O-Rings for Shimming Primer Pockets?

[Travis299]

I am sorry that the pic of the fired primer appears that an O-Ring is on the primer base BUT that is nothing but the metal primer. The rubber O-Ring is inserted into the base of the primer pocket and it stays there until removed with a spring hook or similar tool. I assure you that the pic is only the metal primer case after being fired in my CVA.

 

[MSalyards]

Yup, compresses between the end of the primer and the inside of the BP.

 

[Chris W.]

I use the buna-n in both my Optima rifle and pistol. Works great in both preventing blow back.

 

[snapbang]

OK. I got it. Really glad you took the time to get me straight on that. I always thought it went in the primer hole (at the bottom). I was using shims but I ran out and never replaced them. A couple times the action was hard to close. Probably a long primer.

Im thinking I will like these better. Thanks again.

 

[OXN]

It does look like there is an oring on that primer. I think its just the lighting maybe. But no, the oring goes into the primer hole, then the primer goes into the primer hole. Oring usually will stay down there in the hole.

Necromancing this to see if you guys can take me to school here for a sec. Correct me if I'm wrong anywhere in the following.

There are two applications for O rings in the shimming of 209 ignition systems (of break action muzzleloaders such as CVAs). One is as described above- O ring goes into primer pocket before primer, then everything loads and fires normally. This basically seals the base of the primer to the breech plug to prevent blowback. These are the O rings linked above.

O rings can also be used between the firing pin bushing and the receiver, to cause the firing pin bushing to sit either flush or a few thousandths out, in order to "crush" the primer into the primer pocket and create a seal directly between the metal of the primer and the breech plug.

Missing anything?

 

[OXN]

Also, if anyone has a few extra of the above linked O rings laying around they'd want a few bucks for, shoot me a PM!

 

[michiganmuzzy]

One is as described above- O ring goes into primer pocket before primer, then everything loads and fires normally. This basically seals the base of the primer to the breech plug to prevent blowback. These are the O rings linked above.

Correct

O rings can also be used between the firing pin bushing and the receiver, to cause the firing pin bushing to sit either flush or a few thousandths out, in order to "crush" the primer into the primer pocket and create a seal directly between the metal of the primer and the breech plug.

This wouldnt get an oring. It would get an actual shim. I have shimmed mine out and its good. But the oring in the primer pocket, imho, works better. I can use any 209 and get a good seal. Shimming the bushing gives a good seal, for me, only with a specific length primer. But it did have the additional benefit of moving the slot in the bushing to vertical so i have less problems with swollen primers, from heavy loads, catching in that slot.

 

[OXN]

Correct

This wouldnt get an oring. It would get an actual shim. I have shimmed mine out and its good. But the oring in the primer pocket, imho, works better. I can use any 209 and get a good seal. Shimming the bushing gives a good seal, for me, only with a specific length primer. But it did have the additional benefit of moving the slot in the bushing to vertical so i have less problems with swollen primers, from heavy loads, catching in that slot.

All makes sense. My Wolf came with a very thin O ring around that lip on the firing pin bushing, which wore out and fell off during cleaning. I do seem to remember there being less blowback before this happened. Do suppose I may try to track down one of those shim kits.

 

[michiganmuzzy]

I have that info around somewhere. I'll find it.

 

[Footindave]

I just grabbed a couple bags as well if you need me to send you some to try I will gladly do so

 

[JMEUSMC]

Also, if anyone has a few extra of the above linked O rings laying around they'd want a few bucks for, shoot me a PM!

 

[JMEUSMC]

Uxcell Nitrile Rubber O-rings 6.5mm OD X 4.5mm X 1mm thick that work great for about 20-30 shots are available on Amazon. For break action guns, make sure you close the action sharply to ensure that it locks securely. Otherwise, you won't be able to cock the hammer.

 

[michiganmuzzy]

The shims for the firing pin bushing are
9.951mm X 7.688mm X .005
460B4008 at McMaster-Carr
(Thanks to GM54-120 for finding them)

 

[OXN]

The shims for the firing pin bushing are
9.951mm X 7.688mm X .005
460B4008 at McMaster-Carr
(Thanks to GM54-120 for finding them)

You guys are gentlemen and scholars. That's specific to CVA firing pin bushings, correct? I didn't break out the calipers to measure, but I'll say 90% sure those bushings are are the same in all CVA break action models...

 

[michiganmuzzy]

Yes, they do fit the CVA bushings. They come in a 5pak. I used 2 on my Accura bushing. They should also fit the Optima and Wolf V2's I still have the oring on my bushing too. Probably the all the V1's as well

 

[Travis299]

FWIW, pic of fired & unfired primer. The fired primer was using the O-Ring in the primer pocket base. Note - no O-Ring on the primer.