Can anybody tell me how the flash hole diameter effects accuracy? When I deburr the flash hole with my Sinclair tool it increases the flash hole diameter slightly. Is this good or bad for accuracy? Or does it have any effect at all?

The increase of diameter is usefull, if we are speaking of the depriming pin, probably not so influent. I'll read again Sinclair Manual written by Gravett and Sinclair.
bye

Hmmmm, how about a tapered flash hole?????

Wow, THAT ought to make a BIG difference!!!

Seriously, though a smaller flash hole supposedly is one ingredient that gave the PPC case an advantage.

Delta, what caliber and degree of accuracy are you talking about? Changes in flash hole size aren't probably gonna make a lot of difference unless you're shooting SOTA guns.

[ 03-28-2003, 22:09: Message edited by: sonofagun ]

Hell Sonofagun - where have you been all your life? Clarinets gave up on a single tapered barrels years ago - once Hans Moennig discovered that double tapering led to a more centred tone. Just remember to tune the note to Bb.

cheers edi

I don't play the clarinet thank you!

Wait a minute! Wait a minute! Maybe listening to clarinet music (key of Bb?) during reloading (or shooting or both - hmmm, more testing) will make a difference, hmmmm...

Maybe tuba music?

"The possibilities are endless!"

Warning Delta - we're hijacking your thread!

[ 03-28-2003, 22:16: Message edited by: sonofagun ]

Well, it sure wouldn't be the first time a thread was hijacked. Since there's nothing I can do to prevent it, I'll just have to tighten my seatbelt and enjoy the ride. Hope you guys don't take us too far off course.

The reason I asked about flash hole size is because I just acquired some RWS brass for my 7mm Rem Mag. I'm pretty sure these are drilled and not punched, so in general the flash holes don't have any burrs. But I've noticed a few do and I wanted to clean these up. In the process, however, the flash holes are enlarged also. This is not a benchrest rifle, but it is capable of fine accuracy and I guess I just wanted to know if there was some general rule of thumb regarding the effect flash hole size has on accuracy.

[ 03-28-2003, 23:03: Message edited by: Delta Hunter ]

Delta Hunter - my apologies. It's been a long week at this end.

On flash holes - I've held a Berdan primed case next to a Boxer case and often wondered about the relative sizes of the flame area vs the cooling effect of the brass walls of the tube. Never came to any startling conclusions. In the "fast" world of explosive combustion, the propellant is up and running before the primer composition has finished flaring through the hole, so I would opine that matching the flash holes, chamfering the edges, tapering or double tapering the hole would show no measureable effect on the rate of pressure rise inside the brass combustion chamber.

Of course all that preparation is good for the soul and helps pass the time from one range day to the next - and I'm guilty as charged.

Actually I think that Dreyse got it right. Place the primer in the base of the bullet and let the combustion burn from the front of the case to the rear. Our mining guys developed electronically timed detonators to control sequential blasting. It's more accurate than relying on the length of blasting fuse.

The electronic boffins love making things ever smaller and cheaper - so design the bullet complete with primer compound and with its own integral electronic ignitor. Resize case, measure the powder into the primer-pocketless case, load bullet. Cartridge ready.

No primer catcher filled with lovely little copper cups with no earthly use.

The trigger sends an electronic signal that sets off the primer compound.

Using a remote encoder you could go so far as to "tune" the ignitor signal that it becomes calibre/case specific. No more blown up actions due to cramming in the wrong cartridge.

You want a tracer - use a special primer with a built in delay - the tracer only comes into life after a preselected distance - so as to maintain accuracy as far downrange as required.

Long range ammo - use a base bleed primer.

Scramble the trigger ignition signal on putting the rifle away and it's useless to anyone.

As I said - it's been a heavy week.

cheers edi

Also add micro-guidance-computer chip in the fusable nose cone of the bullet operated by the computer-laser tracking scope on your rifle.
Built in nano-surgeon imbedded matrix field dresses the game; optional nano-thermonuclear inclusion also cooks filets.

UGLY...thermonuclear erection

Okay, who opened that SECOND jar of whiskey?
D hunter, I have been flamed unmercifully because I use shitty old USA brass that has a punched flash hole rather than high tone (read expensive) foreign brass that has a drilled flash hole. The advantage, they say, is the punched hole leaves a ragged edge and even, god forbid, a little trapdoor that lifts up from the hole. The ragged edge doesn't concern me as it is obvious that these folks have never drilled a hole in a piece of metal. The drilling can leave an edge that is just as ragged as any punched hole. But, the trapdoor does intrigue me. And so, since learning this, I have peeked down hundreds and hundreds of new American made pieces of brass and have yet to see this phenomenom. I am beginning to think it is a fig newton of someone's imagination. Someone that has entirely too much time on their hands.

I think the real advantage to reaming flash holes is to increase the consistency of ignition from shot to shot.

While I primarily use WW brass, I have used Norma as well and always reamed flash holes on both brands. It's a one time operation and certainly cannot hurt. It does however, bolster the shooter's confidence when he/she caresses the trigger.

Regards,

Holmes