Optima shim instructions?

[zach.trumble]

I've been reading about getting my optima v2 set up for BH 209.

I've read a few opinions about buying the Western Powders BP over the CVA BP.

What's this I read about shimming?

I've heard it mentioned but never explained.

Thank you for your time

 

[bestill]

Re: Optima shim instructions?

You simply press .005 shim or shims in primer pocket to achieve about.003 primer crush when closing action to get complete seal on primer.

Primer crush is say it measures .299 in length new and after cycled thru gun it measures .296 this would verify good primer headspace and seal.

 

[zach.trumble]

Re: Optima shim instructions?

Whew. Thanks for the response. I'm quite the newbie and will need more explanation. Maybe I can find a video.

The shim goes in the primer hole before the primer so it gets crushed a bit when you close the action?

I'm using CCI primers.

Thank you for your time

 

[chaded]

Re: Optima shim instructions?

The shimming you have probably heard about for the optima invovles shimming the firing pin bushing out from the frame with a shim kit from cva.

 

[zach.trumble]

Hum? Conflicting answers?

Shim the firing pin or the primer?

Thank you for your time

 

[Travis299]

Re: Optima shim instructions?

The reason for the shimming is to help with the blowback from the primer when firing as the primer blowback tends to foul up the firing pin assembly. The bushing that holds the end of the firing pin screws into the breech and by adjusting the bushing in & out with the shims controls how close the breech face is to the primer when the action is closed. This of course ASS-U-MES that ALL primers are the same which is not the case. I have found & use the O-Ring in the primer hole, instead of the shims, which performs the same function as the shims. The rubber O-Ring also works for the different length or size primers. The O-Ring is good for 20/40 shots and you can get 100 O-Rings for about $5. Here is the O-Ring site. https://www.mcmaster.com/#9262k611/=y73fh8

We use the O-Rings on our CVA Accura BP rifles and this has solved the blowback problem and it does not make any difference if you are using T7 or BH209 because the fouling is coming from the primer and not the powder charge. Using the O-Ring you will find that your fired primers are very clean when removed. You can push the O-Ring into the primer hole with a primer. Hope this helps and please ask if you need anything else of the subject.

 

[zach.trumble]

Great thanks. I assume that this is what the o-rings that come with the western powder BH 209 breech plug are for then? They go into the primer hole?

Thank you for your time

 

[ronlaughlin]

Re: Optima shim instructions?

First you purchase the kit, then by trial and error determine the number, and size of shims, after deciding on a primer.

In my rifle the shims produce about 0.0015" of crush to the W209 primer. My rifle probably could stand another 0.002" shim so for to get a tad more 'crush'. Too much shim will keep the hammer from cocking.

 

[Smyrnagc]

Re: Optima shim instructions?

We use the O-Rings on our CVA Accura BP rifles and this has solved the blowback problem and it does not make any difference if you are using T7 or BH209 because the fouling is coming from the primer and not the powder charge. Using the O-Ring you will find that your fired primers are very clean when removed. You can push the O-Ring into the primer hole with a primer. Hope this helps and please ask if you need anything else of the subject.

Hey Travis...Which primers are you using in your Accuras?

 

[zach.trumble]

Rinlaughlin - thanks for the pictures. That makes sense now. I noticed when screwing in my firing pin bushing that I can screw it past flush with the breech face. This bushing kit will solve that problem.

What is the problem exactly? What is wrong with not having it flush?

Thank you for your time

 

[ronlaughlin]

Re: Optima shim instructions?

A loose fitting primer may allow blow by. This can be stopped by using the rubber o-ring. Shimming the firing pin bushing, so there is a slight 'crush' of the primer, also stops blow by . The bushing on my Optima is proud of the breech a tad. Too much 'crush' won't allow the hammer to cock, or the action to close.

 

[Smyrnagc]

Re: Optima shim instructions?

A loose fitting primer may allow blow by. This can be stopped by using the rubber o-ring. Shimming the firing pin bushing, so there is a slight 'crush' of the primer, also stops blow by . The bushing on my Optima is proud of the breech a tad. Too much 'crush' won't allow the hammer to cock, or the action to close.

What primers are you using in your Optima Ron?

 

[ronlaughlin]

Re: Optima shim instructions?

W209

 

[sabinajiles]

Re: Optima shim instructions?

I've been reading about getting my optima v2 set up for BH 209.

I've read a few opinions about buying the Western Powders BP over the CVA BP.

What's this I read about shimming?

I've heard it mentioned but never explained.

Thank you for your time

I know it has sometimes been a point of contention on whether the Western Powders BH209 breech plug or the CVAs BH209 breech plug is best. As far as the actual breech plug goes, I have had several of both I can find no difference in them. I have measured every dimension on them and for all intents and purposes, they are identical. IMO, they are probably made by the same manufacturer.

The photos Ron posted are a great visual about shimming the firing pin bushing to get a proper primer fit to eliminate blow back. Anyone buying a CVA rifle should probably go ahead and get the firing pin bushing shim kit. If you contact CVA customer service and tell them your firing pin bushing does not sit flush with the breech face, they will send you one free of charge or they are only about $5 to buy.

A quick and easy solution to eliminate all blow back is to put a 1mm x 4.5 mm o-ring in the primer pocket. When you first do this, you might find the rifle breech doesn't shut tightly enough to allow cocking of the hammer. Usually, if you snap the rifle back closed firmly, it will take care of this and after doing it several times, it compresses the o ring and becomes easier and isn't an issue. An o-ring will last at least 20-30 shots and you can buy a package of 100 for less than $5. By the way, getting the proper primer fit to eliminate blow back is not just an issue with BH209. Blow back can, and will, occur with other subs. It just not as likely to negatively impact ignition.

 

[zach.trumble]

Re: Optima shim instructions?

Thanks for all the information this is very helpful. So both shimming the primer and the firing pin bushing accomplish the same task right? It's just about eliminating blowback from the primer. I think I have this problem because after only five shots or so my breech face is very dirty.

Thank you for the suggestion about contacting CVA, I will try that.

Thank you for your time

 

[GM54-120]

Re: Optima shim instructions?

Shimming the primer pocket causes less of the primer to sit in the primer pocket. Shimming the firing pin bushing does not.

 

[Travis299]

Re: Optima shim instructions?

A question was asked on what primers we were using on our CVA Accuras. Remington Kleanbore 209 Muzzloading Primers & we shoot the Barnes 290 gr T-EZ bullets.

 

[zach.trumble]

Here is the response I received from CVA:

"Thank you for taking the time to contact us.

The firing pin shim kit simply gets the firing pin bushing flush with the receiver. It is not designed to move the firing pin closer due to blowback. Blowback is normal and expected out of black powder guns.

Thank you,

Customer Service"

Guess I'm on my own to solve the problem.

Thank you for your time

 

[rangerod]

Re: Optima shim instructions?

I wouldn't even mess with the shim kit unless you know for certain if the bushing is not flush with the receiver. As CVA says the shims are not intended to be used to adjust head space. Flush up the bushing if necessary with the kit but use the o-ring to stop any blowby.

 

[zach.trumble]

Re: Optima shim instructions?

Thanks, I will try the o-rings first

Thank you for your time