Author Topic: Enlarged vent hole?  (Read 4105 times)

Offline P.W.Berkuta

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Enlarged vent hole?
« on: February 25, 2010, 06:57:18 PM »
My question is this  - I was asked by a lady from my club to look at her flinter because it was "chewing" up flints and "spitting" particles at her and others. I solved the flint "chewing" but she still has the "spitting" issue. She is bringing it over this weekend and my first thought is that the vent is oversized and allowing a large amount of gasses to escape. In any event I plan to install a Chambers vent liner - what do you all say ?????
"The person who says it cannot be done should not interrupt the person who is doing it." - Chinese proverb

Offline Roger Fisher

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Re: Enlarged vent hole?
« Reply #1 on: February 25, 2010, 07:11:42 PM »
A flash guard would be an easier fix for her blasting the folks on her lock side and they would like her more... ;D

Is this young lady being too aggressive with her vent pick?? Meaning is she grinding the vent larger by using a roughened vent oick?  Been there and done that ::)  Has she been missing with low shots??  Has she been increasing her powder charge due to shooting low??  Generally a 5/64 th vent opening is about right - no larger please.... many shooters stay just a hair over 1/16th.  :)

Offline P.W.Berkuta

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Re: Enlarged vent hole?
« Reply #2 on: February 25, 2010, 11:00:14 PM »
I will ask her these questions and take some measurements of the vent hole when I see her on Sat --- thanks Roger.
"The person who says it cannot be done should not interrupt the person who is doing it." - Chinese proverb

Offline SCLoyalist

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Re: Enlarged vent hole?
« Reply #3 on: February 25, 2010, 11:37:34 PM »
A White Lightning vent liner might improve ignition time even if a flashguard solves the 'spitting' problem.  Why not do both?

SCL

William Worth

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Re: Enlarged vent hole?
« Reply #4 on: February 25, 2010, 11:41:01 PM »
...but I would still install the Chambers White Lightning Liner.  Not that it helps flints or stops flash ejecta.   They just ignite & shoot more better with them.

ottawa

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Re: Enlarged vent hole?
« Reply #5 on: February 26, 2010, 02:20:07 PM »
the guard seem the way to go about the spitting most places suggest you use one if you shoot on line with others and most reenacting groups require it

northmn

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Re: Enlarged vent hole?
« Reply #6 on: February 26, 2010, 02:32:55 PM »
I ahve done some chronographing and hold to a theory that vent size also should depend some on caliber.  There have been some that fell that as vent sizes increase due to things like burning out from shooting or over aggressive picking with the wrong tools that accuracy suffers, again a theory.  I use a wire gauge size just under 1/16" for my 25, 50 wire gauge (.070)? for medium bores and go up to 5/64 for the 12 bore. I feel there is a reasonable ratio of bore size to vent, again a theory.  Larger vents do decrease velocity, as I found in my 54, but not so much as to negate reliability for a hunting arm.  A 070 vent gave about 30 fps less velocity than a 1/16 in my 54, maybe.  There are many factores that go into ignition including vent placement.  Not so critical on a target arm as you can prime to the bottom of the hole, but on a hunting arm, while carrying, you need to make sure that priming cannot filter into the touch hole and yet have positive ignition.  Nothing wrong with installing a WL.

DP

Offline P.W.Berkuta

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Re: Enlarged vent hole?
« Reply #7 on: February 26, 2010, 07:32:26 PM »
Thanks all for the reply - I know it is a .40 cal - she picks with a copper pick - both her and the shooter on her right get "spitted on" (she wears a brimmed hat when she shoots) - the lock is a older M/G. I do plan on installing a White Lightning liner - thanks all -- Paul ;).
"The person who says it cannot be done should not interrupt the person who is doing it." - Chinese proverb

Daryl

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Re: Enlarged vent hole?
« Reply #8 on: February 27, 2010, 05:33:15 PM »
Some locks spit back into the shooter's head due to the forward stop angle of the frizzen - positioning the frizzen's base at a 90 degree or more angle to the shooter's head. This bounces particles back at the shooter, no matter what.  changing the angle with a 'stop' soldered to the frizzen's tang might help if that's the problem.
Pivot the frizzen back to it's stop position on the feather spring and look at the angle of it's base in relation to the shooter's head.

Candle Snuffer

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Re: Enlarged vent hole?
« Reply #9 on: March 01, 2010, 05:26:52 AM »
I ahve done some chronographing and hold to a theory that vent size also should depend some on caliber.  There have been some that fell that as vent sizes increase due to things like burning out from shooting or over aggressive picking with the wrong tools that accuracy suffers, again a theory.  I use a wire gauge size just under 1/16" for my 25, 50 wire gauge (.070)? for medium bores and go up to 5/64 for the 12 bore. I feel there is a reasonable ratio of bore size to vent, again a theory.  Larger vents do decrease velocity, as I found in my 54, but not so much as to negate reliability for a hunting arm.  A 070 vent gave about 30 fps less velocity than a 1/16 in my 54, maybe.  There are many factores that go into ignition including vent placement.  Not so critical on a target arm as you can prime to the bottom of the hole, but on a hunting arm, while carrying, you need to make sure that priming cannot filter into the touch hole and yet have positive ignition.  Nothing wrong with installing a WL.

DP

Just wanted to touch on DP's reply and add that I use to use a 5/64ths vent hole with my .45 then replaced the vent liner with a new one and did not enlarge the hole like I normally was doing.

By not enlarging the vent hole to 5/64ths - it seemed as if I got better ignition and I know I got better accuracy then anytime before.  Just thought I'd throw this out there.
« Last Edit: March 01, 2010, 05:29:24 AM by Candle Snuffer »

Daryl

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Re: Enlarged vent hole?
« Reply #10 on: March 01, 2010, 07:25:04 AM »
Taylor and I have stopped opening up vent holes as well. We used to open them from the normal approximate .056" to .069" to .070" - not any more.  Once they get to .070" it's time to replace them and that's on our offhand rifles.

My .32 is at about .066" now, but still shot an inch at 50yds. last time out on the target range - maybe 130 shots ago.  We'll have to make a Whitelightning type liner for that one due to not having enough metal to enlarge it for a real W.L. liner. NProb.