BuckDoeHunter,
Never heard of such a thing, what is an o-ring?
Seriously, I have been doing this for a couple years in a few of my custom and customized factory breech plugs. This was due to the fact that I don't like blowback and am always looking for a "better mousetrap". With the introduction of Blackhorn 209 powder, I wanted to be able to use this powder in my favorite rifle, a NEF Huntsman. I have tested this powder in my Knights, Whites, H&R, NEF, and others T/C's and CVA's. What I found out right away, was that this was not going to work reliably in my standard factory NEF breech plug, or the PR .25 ACP conversion breech plug, even with Small Rifle Magnum Primers. So I had to either find a plug that would shoot it reliably, or find one that I could modify to work 100%.
25 acp breech plug.
The first custom plug I tested was the Hubbard plug. It worked well, but I was still left with blowback. This plug headspaces off the rim of the 209 primer, and soot bleeds back out around the primer. Iknew I could come up with something that would at least reduce this. Then it hit me, an o-ring in the bottom of the primer pocket would seal the face of the primer. I was very surprized at the results, no blowback. This plug is a two-piece, and really not what I was looking for, as I still had to use the crappy standard NEF breech plug wrench (which I also modified several years ago).
Standard NEF breech plug on left, Hubbard on the right.
Just a small picture of some other successful mods I have done along the way. Trust me, you don't want to see them all, nor do I have the time to compile it.
L to R; Standard NEF plug without primer carrier (POS), my custom #11 primer conversion, standard 209 plug with primer carrier, .25 ACP breech plug, custom Hubbard breech plug.
This is a uni-bushing .25 acp back to 209 primer conversion.
This is a upside down .25 acp back to 209 conversion. This required turning down the rim slightly, and taking a little off the mouth. This worked very well, but did not conquer the blowback problem, and I had to use the brass.
Then my prayers were answered. Nick contacted me and said that he had a breech plug for a NEF that he designed. He was using this plug in his and his sons rifles. It was a one piece plug, but the only problem was it was of the newer 5/8" variety. My two NEF rifles used the 7/8" thread. So I was on a quest to find me a NEF Sidekick with the 5/8" breech plug, and aquired one. Nick sent me a plug to try, as I was dying to find a plug that I coud just pop a primer in, no muss and no fuss. The plug came and I couldn't wait to test it out with Blackhorn 209. This plug also headspaced off the rim of the primer, so I was concerned that I might still have some blowback with BH209. But first I wanted to conduct some primer tests without a load.
I fired it with a primer and knew I would have to tweek it a bit if I wanted to seal out blowback. I then did some measuring and came to the conclusion that I could utilize my o-ring modification in this plug as well. This would help seal the ignition, while providing maximum flame and pressure for ignition.
Here is a unfired primer, primer fired with my o-ring mod, and a primer fired without the o-ring mod.
This is an unscientific experiment I conducted over a year ago. I fired two primer through the plug approximately a foot from the snow. Primer with o-ring on left, without on right.
Early prototype MU plug, with my o-ring mod in the primer pocket. DONT LOOK LARRY!
Production plug.
Breech after a range session.
I am running out of time, but to make a long story short. I contacted Nick with my findings and he liked it as well. I was ecstatic when he said he would make the 7/8" plugs, and tried to help as much as I could with that project.
Gotta run! (to be continued)