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Author Topic: My latest CO2 2250 tune  (Read 343 times)

Offline Mintie

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My latest CO2 2250 tune
« on: October 04, 2018, 01:03:34 PM »
I haven't been posting much lately but be assured I am still tinkering around in the back ground.

The latest tune I did on a Crosman 2250 needed to be powerful but efficient and short. I have left it running the standard length barrel and running on the 12g cartridges for simplicity and less weight. Below is the list of mods.

Polished hammer
HST adjuster - Made with a big enough thread to swap hammer springs out without having to strip it down
Custom CF silencer
Valve head bored out, TP opened up to 4.5mm and angled towards the seat
Valve cap threads cut off, bored out, and deepened to reduce VST and increase volume
Valve pin reshaped slightly to help encourage flow - Don't take too much off the brass or they fall apart!
Hammer and valve spring ends polished
Barrel TP opened up to 4.5mm
Custom rubber tube TP with 5mm ID
Steel breech
Polished trigger sear and custom spring tension adjuster
Take down spring button to add and remove the stock with the push of a button

This particular rifle has already sold but the results have encouraged me to build up another one with similar mods which might motivate me to finally get into building a custom stock.

The end result was a short, quiet and very lightweight rifle shooting at a very consistent 13fpe for 17 shots before they started to drop off in power. I think that's a good result and the fact you can just carry a couple of spare CO2 cartridges in your pocket as a back up makes it a great alternative to PCP. IMO 13fpe is plenty of energy for Rabbits and most birds out to 40m once you know what the trajectory looks like.

This shot string was done with 16gr JSB pellets, I was pausing for 30 seconds between shots but my hand was holding the tube which was heating it up slightly - that explains the slight lift in power. If I had just been shooting on a bench and left it longer between shots I think it would have been even better. This still beats un-regged PCP's, and probably beats some regged ones too!

My next build will be aiming for similar or slightly more power, it will include a new 3D printed magazine that attaches to the breech from a chap in the UK and I have a new idea for increasing the valve volume quite a bit so it will be interesting to see what that will do.

Nova - I suggest using something like a 2250, Diana (not actually Diana made) Chaser, CP1 or a QB to base your CO2 experiments on. All can be imported for a fairly reasonable price if you cant find one second hand.





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Offline Dvlnme

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Re: My latest CO2 2250 tune
« Reply #1 on: October 05, 2018, 07:30:04 PM »
good to see some one still modding the 2250/2240s,they lot fun to build,sounds like you got that one dailed in pretty good.
 cheers mike

Offline Mintie

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Re: My latest CO2 2250 tune
« Reply #2 on: October 08, 2018, 12:01:30 PM »
Cheers Mike, I like the self regulating nature of CO2 even though it is fairly low energy compared to HPA. I think 13fpe in a small package like this is perfect for some of the orchard walking I do.
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Offline Dvlnme

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Re: My latest CO2 2250 tune
« Reply #3 on: October 08, 2018, 08:20:52 PM »
i still got soft spot for co2 myself,specially with 12fpe or less 177 cal rifles,which i like to make my own
 compact co2 cylanders for,if was me biulding a 2240/2250 these days i would extend tube with screw in
 extention to allmost full barrel lenth,simialler to the hipac hpa units,i hate the bulk fill units some make
 with 9oz paintball bottles or with remote co2 lines etc.not only are these big/bulky/heavy etc but bloody
 ugly to look at and i am very fussy bout those things on my guns,cant see the point in spending all the
 time on any gun if dosnt balance n handle well too,but each to their own i guess eh!!liked how your 2250
 came out,13fpe dosnt sound much,but its plenty for rabbits/possums out to 25/30 meters if you put pellets
 in right place eh!!i shot heaps possums in fruit trees with only 8/9 fpe in 177 cal with my bulk filled gamo
 co2 extreme rifle. much as i love my powerfull pcps,i have no hesitation using the gamo either if distances
 are short around 12/15 meters which is usual in fruit trees a little 7.5 grain pellet in the noggin puts em
 down quite easily.
 your little carbine be nice easy carrying for evening walkys mate.
 cheers mike

Offline FLUB

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Re: My latest CO2 2250 tune
« Reply #4 on: October 21, 2018, 09:20:57 PM »
That's really good shot to shot consistency and I see the 13fpe as a bonus. My 2250 is 10.50fpe with nothing changed except fitting a LH breach, 24" barrel and your  carbon over-the-barrel suppressor. Next strip I'll work on the valve, polish the trigger and fit a stronger hammer spring. No need for any power adjustment as I'm happy to run full power always as I only shoot bunnies in my own paddock and prefer to learn the rifle characteristics.

My LH Hammerli 850 with custom walnut stock is still my favourite rifle, but the 2250 has grown on me as it's so easy and quick to handle. Dvlneme has a good idea about extending the cylinder to ssomehow fit more gas. I have an adapter for my 850 that takes 2 x 12g cartridges instead of the 80g cartridge. I'll have a look to see if that's a possibility. Although I think the 2250 is self piercing on the first shot, so won't be able to keep the gas valve open.

Offline Mintie

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Re: My latest CO2 2250 tune
« Reply #5 on: October 22, 2018, 08:15:44 AM »
Extending the amount of co2 on board a 2250 isnt easy without it looking and feeling cumbersome but I have a cunning plan for my next build in .25! Stay tuned
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Offline Dvlnme

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Re: My latest CO2 2250 tune
« Reply #6 on: October 22, 2018, 10:15:21 AM »
i would go to bulk fill and use the same screw in bulk fill units i made up for my gamo g1200 rifle,these just
 screw into end cap threads and are intercgangable with end cap.so can use both 12 gr disposables and
 bulk fill units,with no modes needed to tube, the one i made for the g1200 holds 36 gr co2,very light
 weight be made alloy,bout 6 inchs long and one inch 2024 t3 tubing,fill valve in the front,with qiuck snap
 fitting,and works very well,allso tryed it on hpa at 1100 psi just out curriosty,got 10 good shots from 1100
 down to 800psi as per follows.580/591.4/574.4/571.1/570.5/545.8/550.8/538.6/535.4/531.6. for average
 of558.9,extreme spread of48.5 fps over 10 shots.averge fpe went up slightly to 5.2fpe from 4.8fpe on co2.
 upshot being now going to make a decadicated regulated hpa cylander,reg set to 950/1000psi,with 3000psi
 fill pressure that will interchange with 12gr disposables/36gr bulk fill cylander/reged hpa cylander,just for
 the hell of it as this will give me bassiacally a reged pcp unit for rifle as well the co2 options,as have
 allready done for a gamo co2 extreme rifle,this rifle on hpa gives 11.5fpe up from 8.5fpe on co2.no
 modds were made to either rifle valves etc.
 did post some pics while back i think of these co2/hpa cylanders,prob in mod thread some where.
 good way to do bulk fill n hpa conversions without modifying the guns,and can still use disposable co2 etc
 as most will kno i cant post pics myself,so usually have wingman doso for me any one wants some pics
 how i made these will have ask him to put some up if i send them to him first but his such nice guy he
 noramally doso for me.
 cheers mike

Offline Dvlnme

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Re: My latest CO2 2250 tune
« Reply #7 on: October 22, 2018, 04:20:48 PM »
tho pcp guns are by far my preferred airguns,i do still have a soft spot for certain co2 airguns,the 2240/
 2250 being some those guns,tho i now prefere the cpi as a platform to build hi performance co2 guns on,
 a well set up 2240 will give approx 16/17 shots at a round 12/13 fpe in 22 cal which even tho i buy co2
 12gr disposables in bulk 100 at time for approx $1,50 each makes for rather expensive shooting at $8,8
 cents a shot plus pellets etc. on bulk fill i get 416 12gr equivelent per 5kgs co2,as i get my bulk co2 for
 free in the form of out date co2 fire extingishers,normally my costs are nil,but god forbid i ever have to
 have a 5kg extinisher tested n refilled the cost is $80/100,i get 16,000 shots at 40 shots equivelent per 12
 gr from most my guns,even at 17 shots per 12 gr eqiuvlent that works out at 24cents per 12gr of co2,as i
 fire approx 4000 shots a year thru the co2 guns on average,thats 4 years of co2 from one 5kg cylander
 at 40 shots per 12gr co2,at 17 shots per 12gr of co2 that works out at over 7000 shots per 5kg of co2.
 evan paying for the co2 at $ per 5kg thats 23 cents per 12gr co2,a huge difference from $ 1.50 min for a
 12gr disposable,cost me $ 150 to set up for bulk filling,thats a one of cost,just like setting up for a pcp
 fill station,and very soon pays for its self,the bonus being i never run out co2 for years even if i never
 get another free co2 extingisher,but as have more than can ever use now thats never guna happen eh!!
 so am very keen on setting up all my co2 guns on bulk fill, and believe me i will allways figure out how to
 bulk fill any co2 gun that i like enuf to own,bulk filling co2 guns a bit a thing with me,but am not into
 slapping huge 9oz co2 bottles onto my guns,coz they big ,heavy n just plain ugly to me,and not  really
 necessery either,so i never modify any gun from how it looks in factory trim,i hate those qb78s with
 bloody great big 9 oz bottles hanging off them and others like them too,to me nothing looks as rediculous
 as a lovely old crosman mk 1/2 pistol with 9 oz bottle hanging off the pistol grip as many seem do today
 bulk filling a co2 2240 pistol nicely isnt hard,dosnt need complete new longer co2 cylander.a nice compact
 screw in extention looks much better and works just fine too,36cc plenty co2 plenty for a pistol and gives
 50 shots at 17 shots per 12gr equivelent in nice looking and handling pistol, or carbine,no exposed hoses
 or large co2 bottles,just a nice gun with decent shot count.
 cheers mike

Offline Mintie

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Re: My latest CO2 2250 tune
« Reply #8 on: October 24, 2018, 10:11:56 AM »
Started writing up about my next build using more co2 capacity but decided to write it all up in a new thread to follow the next build - Pics up there of the bigger co2 vessels and my basic plans.
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