammer"  I bet that took a while with a Dremal, but it looks very good!