Primer Blowby - Would this be safe?

[frontier gander]

I emailed CCI some days ago about their new inline MZL 209 primers and the tech told me the primer blowby that i am getting is most likely because of the loose fit inside of the breech plug.

Seeing how it was early and i was bored and wanted to fondle my Accura, i took it all apart and oiled up the trigger mech and then found some molly lube. I got wide eyed and an evil grin crossed my face and off i went to spray down the Accura's hammer/sear :lol: Smoooooooooth! Probably wasnt the great idea to use the dry molly because now the trigger is roughly around 1.5lbs and smooth as glass.

Alright, getting back on topic about the CCI's loose fit in the BP and the blowby, i went and use some 1/2" wide Teflon tape and cut a section 1 1/2" long and then cut it right down the center, enough wrap for 2 primers. I wrapped each primer up tightly and used Sabotloaders idea of going a little over the end so that when it goes off, the tape will blow back into the "threads" and seal off the blowby. Probably wont do a thing for me but hell, why not try it just to see?

Any danger in doing this? I was mainly worried about the pressure building up and having the primer fly back into the frame on my Accura. The Primers are really snug now and require my primer removal tool to get them back out.

I found some thinner sabots to use with the .451 ( i think) XTP's and ive upped my charge to 120gr Pyrodex RS and want to see how it does. Im not to worry about the group though, i want to get out of the house and do some shooting and just mess around with things to try out.

 

[TJJ]

Why not just find a better fitting primer? I am not an accura owner, but aren't they a tipper? I would think that if the action closes, you'd be fine. I've tried a few diferent primers, the ones that were ill fitting and left all that nasty-tuff fouling went in the give-away pile.

 

[gunrac]

I found the Win. W209 was the only primmer I didn't have blow-by with, in my Encore. Check the sticky above:

http://www.modernmuzzleloader.com/phpBB ... php?t=9798

 

[Underclocked]

I'm surprised FG is allowed to run loose. :wink:

 

[Okie Hog]

I found the Win. W209 was the only primmer I didn't have blow-by with, in my Encore.

My Encore is the same way. The worst offenders were the Winchester 777 primers.

 

[frontier gander]

Well heres the deal, Winchester 777s do the same thing, along with federal 209a's. Dirty as a SOB! They too fit loose but the main deal is, every primer ive tried, 777-fed 209A - Win W209 all leave HARD crud inside my barrel and makes reloading a second shot hard and a 3rd shot almost impossible. These CCI's load beautifully on a fouled bore, as much as 5 to 6 shots before it starts to get tight at the muzzle. They also hold a good group without swabbing. I was just tinkering around lastnight and wanted to see what the teflon tape would do and if it would help me in any way.

i'll be trying them out here in about 30 minutes after i get my first cup of coffee down.

 

[Busta]

It's a headspace issue. The manufacturers have to make the headspace long enough to accomodate the longest primers, the Winchester W209. In doing so, it leaves all the others with some slack.

The Win W209 is between .301" to .305" long, the CCI and Federal are between .295" and .299", and average .005" or so shorter than the W209.

I have at least 30, maybe 40 or more breechplugs, several custom made. I fit these breech plugs to the length of the primers for no blowback. I also have some that are self regulating with an o-ring in the bottom of the primer pocket.

If you want NO blowback, my experience is that you can go about it in two different ways. One way is you want about .002"-.003" interference when locking up a tip-up rifle. That means you will compress the rim of the 209 those couple thousandths when closing on the primer. This primer pocket will be .243" in diameter, the flame channel will be 5/32" in diameter, and the flash hole around .032". The second way is an unconventional way like the MU breeech plug is made. It has a primer pocket with an o-ring in the bottom, the only flame channel is the bottom of the primer pockets funneled shape that goes directly into the .040" diameter flash hole that has a short approximately .200" long channel to the powder pocket.

For the factory plugs to achive no blowback, you have to either be lucky, or seek out the best fitting primer for the application. Then manufacturing tolerances will also come into play, as most err on the side of too much space, than too little. It is easy to remove a thousandth or two from your breech plug, it is not so easy to add it back on. The manufacturers want to make sure the primer pockets are large enough so any primer fits, they don't care if it is loose, they just don't want to have to replace breech plugs that ar too tight to fit a primer.

It is my opinion that the flame channels are too small of a diameter in most of the factory plugs. CVA's are 3mm (.118"), T/C's are 1/8" (.125"), some of Knights are 1/8" (.125") and some are 5/32" (.15625"). My custom plugs have a .157" diameter flame channel, or basically none at all in the case of the MU plug. I also feel that you either need to get your flame into the charge instantly, or give it a large enough flame channel that it can accomodate the pressure without pushing blowback around the primer, or through the primer. A sort of pressure chamber large enough to contain the pressure of the primer, and blowback gasses.

My 2 cents.

 

[frontier gander]

wow amazing. i just measured 5 right out of the box and everyone of them were .297" right on the money. Winchester w209's are .301" on the 2 that i have left.

I'll look for an o ring in the shop after im done shooting and see what i can find.

 

[Batchief909]

Why not just get the proper fitting 209s?? That O ring will place the primer that much farther away from your charge. Might make it hard to close your breech too. 8)

 

[Busta]

wow amazing. i just measured 5 right out of the box and everyone of them were .297" right on the money. Winchester w209's are .301" on the 2 that i have left.

I'll look for an o ring in the shop after im done shooting and see what i can find.

I seriously doubt you will have room for an o-ring without modification of your primer pocket. I would order a new breech plug and see if it accomodates a shorter primer. There are no two made exactly alike, even though it may appear to be with the naked eye. It don't hurt to have an extra breech plug or thirty on hand. The breech plugs that I use the o-rings in are made with deep enough primer pockets to allow for about .010" to .015" of compressable headspace. Too much compression is not good, even though you may be able to get it to close. It will flatten the o-ring and reduce the ID, then there will not be enough room for your flame without blowing the ID of the o-ring down into your flame channel, thus blocking your flash hole. You don't want that happening, trust me!

 

[UtahRob]

Winchester primers in my Traditions pursuit pro ( i had ) were tight enough that i had to form fit them by closing my gun twice , but i had no blow by until the breech plug got fowled with carbon and then it would bulge the primers on the sides and then blow by . If they made a very weak but long 209 primer it would work as good as my 25 acp conversion with 777 . Too bad BH209 needs such a hot primer ,