User Report QB transfer port seal

User Report QB transfer port seal

Joined: June 7th, 2010, 12:14 am

September 7th, 2010, 1:55 am #1

During a recent "strip and reassemble" of my AR2078A, a 007 Buna-n o-ring was used to replace the poly tubing. the o-ring drops right in! Looks like it's made for the purpose.

After a round of shooting today (appx 70 shots)

All is good!

It looks weak on the left side due to slightly off center registration of the striker tube and the bolt/ barrel tube, but the o-ring is holding so far.


CalG
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Joined: July 2nd, 2006, 6:50 pm

September 7th, 2010, 2:32 am #2

I am tired of Manufacturing TP seals, not to mention milling flats on the valve and breech.

David

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Joined: July 2nd, 2006, 6:50 pm

September 7th, 2010, 2:54 am #3

During a recent "strip and reassemble" of my AR2078A, a 007 Buna-n o-ring was used to replace the poly tubing. the o-ring drops right in! Looks like it's made for the purpose.

After a round of shooting today (appx 70 shots)

All is good!

It looks weak on the left side due to slightly off center registration of the striker tube and the bolt/ barrel tube, but the o-ring is holding so far.


CalG
I found my bolt was bent a while back. I beat it to about 15 thou, then had to take a torch to it and got it to just 2 thou out. I'll let you know the outcome when I get the gun back together. I ordered some JM buttons for the cocking block. Just to much slop in it for me.

David

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Joined: June 7th, 2010, 12:14 am

September 7th, 2010, 3:10 am #4

The cocking effort is much improved. In both directions. open and close.

The bent bolt was straightened using the Hyd, press. Easy, but fussy. V-blocks and dial indicators etc. The bore of the bolt housing was lapped with a brass lap charged with Clover compound, as was the striker bore. The pressure release key hole was a major hang up.

Much improved, but there was a hitch in the giddyup! It was the tigger! Cycling the action while cocked showed the weakness!

The trigger sear (not the striker sear) as it slides over it's mating surface on the "chicken head" as I call it, during the cocking motion, had a major hitch. The defect in metal was easily discerned with a hand glass. A few moments with an oil stone....viola! much better. Smooth!

I also soft soldered a dime onto the bolt handle to give my thumb a bit of pad and purchase. With the "trigger finger" curled around the trigger guard, closing the bolt with my thumb is now comfortable. (not effortless


These QBs are a riot!
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Joined: May 12th, 2001, 1:29 pm

September 7th, 2010, 3:49 am #5

During a recent "strip and reassemble" of my AR2078A, a 007 Buna-n o-ring was used to replace the poly tubing. the o-ring drops right in! Looks like it's made for the purpose.

After a round of shooting today (appx 70 shots)

All is good!

It looks weak on the left side due to slightly off center registration of the striker tube and the bolt/ barrel tube, but the o-ring is holding so far.


CalG
http://www.network54.com/Forum/113813/m ... port+seal-

Steve
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Joined: July 2nd, 2006, 6:50 pm

September 7th, 2010, 10:22 am #6



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Joined: April 18th, 2009, 7:23 am

September 7th, 2010, 11:29 pm #7

During a recent "strip and reassemble" of my AR2078A, a 007 Buna-n o-ring was used to replace the poly tubing. the o-ring drops right in! Looks like it's made for the purpose.

After a round of shooting today (appx 70 shots)

All is good!

It looks weak on the left side due to slightly off center registration of the striker tube and the bolt/ barrel tube, but the o-ring is holding so far.


CalG
90 duro or 70 duro?
Does it make a difference?
This is what I found.
http://shop.ebay.com/i.html?_nkw=buna+r ... m270.l1313

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Joined: June 7th, 2010, 12:14 am

September 8th, 2010, 12:19 am #8

I would select the hardest toughest stiffest deadest rubber compound I could find.

Ahh the 90 shore.....

Kind of like a pre-moulded bit of poly tubing
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Joined: March 3rd, 2005, 1:38 pm

September 8th, 2010, 10:46 am #9

The cocking effort is much improved. In both directions. open and close.

The bent bolt was straightened using the Hyd, press. Easy, but fussy. V-blocks and dial indicators etc. The bore of the bolt housing was lapped with a brass lap charged with Clover compound, as was the striker bore. The pressure release key hole was a major hang up.

Much improved, but there was a hitch in the giddyup! It was the tigger! Cycling the action while cocked showed the weakness!

The trigger sear (not the striker sear) as it slides over it's mating surface on the "chicken head" as I call it, during the cocking motion, had a major hitch. The defect in metal was easily discerned with a hand glass. A few moments with an oil stone....viola! much better. Smooth!

I also soft soldered a dime onto the bolt handle to give my thumb a bit of pad and purchase. With the "trigger finger" curled around the trigger guard, closing the bolt with my thumb is now comfortable. (not effortless


These QBs are a riot!
remove the bolt and heat the round head with a torch, then flatten to about 1/4 inch thick and shape, I went with a half moon shape on my match AR2078A, you then only need your thumb to close and with the polishing up of the internals it works great...

mailto:flyingdragonairrifles@hotmail.com
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