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Head Spacing Conundrum..........

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Head Spacing Conundrum..........

Old 04-17-2012, 05:25 AM
  #1  
Fork Horn
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Question Head Spacing Conundrum..........

I'm pointing this primarily at MountainDevil54, but anyone can chime in if they would like.
-First off, I've got a new (bought at xmas 2011) CVA Optima 50 with the standard breechplug(not the BH209 plug).
I shot it for the first time on Sat with good results but alot of blowby.
-Last week I contacted CVA and they sent me a shim kit. Yes I know their not avail to the public yet, but they sent me one.
-In the package there were 4 shims measuring(measured with a goverment calibrated Starrett Electronic Digital Caliper): 1x .0025, 1x .005 and 2x .010.
-I've read all the posts here and on your website/blog concerning the headspacing required for a crush fit and was confident I got get it done with no issues.
-Sorry no pictures, but from the factory, the firing pin bushing was slightly below the breechface. Telling me that there would be alot of shimming needed to achieve near the .016 recommended.
-Performing the removal of the bushing, installing a shim and measuring NUMEROUS times never achieved near the recommended .016".
-Now with all the shims inplace and the o-ring and the bushing tightened snuggly, the bushing face protruded approximately .012 from the breechface. And with a CCI209M primer installed there was no noticable gap and no resistance to closing the mechanism.
-The bushing was adjusted to .016". I can feel the o-ring still contacting the seating surface, but it can be described as a loose fit.
-Install another primer and check for the plug to breechface gap, with no difference.
-So I get a new primer and measure with calipers the primer, .297".
-With the bushing set at .016, measured primer installed, I close the action firmly (no gap noticed again) and remove and remeasure the primer. .297"
-So now I start working the bushing outwards, increasing the head spacing. 1/8 of a turn at a time, the bushing is now somewhat loose(easy to turn to the point that I can do it with the pad of my index finger inserted into the action). I have a primer installed and am adjusting and closing the action looking for that gap...
-it doesnt occur until I have the bushing out approximately .030 and now I know the bushing face is making contact with the primer cause I can feel it, but the action now will not close easily. It needs a firm snap to engage the latch.
-So, I turned the bushing inwards approx 1/8 of a turn and the action closed. Opened the action again and firmly closed. Measured the primer, .295" Only a .002 crush.
-So now with approximately .030" of headspacing I can finally achieve something, but from everything I've read, it's not nearly enough and the bushing is easy enough to turn with finger pressure. I know a bit of teflon tape will tighten it up.
-With everything I've read concerning head spacing, the adjustments Ive done so far are extreme! Is this bushing out too far?
-Do I continue until I achieve the recommended .012 to .016 crush?

Thanks
Alex
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Old 04-17-2012, 05:57 AM
  #2  
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This does not sound to good something is out of specs or would be if it was a TC.
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Old 04-17-2012, 06:13 AM
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0.012" crush is too much. Try to achieve about .005" crush. One needs to 'snap' the action shut to achieve 0.005" crush. It appears you need another shim kit.
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Old 04-17-2012, 06:25 AM
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Ron,

Thanks and understood. But from everything I've read from MD54's postings, the action should be able to be closed without "snapping" it shut. But Ive read elsewhere that it really needs to be "firmly/snapped" to get the action closed. I didnt want to ruin anything by doing it TOO much....
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Old 04-18-2012, 05:17 PM
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Firm snap will do. You see guys on tv just slamming them shut and it just makes me shake my head.

My Accura V2 and Wolf both took .032" worth of shims in order to move the bushing out .016" Primer seal is between .0045? - .005" crush fit.
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Old 04-18-2012, 07:08 PM
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http://gandersmuzzleloadingblog.blog...ent-shims.html
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Old 04-19-2012, 06:40 AM
  #7  
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So, CVA is sending me a complete shim kit this time, plus I've got a BH209 BreechPlug & powder tubes enroute from WesternPowder. It is stated also to have a shim kit with it. I'll be stopping at BassPro on the way home from turkey hunting on Saturday and get a container of BH209 and a powder measure. I'm not going to try to headspace anything again until I get the new breechplug... I'll keep you all informed on the process.
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Old 04-20-2012, 08:25 AM
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On my optima pro pistol I ended up using a .020 o ring (dont quote me) and still used a little bit of teflon tape. Works like a charm. Everything is nice and flush with no blow back.
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