Need some help

Need some help

Joined: November 10th, 2004, 2:57 pm

August 26th, 2011, 4:02 pm #1

I modified an old 2240, with the following
1. 2250B air tube, cut, and drilled for QB79 tank block
2. 2260 barrel
3. Muzzelmack Extended bulk Fill Adapter
4. Valve body with the Bio mods, and opened ports in the barrel, has stock valve spring and the valve stem from an AS2250 valve.
5. Martin Paredes Multiable Calibre Repeating Breech, with the Marauder clip
6. Stock hammer and spring.
Now when a pellet is fired the gun goes BRRRIP like the hammer is vibrating back and forth. I guess there is a spring that needs to be changed, but what one? Steve's HDD is not an option due to the breech I'm using.
TIA
fritzalee

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Joined: June 29th, 2009, 6:38 pm

August 26th, 2011, 6:51 pm #2

Sounds like you need either a stronger valve spring or a weaker hammer spring. Where is your velocity? Is it where you want it or ?

Tom



"What, me worry?"

"If I were two faced would I be wearing this one?" - Abe Lincoln
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Joined: November 10th, 2004, 2:57 pm

August 26th, 2011, 7:57 pm #3

Tom, I haven't checked velocity, will do that after changing hammer spring, I also need to modify the hammer, the bolt needs to be pulled back hard to set the trigger sear, if I forget, then there are two pellets seated in the barrel. I hope I can get it up to where the long barreled 2240 was shooting in the low 700's with 12gr carts, had a Tim Miller modified valve in it then.
fritzalee
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Joined: September 26th, 2003, 2:20 am

August 26th, 2011, 8:45 pm #4

Sounds like you need either a stronger valve spring or a weaker hammer spring. Where is your velocity? Is it where you want it or ?

Tom



"What, me worry?"

"If I were two faced would I be wearing this one?" - Abe Lincoln
The hammer is bouncing because your transfer port is leaking.

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Joined: June 29th, 2009, 6:38 pm

August 26th, 2011, 11:03 pm #5

Never heard that cause before. Good to know. Why would that port leak cause that?

Tom



"What, me worry?"

"If I were two faced would I be wearing this one?" - Abe Lincoln
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Joined: September 26th, 2003, 2:20 am

August 27th, 2011, 12:39 am #6

If the port is leaking, the gas escapes into the tube in front of the hammer and pushes it back. The hammer then strikes the valve again, releasing a bit of gas. The cycle is repeated, each time releasing less gas than before until there isn't enough gas pressure to move the hammer far enough to strike again.

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Joined: November 10th, 2004, 2:57 pm

August 28th, 2011, 12:35 pm #7

Dave,
Thank You for this info, when I modified the valve I used a fine file to flaten the transfer port seat, bet that is where the problem is. The MCRB came with a clear softer tube, and I may have cut that too short.
fritzalee
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