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PostPosted: Fri Oct 23, 2015 8:33 pm 
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Joined: Sun Apr 13, 2014 9:14 pm
Posts: 661
Location: Mississauga, ON
Good stuff, Raven. It IS interesting. Good to see that the two chronys are so close in readings. I wonder why the YouTube link I posted shows such a major difference between the two? Looking forward to the results of your hammer spring mod. I didn't try anything in that area. I was able to find out that the only difference between the Canadian and the US versions of the CX4 was the "valve bushing" so that was the area I focused on, and indeed it proved to be. Like others my main interest was in getting the output closer to 500 fps allowed here - I now have to reduce the hole size in the valve bushing to back things off a little.

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Daisy 953 * QB78D * Walther 1894 * Beretta CX4 & PX4 * Zoraki HP01 * Beeman P17 * Walther CP88 Comp. * Crosman 1377/2240/SA6/357-8
Swiss Arms P92 * Colt Commander 1911 * Walther PPK * P08 * Colt Python 357 * TW 1911/Limited * S&W M&P R8


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PostPosted: Sat Oct 24, 2015 3:24 am 
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Joined: Sun Oct 18, 2015 5:51 am
Posts: 26
Location: Northumberland uk
Ok using the photos which may I add are a godsend off lleader I stripped down gun removed old hammer spring and replaced with one Armex the uk dealership for umarex kindly sent me free of charge very pleased with results rws super domes are now running at 420fps , dynomit nobels up to 528fps , I noticed the old hammer spring was shorter than the new replacement new 62mm long old 55mm long , sadly I forgot to count number of coils , but on reflection it might be caused by not decocking gun correctly at the end of a session thus leaving hammer spring compressed but this is purely guessing, overall I am happy with the outcome as now at 6 joules approx 4.5ft/lb which is more than enough for my target shooting needs , 8)

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Qb78dl, xs78, xs79hpa
Berreta cx4 storm
Hw80k, Hw77
Logun solo
S200
Bam51, B2, B45-3
Xs19, xs20,xs36-1,xs36-2,xs38
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PostPosted: Sat Oct 24, 2015 8:34 am 
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Joined: Sun Oct 18, 2015 5:51 am
Posts: 26
Location: Northumberland uk
Ran a series of pellets
Dynamit nobels 7.2grs
541,548,552,549,560,568,567,586,576
SD 45fps av 561 ,5ft/lb 6.6joules
Rws hollow points 6.9grs
567,572,568,571,568
SD 5fps av 569, 5ft/lb 6.6 joules
Rws superdomes 8.3grs
533,524,531,538,545
Sd 21fps, av 534 ,5.3ft/lb, 7 joules
As figures show the hollow points have the best spead only 5fps
Superdomes however gain highest output
Will monitor guns performance as time goes and spring beds in but very happy with these results

_________________
Qb78dl, xs78, xs79hpa
Berreta cx4 storm
Hw80k, Hw77
Logun solo
S200
Bam51, B2, B45-3
Xs19, xs20,xs36-1,xs36-2,xs38
Webley mk3, osprey
Lion
Crosman 1740,2250
Paratrooper .22
P17,Orginal10,webley senior,junior Cp1,powerline 717


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PostPosted: Sat Oct 24, 2015 12:54 pm 
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Joined: Sun Apr 13, 2014 9:14 pm
Posts: 661
Location: Mississauga, ON
Wow! Good stuff - better than I expected. Virtually the same as I got with the larger holed valve bushing. Which begs the question, what if one did both mods?. :twisted: Nah - I'm not going to go there. Already got more than I need.

Another thing to keep an eye on - I have occasional miss-feeds of pellets, ie: not indexing into place. No difference across three different magazines. I have a couple of theories about this. One is that since the same valve full of air is used to propel the pellet out of the gun (by exiting the front of the valve) and to blow back the hammer (by exiting the back of the valve, inside the hammer) if you increase the amount going to the pellet there is less left for the blowback. The hammer being blown back is of course what indexes the next pellet into position by striking the pivoting lever above the hammer.

Another possibility is that I still have to clean out more of that moly I was liberally applying. :?

A third possibility is that I bent something when I had the gun running in full-auto. The hammer ran full auto but the poor pellet indexing system didn't stand a chance of keeping up. I have completely taken everything apart and inspected it and there does not appear to be anything bent or otherwise damaged.

IF (and it's a big IF) the first theory is the problem then you might have more of a problem than I do. I just have more of the air charge going to the pellet. You have more air going to the pellet and a heavier hammer spring for the blowback air to fight against. Anyway, this is all speculation on my part - let me know how your gun performs.

_________________
Daisy 953 * QB78D * Walther 1894 * Beretta CX4 & PX4 * Zoraki HP01 * Beeman P17 * Walther CP88 Comp. * Crosman 1377/2240/SA6/357-8
Swiss Arms P92 * Colt Commander 1911 * Walther PPK * P08 * Colt Python 357 * TW 1911/Limited * S&W M&P R8


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PostPosted: Sat Oct 24, 2015 2:13 pm 
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Joined: Sun Oct 18, 2015 5:51 am
Posts: 26
Location: Northumberland uk
Forgot to mention the valve bushing is the same as the USA version plastic ,as for the blowback indexing it only failures I've encountered was when co2 was getting low,sometimes it would take a sec pull of trigger to fire correctly suggesting the co2 was too low after firing to advance mag ,by waiting it allowed pressure to stablise enough to allow blowback to operate the magazine correctly

_________________
Qb78dl, xs78, xs79hpa
Berreta cx4 storm
Hw80k, Hw77
Logun solo
S200
Bam51, B2, B45-3
Xs19, xs20,xs36-1,xs36-2,xs38
Webley mk3, osprey
Lion
Crosman 1740,2250
Paratrooper .22
P17,Orginal10,webley senior,junior Cp1,powerline 717


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PostPosted: Sat Oct 24, 2015 2:32 pm 
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Joined: Sun Apr 13, 2014 9:14 pm
Posts: 661
Location: Mississauga, ON
Raven2007 wrote:
Forgot to mention the valve bushing is the same as the USA version plastic

Hmmm. Since you were only getting upper mid 300 fps with the larger holed valve bushing and that's what I was getting with the smaller valve bushing it seems to me that I already have the stronger hammer spring. ie: the British guns were cut back in power (for whatever reason) with a weaker hammer spring and the North American guns were cut back (for the CDN market) with a smaller valve port.

I believe I recall reading in the past, unless I'm confusing the CX4 with another gun, that some British CX4's came with a smooth barrel instead of rifled. Are you aware of that, or am I having a senior's moment here.

_________________
Daisy 953 * QB78D * Walther 1894 * Beretta CX4 & PX4 * Zoraki HP01 * Beeman P17 * Walther CP88 Comp. * Crosman 1377/2240/SA6/357-8
Swiss Arms P92 * Colt Commander 1911 * Walther PPK * P08 * Colt Python 357 * TW 1911/Limited * S&W M&P R8


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PostPosted: Sat Oct 24, 2015 3:01 pm 
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Joined: Sun Oct 18, 2015 5:51 am
Posts: 26
Location: Northumberland uk
Yes your correct ,early version were rifled but later versions were smooth bored ,luckily when mine was apart checked its rifled so either a early uk. import or a German import :)

_________________
Qb78dl, xs78, xs79hpa
Berreta cx4 storm
Hw80k, Hw77
Logun solo
S200
Bam51, B2, B45-3
Xs19, xs20,xs36-1,xs36-2,xs38
Webley mk3, osprey
Lion
Crosman 1740,2250
Paratrooper .22
P17,Orginal10,webley senior,junior Cp1,powerline 717


Top
 Profile  
 
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