My 2240 progress so far, not where I thought I would be

[mameman23]

Looking for some thoughts on if my assumption of where I would be is off. I figured I should be seeing higher fps.

Progress so far.

10.1 crosman barrel
Alchemy longer .22 probe
Alchemy boss rp valve
Alchemy stronger hammer spring
Alchemy big port
Steel breech
Tko 6.5 moderator
Adjustable sear spring
Alchemy Roller trigger

Ran it on the chrono tonight, indoors.
Time between shots, just reload time.
Temp:68 °F
BP: 29.55 inHG
Shots
#     FPS        FT-LBS     PF
20    419        0.00       0.00     
19    426        0.00       0.00     
18    426        0.00       0.00     
17    432        0.00       0.00     
16    437        0.00       0.00     
15    441        0.00       0.00     
14    446        0.00       0.00     
13    446        0.00       0.00     
12    448        0.00       0.00     
11    452        0.00       0.00     
10    457        0.00       0.00     
9     459        0.00       0.00     
8     460        0.00       0.00     
7     467        0.00       0.00     
6     482        0.00       0.00     
5     479        0.00       0.00     
4     482        0.00       0.00     
3     485        0.00       0.00     
2     483        0.00       0.00     
1     495        0.00       0.00     
Average: 456.10
StdDev: 22.63
Min: 419
Max: 495
Spread: 76
True MV: 456.10

[nervoustrigger]

What is the weight of the pellets you are shooting over the chronograph?

Is the barrel port opened up to about 0.170"?

[mameman23]

What is the weight of the pellets you are shooting over the chronograph?

Is the barrel port opened up to about 0.170"?

Ops you are correct missed that bit. Crosman premier 14.3
Port is the alchemy one that was paired with the valve "BOSS BUDDY" High Flow Transfer Port" looks big

[nervoustrigger]

I got that...big exhaust port in the valve, big transfer port

What about the port in the barrel itself?  That could be what's choking it off.

[mameman23]

I got that...big exhaust port in the valve, big transfer port

What about the port in the barrel itself?  That could be what's choking it off.

Ahh, yes barrel port is still stock, that said it did not look to be blocking the value port any when I assembled it.

In hindsite, this maybe an issue, I will check and open up if needed tomorrow. Thanks.
More to come 

[arkmaker †]

Do you have a Power Adjuster on it? Believe it or not, sometimes to much pressure on the striker can lead to a waste of gas and for some reason lower fps at the start and the quick loss of power and shot count. That what your string looks like to me. Try using the stock spring if you don;t have a PA and see what you set.

I got these strings with a stock valve, spring and PA with a 10" .22 barrel shooting the 14.3's. The only things adjusted were the turns in and out. Settled on the Red string.

[nervoustrigger]

Regarding the barrel port, I could not find the diameter it has from the factory but I looked back at the 2240 barrel I swapped out last year and I had apparently drilled it out to 0.154" (#23 drill).  I want to say it was originally 0.140", same as the stock transfer port. 

So assuming the Alchemy exhaust and transfer port are at least 0.170", you should see a nice gain by enlarging the barrel port to 0.170".  If you go much larger, pellets may get chewed up when being chambered.  Of course be sure to deburr the inside of the hole.

To put it into perspective, going from 0.140" to 0.170" is a 50% increase in area.  That is significant when looking for higher energy.

[mameman23]

thanks guys, i did indeed find the barrel port was smaller naturally than the boss transfer port. so i opened it up to match the transfer port circa .170. so far it has not made a difference with fps in testing.

I had the thought around the hammer spring also and put the stock one back in, made zero difference oddly.

a power adjuster is on the list to get to fine tune it, just finding it odd these changes made little difference. I would have expected the barrel opening up would have seen a change.

Unless the extended bolt is coming into play here as there is alot of it sitting across that barrel hole.

I was wondering on the additional co2 and 10" barrel. was reading last night that based on timing and the additional volume it may need a longer barrel since the pellet is out before its all done dumping.

Frustrating as I  have a bone stock 2240 sitting here doing the same basic numbers 

[nervoustrigger]

Sounds like you are about to find the culprit, if you haven't already done so in the bolt probe. 

For there to have been no difference from enlarging the barrel port, something else is restricting flow.  Like you said, it could be the bolt probe.  I just pulled up a picture of it on Alchemy's site and it does look pretty chunky.  I would turn down the nose to about 0.060" for most of its length, and do a radius blend up to the shoulder for the O-ring.  This picture is of a .177 bolt but it should give you an idea.


Or it could be a misalignment in the valve exhaust, transfer port, and barrel port.  In an ideal world, all 3 would be perfectly concentric.  The Crosman transfer port, with a shoulder on both sides, helps ensure they are aligned.  Based on the picture of the Alchemy transfer port, it looks like it is designed to work in a similar way.  Maybe you can look at it carefully and see how it fits to both the valve and the barrel and see if that is a source of the restriction.

FYI, I considered the possibility of blow by from a leaky transfer port but if that were the case, there still should have been some improvement in velocity when you enlarged the barrel port.  The only counter argument for that I could come up with is that the alignment could have possibly been worse when you reassembled, thus no improvement was seen.  That seems pretty unlikely but I just wanted to mention it for the sake of completeness.  Best not to leave any stone unturned when troubleshooting.

Regarding barrel length, you can certainly expect better performance if you go with a longer one.  The fact you lost no velocity with the stock hammer spring suggests the valve is staying open longer than necessary.  Using the heavier spring will simply harm shot count and make a louder bang when you pull the trigger.

[mameman23]

Thanks, I also pinged David @ alchemy and he confirmed also my thoughts on the performance valve and barrel length. So i am going to have a little play with what you have suggested while i also wait on a longer barrel. I have another 2240 in the works so nothing goes to waste

I also feared the alignment issue with the ports but was pretty anal when putting it together so i think we are good there. no harm in taking it apart and trying again either.

Thanks for all the steers, will see what happens next and report back.

fun stuff.

thanks again.

[nervoustrigger]

No problem, I hope you get it sorted out soon.  It's also good to hear you're having fun with it.

[BillK]

Do you have an over travel screw on the grip frame?  Sometimes if the screw is too far in it will cause the hammer to drag on the sear.  Just a thought.....

[mameman23]

Do you have an over travel screw on the grip frame?  Sometimes if the screw is too far in it will cause the hammer to drag on the sear.  Just a thought.....

Don't think I do. Is there usually one on a 2240?

[BillK]

Usually a completely stock 2240 does not have an over travel screw.  Not knowing all the mods, I thought I should ask.
It is the screw that prevents the trigger from any more travel after the sear has been tripped.

[mameman23]

Usually a completely stock 2240 does not have an over travel screw.  Not knowing all the mods, I thought I should ask.
It is the screw that prevents the trigger from any more travel after the sear has been tripped.

Ahh, ok.no Have not fitted one.