Touchhole diameter and accuracy

[cal44walker]

Are the 2 linked? Just wondering if too large a touchole affects accuracy and if so.........why?

Matt

[Daryl]

Too large a vent will reduce pressure and therefore reduce velocity.  If the velocity is reduced below the 'accuracy' requirement of the rifle, the accuracy will suffer.

ie; as the vent 'wears out', the pressure and therefore velocity gradually drops.  Not only does group size increase, but the point of impact also changes - up or down or perhaps to one side or the other as the barrel's 'whip' changes and releases the ball at a different 'point' of the whip. Yeah, I'd say they are related for sure.

[hanshi]

Hmmm...   I never gave much thought as to the two being related but it makes sense.

[Roger Fisher]

Oh Yeah!   After you drill the vent open from a 1/16 with a slightly larger bit and campher the outside just a frog hair and you go happily on down the road and after a good while (less if you use a roughened pick) you notice she is self priming even with 2 f, you will or should notice some low shots.  Thats when you get another liner and start over again.     By that time a 5/64th will fall in and a 3/32nd darn near!

Been there and done that once or so!

[hanshi]

Mine are all still 1/16" and will pass a 1/16" drill bit but not a 5/64".  I plan to take better care of them in the future but have spares just in case.  I occasionally notice a few kernels of 3f come through but so few I can count them.

[Candle Snuffer]

I shot one of my home made liners out last shoot we had.  My accuracy (if it ever existed) went to he!!...  I noticed the 3fg coming through the vent hole after shooting awhile and knew then the liner was finished.  My accuracy showed that as well.

I finished out the day and after cleaning everything up I installed a new bronze liner.  I had two on hand and wanted to see how the bronze worked.

After everything was good to go, (and I did not enlarge this liner's hole) I threw 30 grains of 3f down the bore and primed the pan.  Boom!  Worked good.  Cleaned everything again and got back to the range in mid-week.  Took 10 shots from 25 yards offhand and was a happy man again.  My accuracy (if we can call it that) had returned.

[hanshi]

Stainless has a superior reputation for standing up to heat & flame.  How does bronze compare to ss in this respect?

[Dphariss]

What I have always heard is that a large vent increases the velocity variation.
Never tested it. Large vent just means more of what you are paying for is going out the vent.
Pressure and maybe even party burned powder.

Dan

[northmn]

One of the things that I think may be related is also the relationship of vent size to caliber.  Many like to use about a .070 vent for reliablility and get good results with a 40.  I question whether that would be as workable with a 32.  As calibers get smaller one sees a tendency to use higher ratio powder charges for accuracy.  If you think about it, the ratio of caliber to vent size increases quite a bit in the small calibers.  What I am saying is that a 5/16 vent in a 58 might be less of an impact than a 1/16 in a 32.  As an aside, I replaced a vent for an individual that thought that 20-25 grains would make a good main charge in a 45 for 25 yard luck match shooting.  It vented the whole charge out the touch hole and the ball stayed put.  Must have had about a 3/32 original vent.

DP 

[Larry Pletcher]

What I have always heard is that a large vent increases the velocity variation.
Never tested it. Large vent just means more of what you are paying for is going out the vent.
Pressure and maybe even party burned powder.

Dan

Dan,
I haven't tested where the purpose was to see if larger vents produced larger variations in velocity, but that may show in data collected for other reasons.  I'll have to look back to see if any stuff supports that idea.

Regards,
Pletch

[Candle Snuffer]

Stainless has a superior reputation for standing up to heat & flame.  How does bronze compare to ss in this respect?

I can't say at this time Flintr, though logic would dictate that the stainless would have the edge. 

[Daryl]

The second Squirrel Rifle Match at Hefley Rendezvous, Taylor and I used Peter's .40 (again) that Taylor built for him many years prior.  Our accuracy was dismal to say the least - we BOTH shoot better than what was showing on the board - same the previous year - same rifle, same poor shooting.  The vent on Peter's .40 had enlarged to the point that as I watched Taylor shove the snug patched ball down the bore, there was a spray of 3F whooshing out the vent.  Hey- that's why some go pop and others crack! - yeah- we're slow.  Merely closing the frizzen during seating, ended up with a full pan of powder - self - priming - too much prime too.  We then plugged the vent while shoving the patched ball down and accuracy returned - too little, too late.

Vent size can make a big difference when the powder can be blown out the vent - some this shot, more next, etc. The vent size might have been around .085" at that time.

[Acer Saccharum]

Sorry if I bore you, because I have said this before, but I know the long range perc guys are VERY fussy about the nipple orifice. They use platinum lined nipples for durability. Any wear causes not only pressure drop, but also increased deviation from shot to shot, which shows up as vertical stringing. At 1000 yds, this is critical.

For me, shooting at beer bottles and woodchucks, a precise touch hole is less of an issue than reliability.

[Candle Snuffer]

I haven't checked around but I think I will.  I'd like to see if platinum vent liners are made?  I'd almost expect that someone is making them, but with the stainless ones available, maybe they're not?  Surely they must be?

I personally learned a valuable lesson in a having a good liner over my homemade jobs.  Not that mine didn't work, and perhaps I went a bit to large on the hole, but when the powder started to show up coming out the hole - I knew it was time for a new one. 

I think had I not saw the powder come out the vent, I'd still be scratching my head.

[Jim Chambers]

The Bevel Brothers use our White Lightnin liners in their chunk guns.  They tell me that accuracy is maintained until the hole enlarges beyond 1/16".  At or below 1/16" they get good accuracy.  Once the hole enlarges beyond 1/16" they change the liner.

[Larry Pletcher]

My experience with LR bullet guns is the same as Acer reported.  A platinum lined nipple is essential when working at the pressure levels a bullet gun uses.  

That said, I'm not sure it is that essential in a round ball gun because the pressures aren't as high.  I could see a situation where a liner is installed such that the web is extreeemly thin.  There one might erode a vent faster.  Properly installed with say a WL liner, I think it would take a lot of shooting to erode one enough to require replacement.  JMHO

Jim,
Have you had any indication from Lowell how many shots they get before swapping?

Regards,
Pletch

[Dphariss]

Sorry if I bore you, because I have said this before, but I know the long range perc guys are VERY fussy about the nipple orifice. They use platinum lined nipples for durability. Any wear causes not only pressure drop, but also increased deviation from shot to shot, which shows up as vertical stringing. At 1000 yds, this is critical.

For me, shooting at beer bottles and woodchucks, a precise touch hole is less of an issue than reliability.

Ahh. But with a good liner you can have both.
I shot 10 rounds with 80 gr of FFG Swiss in the 40 caliber picket gun and its eating the nipple now. 70 grains seemed OK.
Why 80 grains in a 40 some might ask.
Its a picket bullet. Rifles that will shoot 50 grains with a RB may need 80 with a picket.
Just the way the things operate. This comes from the distant past and seems to prove out today.
So I need one of those 30-40$ nipples.
Dan

[Jim Chambers]

Larry,
The Bevel guys say they leave the hole size as it comes from us and shoot until the hole enlarges beyond 1/16".  With the loads they are shooting they shoot approximately 3000 shots before they need to change liners.

[Candle Snuffer]

Larry,
The Bevel guys say they leave the hole size as it comes from us and shoot until the hole enlarges beyond 1/16".  With the loads they are shooting they shoot approximately 3000 shots before they need to change liners.

Couple things Jim...

If I recall what I read in MuzzleBlast in one of the Bevel Brothers articles, if I remember correctly they stated speed was the chunk shooters friend which would lead me to believe they shoot some hefty loads?  This perhaps being the case I think 3000 shots is outstanding for a liner.  

I have never kept track of how many shots I've gotten from other liners, but I'm sure it was nowhere near 3000, nor half that many.

Also, do you offer White Lightning liners in the 5/16x24 made of platinum?

[Jim Chambers]

Unfortunately, I don't think my bank account is large enough to buy the raw material to make platinum liners.  I haven't checked the price of platinum lately, but last I heard it was more than gold which is around $1,000 per oz.  A lot of guys would end up with a touch hole that was worth more than their whole gun.  Ha!
There was a thread sometime last year about making gold lined touch holes.  I assume the same procedure could be used with platinum.  If it could be done that way it would certainly be the less expensive way to go.

[Candle Snuffer]

Thanks Jim, I did not know platinum was so expensive.  I better stick with what I have at this time.

[George F.]

I had a senior moment, and I wasn't a senior yet, I was 45. Somehow I ended up with 4f in my powder horn. Charging the barrel with 40 grains. Well the ball was barely exiting the bore. The touch hole was worn out and all the powder was actually falling out the touch hole before I even fired it. ...Geo.

[duca]

hi all,read a good artical by fred stutzenberger in muzzleblast mag. 1998 were he grinded the flintlock pan with a 1/2 inch ball mill. were he doubled the surface area of the pan. sounds like a good idea. i know this is about vent liners but thought it was in relation to it. im going to try it on a rifle of mine.
.......Anthony.....

[Daryl]

Jeff Tanner makes platinum lined nipples - perhasp give his an e-mail. Only musket nipples are listed on this site, that I saw.

[Darkhorse]

1/16" over a log might be fine but offhand It doesn't work for me with anything over a .40 caliber.
I want reliability and super fast ignition and I drill out one number at a time until I get what I want. I don't see a problem with replacing a WL liner when it needs it.
So what if I get some velocity variation. It affects my accuracy a whole lot less than hangfires and slow ignition while the gun wobbles all over the target.