Ultra-lite question

dotman

WKR
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Feb 24, 2012
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8,201
Purpose is to waterproof it, it is a good seal but plastic is less resistant to high pressures then metal. So yes blowback may increase but have to fire it to get that other wise the seal is good.
 
Joined
Nov 30, 2012
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Northern Idaho
And the purpose of the plastic jacket is ????

If blowback is increased, wouldn't that indicate a worse seal?

The FPJ provides a completely water tight breech. you could stand the breech in water for days take it pull the trigger - boom

But, if you get the compression right on a NFPJ you could do the same thing also.

The blow back comes from the stretching of the FPJ around the nipple when the blow back pushes back.
 
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pete

Lil-Rokslider
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Jan 29, 2014
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145
FPJ - Full Plastic Jacket and in your case it is a red plastic jacket. This is the red jacket primed with a 209 shot gun primer.

m901110_600-248x250.jpg




If the breech plug looks like this it is a FPJ system

M900018-600-250x250.jpg


If it looks like this.... it is a NFPJ system - Non Full Plastic Jacket

M900020-600-250x250.jpg


You also will need the correct bolt to go with the BP that is installed in your rifle

Hope this helps a bit..

Thanks for the help, I ended up getting the same info from a knight customer rep, and confirmed that it has the rpj system. I got the rifle, but I need to review some of the other threads on here to decide on my sight setup. Sabotloader - I'm going to thank you now for all of the info that you've provided on this forum, I know I'm going to use it.
I'll update this thread when I get it all setup.
 
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pete

Lil-Rokslider
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Jan 29, 2014
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145
Truthfully when I got my ultralight I picked up the bare primer kit, I really like the FPJ system and haven't even tried the bare setup. Save your red jackets and wash them, they can be reused a few times before the primer pockets loosen up.

I get the blow by theory, I've only used BH209 and blow by just doesn't seem to be an issue for me.

This is good to know, I had thought about getting the bare primer kit, but I'm going to definitely pass on it now.
 

jm1607

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Jul 26, 2013
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Location
Houston, TX
The FPJ provides a completely water tight breech. you could stand the breech in water for days take it pull the trigger - boom

But, if you get the compression right on a NFPJ you could do the same thing also.

The blow back comes from the stretching of the FPJ around the nipple when the blow back pushes back.

So you think the NFPJ is just about as waterproof as the FPJ with a well seated primer?

I guess neither are too waterproof without a primer... Could I just run an FPJ without a primer till I'm ready to out one in?
 
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