GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Poorman Plinker on August 11, 2015, 10:45:53 AM
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Three different ways to increase shot count in the 2240 as posted in the Crosman PoormanPlinker Mods 2240/1377 facebook group:
You can TRIPLE YOUR SHOT COUNT if you are willing to DECREASE VELOCITY BY ONE THIRD. A test of my 2240 recently produced around an average of 426 fps for about 40 shots.
The result of capping the stem was an average of 326 fps with a shot count of over 120 shots.
The change was accomplished by simply using a portion of a 1/2 in flexible vinyl round cap (the type you might find blocking an open tube on a auto carb). The size I used was made to cap a 1/8 to 3/16 tube and I used it to cap the poppet valve stem.
Words of warning: one time the full 1/2 in cap had blocked the piercing pin from fully opening the powerlet. Also, trimming the cap down to 1/4 inch did not markedly change the performance and it still produced about 326 fps and 120 shots. It does require multiple shots to open the powerlet, maybe as many as 10.
Cutting the tip off of the cap and just using the tube had no marked effect and the gun performed as "normal" or unmodified.
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You can INCREASE SHOT COUNT BY 46% if you are willing to DECREASE VELOCITY BY 2%. A new test of my 2240 recently produced around an average of 431 fps for about 32 shots....
The result of shimming the valve head was an average of 423 fps with a shot count of 47 shots....
The change was accomplished by preloading the valve spring 0.189 inch with three nylon washers. The size I used to load the valve head was a #8, 0.173 ID, 0.375 OD, 0.063 (+/-) thickness....
Preloading with two nylon washers (0.126 in) produced a 42 shot count (31% increase) and an average 428 fps (0.7% decrease)....
The factory condition actually had velocities marginally higher than the modded valve for the first 15 shots in both comparisons. Thereafter the modded valve velocities were higher than the factory velocities. This was not so much that the modded velocity increased as it was that the factory velocity continued to decline as the other valves maintained velocity....
The three shim results graph like an upside down bathtub. The three shim valve results were near the 400 mark for the first 10 shots, the next 17 shots were closer to 440 and the last 20 shots were quickly sloping off to 400. However, the two shim results were near flat for 25 shots with only about an average 10 fpe rise on shots 3 to 20 and, of course, falling off from shot 26 to 42. The Factory valve created just a downward sloping velocity.
Words of warning: The use of a power adjuster or washers to preload the mainspring may not cause an increase in velocity, but only reduce the shot count without added velocity. Also, this added load on the valve stem may cause the seal to wear prematurely and also requires more study.
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Mr. Temples has suggested clipping off 1/4 in from the mainspring in order to increase shot count. I cut 1/4 in (3 coils, with the closed end counting as one coil) and got remarkable results. There was a 78% (25 shot) increase in shot count with a 4.2% average velocity loss (431 down to 413)....
The velocity loss was far greater than the valve spring shim results, but the count increase was around double. This was not as efficient as the double shim valve with a 31% shot increase and 0.7% velocity loss....
But what makes this mod most notable (other than the fact it is easy to do and requires no new parts) is the standard deviation of the shot string. While the factory and valve shim shot strings had SD in the high teens and low twenties, the spring clip only had a SD of 5.
8)
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Nice work..There is another somewhat simpler way to get a high shot count from a 12g powered 22xx Crosman.
You can install a Pro-Top which will allow you to manually puncture the 12g powerlet and not rely on the force of the striker spring to open the 12g. From there striker spring tension can be reduced to the lowest point that the
stem can be cracked open, which will be even lower if using a Disco stem and valve body.
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Three different ways to increase shot count in the 2240 as posted in the Crosman PoormanPlinker Mods 2240/1377 facebook group:
You can TRIPLE YOUR SHOT COUNT if you are willing to DECREASE VELOCITY BY ONE THIRD.
I totally agree with fivestar45. By the way, your post is way too long for me to read, so I had to disagree by default.
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Would reducing TP size increase shot count?
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Marginally, the big problem with a 2240 is that the valve is open too long for the short barrel.... It is still releasing CO2 after Elvis has left the building....
Bob
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I was going thru my 2300KT, I wanted to slow it down some. I have been shooting a lot of 5M targets lately and don't really need the power it has. I took out the spring guide that has a .150" boss on it with a #4 washer behind it for preload. I guess the spring has set. I'm getting a whooping 270-300FPS. That should improve my shot count.
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I am not familiar with the ProTop... but it sounds like (from what you described) it is changing the mainspring as in example 3 that is what changes the shot count and not the ProTop itself??? I will see what I can find out about the product, though I have little interest in aftermarket gadgets. 8)
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Here's a link as to what they are about. Mod please delete if this is not permitted.
http://www.network54.com/Forum/275684/message/1294522769/If+You+Have+a+Crosman+22xx+using+12g%27s+Read (http://www.network54.com/Forum/275684/message/1294522769/If+You+Have+a+Crosman+22xx+using+12g%27s+Read)
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Doesn't some of the crosman valves have a sleeve inside the valve to decrease internal size? That in turn reduces FPS I think.
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Doesn't some of the crosman valves have a sleeve inside the valve to decrease internal size? That in turn reduces FPS I think.
yes they do, the 2300t and 2300S