CVA Hex Breechplug Modification

Last night i installed a vent liner into a CVA hex head breech plug. The job was not done the way i have done dozens and dozens of others. In this case an attempt was made to install a vent liner using minimal tools. The method used was a first for me. A machinist would not do the installation in this fashion. A pianist might or perhaps a pharmacist, or carpenter would use this method. First step was to make some sort of a jig to hold the plug centered under the drill press. This block of wood has a mortice chiseled into it so a 12mm wrench can be used to keep the breech plug from spinning.





The block was clamped to the drill press, and a 5/8" hole drilled.






Then the plug was dropped into the hole, a 5/32" was chucked, lube was applied, and a 5/32" hole was drilled all the way through the plug.










Then the 5/32" drill was replaced by a # 4 1/2 eighty two degree center drill; the drill was lowered until it contacted the plug, and the depth gauge on the drill press set to 3/8".









The center drill then was used to drill a 3/8" diameter hole 3/8" deep in the end of the breech plug.







The belts were disconnected on the drill press, the center drill removed, and a 10-32 tap was chucked.







The vent to be installed has about 6 thread.





The chuck was marked with the blue line so rotations could be counted whilst threading the plug. Eight rotations were made to insure the vent would fully seat.

Can a modified plug be purchased or...

is this only a DIY fix.

I bought a very nice CVA Optima Pro 50cal and really want to shoot BH209 but after reading up on the powder I'm concerned about the hang fires due to the breech plug. This Mod appears to be the best solution if one can get a modified plug.

Thanks for any info - Big Bill

This modification was mostly developed to make the CVA rifles reliable with BH 209. It has never never failed to ignite BH in my rifles in temperatures as low as -13 degrees. It works unfailingly to my knowledge. There are dozens and dozens and dozens of folk shooting BH in their CVA rifles using a plug modified like this; no one has ever reported a failure.

From your post, it is my impression you wish to purchase a plug so modified. If so, i suggest you mail me your plug, and i will modify it for you. I won't do it for free, because i don't want to be deluged with plugs needing modification; i am retired. Time is the most precious thing available to me now, and i don't wish to be tied up working breech plugs, when i could be using breech plugs to make smoke.

Excellent.

I too am now retired and will add that along with grandchildren, time is "the most precious thing available" and appreciate your offer to share some of yours to do the mod.

One question... how long will a vent liner last... in shots. Are they something I can buy to have a spare or 2?

I may will email you later for your mailing address to just send the $. I'm thinking if I do this I would just purchase a new plug and have it drop shipped to you.

Thanks,

Bill

Vent liners can be purchased from Lehigh Bullets, Precision Rifle, and Savage Arms. From one vent liner, one should be able to get 200 shots or more, or less; i don't know.

is this a better design than the replacement plug from cva that is made for BH209?i ask because i bought one and changed the plug out first thing before ever shooting my rifle.i have never even used the stock breech plug that came with the rifle.

ellerja said:

is this a better design than the replacement plug from cva that is made for BH209?i ask because i bought one and changed the plug out first thing before ever shooting my rifle.i have never even used the stock breech plug that came with the rifle.

Click to expand...

The plug shown being modified in this thread is for use in the pre-2010 CVA rifle. The BH209 plug you purchased is for use in the new model CVA rifle. They are not interchangeable.




The OEM breech plug that came with your rifle can be modified so it will be 100% reliable igniting BH.











Whether the modified QRBP is better than the made for BH209 plug is a matter of opinion.

Some believe it is. Some like the removable vent which the modified plug has. When the flash hole erodes, the vent can be replaced. The flame channel of the modified QRBP is longer, and wider, than the flame channel of the made for BH QRBP. This allows for more shots, before it plugs with carbon, and may reduce the pressure on the nose of the primer, because the larger volume acts like an 'expansion chamber'. To clean the modified plug, one simply removes the vent, and run a powered drill in, through, and out of the plug. The made for BH plug require a special drill with a 60 degree taper, which is to be turned by hand, to remove the carbon from the flame channel. One 'judges' whether the juncture of the flame channel and flash hole is carbon free. There is no doubt when cleaning the modified plug; the end of the vent can be seen, whilst holding it in hand, outside the plug.

The critical measurements of the made for BH209 QRBP, are virtually identical to the measurements of the standard TC Omega/Encore plug, so, one can 'know', it will be reliable igniting BH.

The old style Optima Plug along with the Accura Plug you made me for the .45 MAG HUNTER works great with BH-209. THANKS

do you modify the new QRBP the same way?

yes

I sent you a pm for this man!