Rob
In your current breech plug - when the flash hole becomes elongated, gas cut, or just plain worn out - one way to fix is to drill the plug out and install a vent liner with a new flash hole. Then you can replace the vent liner from then on and not have to replace the breech plug. With the wide use of BH and the hot shot primers that it takes to ignite it - you will see faster deterioration of the flash hole.
The Lehigh, vent liners are fairly inexpensive as compared to a new breech plug - especially when you start looking at the price of a 'speed breech'
This vent liner thing is another one of my 'Theories' or wild a--ed thoughts.... this come from the blue now and then.
No, I increased the hole size to increase the capacity of the BP to contain blow-bac. I must admit this was not totally my thought... It really originated with Grouse saying his new Knight Vision with a new Knight BP reduced 'blow-bac' dramitically - I wanted to knw why so he sent me the rifle. Then 'spitpatch' and I started talking about it, then I started thinking about the Triumph 'speed breech' and wondered why it was so clean? It all came down the 'spits' theory the size of the internal cavity would allow the more 'blow bac expasnion to be contained in the BP if the volume of the chamber were larger. The more volumn it contains the more time it allows the bullet to get out the barrel. When the bullet leaves the bore 'blow bac' is a non-issue -in fact it will even suck some 'blow-bac' with it.
And yes I think you could install different vent liners with different sized flash holes by a few thousands... Precision Bullets makes one, Savage makes one and even Randy Wakeman makes one, and even a guy on MM makes ones... the flash holes in each might be a different size.
I personally think the shape is a factor.... I believe the cone shape will deflect some of the 'blow-bac' pressure away from the flash hole and reduce the pressure going back through the flash hole.
Here are the differnet type of Omega breech plaus that I know of (picture from MLKieth)
The plug that I use is the second on the left. But you can see how they all guide the pressure in the bore right back to the center flash hole.
No I did not have to use the lathe... I used it this time because I wanted everything to be precise and exact fit. I have to more Knight FPJ plugs that have gon through the lathe also to be able to install the vent liners - we also increased the volume of the BP at the same time also in those and the Lehigh liners sceww in to them. I hope to test them this weekend with a new DISC Elite that I just got in the mail.
In the future I will do the same project on my bench drill press and machine vice. It really is prety simple + plus Lehigh Dave has indicated at one time that he might also provide the service when buying his vent liners... he would need to charge for that service...
I have not confirmed this with him....
The biggest fear.... sticking the vent liner in the BP especially when shooting T7. I will install it with a wee bit of anti-seze on the threads and a piece of teflon tape under the bell, But in realality it, really does not concern me with T7 - if you stick-it throw it in boiling water and expand the metal + T7 is water soluable... Yes, eventually the vent liner will wear out not necessarily the allen wrench insert - but the flash hole. But relacing them at $5 is really fairly cheap.
Don't be I love questions... the forum runs on questions...
Purpose of the vent liner... well basically I am
cheap! actually I am cheaper than 'Grouse' and he is always looking for good deals... I will not even shoot a steady diet of BH - cause I am cheap!
And I do think the vent liner provides benenfits...
BUT as Grouse has pointed out to me there may be a
DANGER that hear has some fear of... if for some reason that you remove your BP then remove the vent liner to clean it then
reinstall the BP with out
reinstalling the vent line (you forgot got busy whatever reason
) then loaded and attempted a shot - it certainly could be a bad issue -
SAFETY FIRST
Sorry this got so long winded - I am not a writer - never have never will be....
mike