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PostPosted: Sun Jun 08, 2014 1:51 am 
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Joined: Fri Jun 26, 2009 7:42 am
Posts: 4080
Location: Somewhere In Time
AirGunEric wrote:
Joel has obviously had some success with them as he indicates, but also note that he mentions weight and spring pre-load, not just weight.

Yes without that extra preload on the spring the weight just slows it down with no positive outcome in my experience. I have seen anywhere from 20-50FPS increase in .22cal using these slightly longer/heavier tophats, nothing mind-blowing, just a little bump in FPS...

I will be designing a delrin tophat with a steel insert, that way I can make it a snug fit to the ID of the spring to help quiet the shot cycle, as well as adding preload/weight...Should be a fun experiment in any case

"Are you guys silly? I'm still gonna send it..."

PostPosted: Sun Jun 08, 2014 8:41 am 
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Joined: Wed Jul 01, 2009 3:23 pm
Posts: 3067
Location: Northern Ontario
Current Phantoms come with a bleed hole in the piston. Plug it and you are done.

"The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants." - Thomas Jefferson.

PostPosted: Sun Jun 08, 2014 10:03 am 

Joined: Thu Dec 15, 2011 11:24 am
Posts: 331
Thanks for the replies jgoodz, Eric and Chevota.

I knew there was a point of diminishing return by adding weight, but had not realized just how much brass shim stock weighed. And to be honest had forgotten about the spring preloading compression gained with respect to tophats.

Knowing that a lot of guys use pop bottles to make their sleeves, I measured one and it was 0.01" thick. Rolled brass has a weight of 8.56 g/cm3. So assuming a 3/4'' piston diameter, cutting out a slot and adding tabs at the end...the sleeve should come in at about 14-15 grams...or about the equivalent weight of a 1/4" thick .75" diameter disk of steel (rolled steel weight of 7.93 g/cm3) that's surprisingly heavy.

I'd like to apologize to the original poster for taking his thread a bit off topic.

PostPosted: Sun Jun 08, 2014 8:07 pm 
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Joined: Thu Sep 01, 2005 1:41 pm
Posts: 997
Location: GTA
Chevota wrote:

That decocking thing is super annoying imo and I remove/trash them first thing. It's actually called an anti-bear trap device meant to minimize the chance of the barrel snapping closed while open to load it and "bear trapping" your fingers. There's little risk imo of getting your fingers pinched, but it is possible. A side effect of the device is you can't decock the gun. A bonus of the device is you're less likely to bend the barrel. You see if you pull the trigger while the barrel is down, without that device, the barrel snaps closed with enough force that it bends upwards as the block stops and the barrel keeps going. Very common problem with break barrel guns, especially in the hands of curious people. Since it is a safety feature I can't suggest you remove it, but I do.

Getting your finger caught in the breech area is not your only concern. I had an old BSA Meteor as a kid that didn't have a trigger guard. With the barrel in the down position I some how pulled the trigger, the resulting whack in the head was something I would never want to happen again. The barrel flew up so fast andhot so hard I didn't really know what hit me. To be honnest I am surprised I didn't crack my skull, or did I? That would explain a few things..

For the price of a new sping, or a lost shot hunting I think I will keep my anti bear trap mechanism in place.

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