I was just comparing a new breech plug for my Mustang to a new one for my Omega X7. The flash hole on the Mustang plug is a larger diameter than the X7.

So I'm wondering - has anyone conducted an experiment by progressively enlarging the flash hole on a breech plug to see what effect it had on accuracy and on the amount of fouling in the breech area?

"IF" the fouling in the breech area is primarily from the primer, would a larger hole allow more of the primer flash to enter the barrel rather than blow back into the breech area? If so, I wonder how large you could safely go.

Semi

Thinking out loud... Increasing the size of the flash hole would/will definitely allow more of the 'blast' from the HOT 209 primer to exit the flash channel through the 'opened' flash hole. The other benefit of this is that it will allow the more heat and more flash from the primer to enter the bore, which in-turn will allow ignition of the BH load. This will also or should reduce the amount of carbon build up in the 'flash channel' of the breech plug. Shooting primer after primer should not cause a problem or a build up in the BP.

But! I fear that opening the flash hole to much might end up causing another problem - with the increase of real blow back pressure against the primer and the what ever method your particular gun may have to hold the primer in place. This pressure should/will increase as the powder volume rises and or the weight of the bullet gets heavier and the pressure remains on the bottom of the primer longer.

Another adverse result of this pressure build up on the bottom of the primer - it may cause a bulge in the primer making it difficult to get the primer out of the BP. This can be reduced some buy using a copper clad battery cup instead of the aluminum cup that a lot of primers are now using. I use a Cheddite primer for shooting BH because of that reason, it has a copper cup, it acts more like a shell in a chamber in that it expands and contracts more than the aluminum cup.

It SEEMS to me the an opening of 33/35 was the suggested flash hole diameter for BH. And it SEEMS to me that the greater the opening the greater chance of real pressure blow back.

All of this is just THINKING no hard facts....

I can not remember if Utah actually shot regular BH loads and what weight projectile he might have been using....

For myself - when shooting BH it is pretty easy to twist drill the flash channel out after about 12 shots... and I have not had a problem with the flash hole plugging 'YET' now watch it happen but I shoot far more T7 than I do BH....

Drilling out a flash hole is not the way to go. Tried that with a CVA gun when i had trouble igniting the old Clean Shot pellets. Never did get the pellets to light reliably. It did greatly increase the amount of blow by and it made the primer much harder to remove.

Actually if you think about it that's an unnecessary experiment as the reason we have to change breach plugs after a certain amount of shooting is because when the touch hole is flame cut bigger beyond a certain point accuracy starts going down hill or blow back increases.

I'm glad you brought that up Lee. I've seen reports of breech plug flash hole erosion on several forums and wonder what's the norm - because I haven't experienced it yet.

I bought my Mustang new in Feb. `07. It was my first in-line, and my only one until I fell for the X7 last December. Now I have at least a thousand shots out of the Mustang's original breech plug, which I converted to .25 ACP somewhere around shot number 300. I recently bought a new plug so I can switch back to 209s with Blackhorn. The flash hole in the original plug is exactly the same size as the new plug's hole, so it evidently has not eroded at all.

I have had to replace 3, two in the Omega and one in the Triumph. The first one in the Omega did not last long 200to 250 shots I think it missed heat treat. The others lasted through a case of powder or a bit more. Lee

Having a smaller hole acts like a venture it will push the flame faster and further threw the charge allowing a almost full instant charge burn

Semi

I also have been pretty fortunate when it comes to BP's - I have not replaced one yet that I remember - I still have the original for the Omega which I converted to 25acp several years ago. i do have extra BP's and nipples for everything but it has been more a precaution than a necessity.

I think part of it may be that i do not shoot a lot of what I call really hot loads or primers since I have not fallen to lure of BH I still use relatively cool primers.

And another answer maybe that I have not shot the Knights or the Triumph enough to see the problem yet...

And really that may a good reason for the Cayugad 'theory of acquisition' - the more you have and shoot the more difficult it will be to wear anything out on anyone of them

Now you see Sabotloader, you can learn something new every day on this forum. I've never heard Cayugad's Theory of Acquisition stated so clearly before. I guess I'd better get with the program.

Some times a picture helps, this is the BP that got to the point of opening up my groups and the one I am using now that has only a couple cans of BH through it.