About leade lenght after 2 cup of morning coffee

[Timo]

There is going on other thread about leade lenght and I dont disturb it. I write few things looking this from 22 LR ammo side.
Maybe partly repetition what I have wrote before,but maybe good one to thinking of leade lenght and ammo.

My thoughts:

If we dont have exact straight chamber maybe then we get better accuracy with smaller engraving.

But in nowadays 22 LR ammo we have too much primer force and this prefer bigger engraving.

Primer mass work is explosion and powder work is burning.

Primer force is hitting bullet moving and then if primer force is changing, space to powder burning in the beginning is changing.

Static friction is bigger than kinetic friction and what more engraving, more resistance to bullet moving to primer force hit.

Gunsmiths are changing leade lenght of chamber.I am playing changing ammo lenght from bullet shoukder to case end.And also the bullets surface lenghts.

Long time ago I noticed that when powder is located near the bullet in 22 LR ammo, I got smaller V3 speed spread.Scratching my head and I cant find other explanations that primer flame is "better" when going 0,4" + than less.
Also I was thinking that is it possible that powder near the bullet is working better "shock absorber" against the primer force hit.(Maybe my too strong imagination).
Made different "mediums" to cases and tried to block or make smaller this primer force hit.

But when we find excellent lot without fliers then it is waste of time to try to make it better.Just shoot and enjoy.

One common outside property to good lot is constant lenght from bullet shoulder to case end. But this dont help if lots primer force is changing, cases hartness (neck tension) or bullets outdrawing force is changing.

I havent changed my mind. This is "ammo from hell".

BR, Timo

 

[RWF1]

I’ve been lurking here since my purchase of an old Flash Turbo last year. This post reminded me again I needed to register so I could add thoughts relative to this subject. So, thanks for letting me join!! Allot of knowledge passed around here..

Your findings on powder position is very interesting and since these cartridges are not filled with powder it makes allot of sense that powder position could affect ignition.
Something else I’ve noted may be relative to this conversation. Over the winter I pulled random rounds from a specific lot # of Lapua Midas+ that had performed poorly in my gun. When pulling the bullets and pouring out the powder to measure I found broken up primer paste (Lapua uses a red colored formula) mixed in the powder in many of the rounds. This, I would imagine, could cause ignition variances that would be very difficult to manage/detect. I can only assume that the manufacturer would take precautions to insure this is controlled but how the ammo is handled after it leaves them is totally uncontrollable. I can only imagine how these cases of ammo are jostled around before they reach the user. Obviously you can’t break a cartridge open before use so you’re stuck with what you got. Unfortunately, this could lead you to believe a specific Lot# is bad and you would avoid using it when in reality it may be a couple of specific cases of the lot that got dropped off the back of the delivery truck or fell From a loose pallet or, or, or…. This Rimfire game is a fickle one!!!

 

[Tony K Harper]

I’ve been lurking here since my purchase of an old Flash Turbo last year. This post reminded me again I needed to register so I could add thoughts relative to this subject. So, thanks for letting me join!! Allot of knowledge passed around here..

Your findings on powder position is very interesting and since these cartridges are not filled with powder it makes allot of sense that powder position could affect ignition.
Something else I’ve noted may be relative to this conversation. Over the winter I pulled random rounds from a specific lot # of Lapua Midas+ that had performed poorly in my gun. When pulling the bullets and pouring out the powder to measure I found broken up primer paste (Lapua uses a red colored formula) mixed in the powder in many of the rounds. This, I would imagine, could cause ignition variances that would be very difficult to manage/detect. I can only assume that the manufacturer would take precautions to insure this is controlled but how the ammo is handled after it leaves them is totally uncontrollable. I can only imagine how these cases of ammo are jostled around before they reach the user. Obviously you can’t break a cartridge open before use so you’re stuck with what you got. Unfortunately, this could lead you to believe a specific Lot# is bad and you would avoid using it when in reality it may be a couple of specific cases of the lot that got dropped off the back of the delivery truck or fell From a loose pallet or, or, or…. This Rimfire game is a fickle one!!!

RWF1,

I've seen the same thing in eley rounds. Here are a couple of pics. If you look at the one showing the inside of the case, you can see a shiny spot at the lower left. That is where the primer was missing. That orange speck is a piece of the primer. This round failed to fire that it why I pulled the bullet. I guess I should be glad it did. Could have cost me a match.

TKH

 

[RWF1]

RWF1,

I've seen the same thing in eley rounds. Here are a couple of pics. If you look at the one showing the inside of the case, you can see a shiny spot at the lower left. That is where the primer was missing. That orange speck is a piece of the primer. This round failed to fire that it why I pulled the bullet. I guess I should be glad it did. Could have cost me a match.

TKH

Exactly what I’ve seen, sometimes worse!!

 

[Timo]

Gunsmiths have choiced small leade angle to RFBR chambers long time (1,5-2,5 degrees mostly).Decades.Also very smooth surface to leade.

If you think again this from ammo side. Small leade angle gives bigger static friction area to bullets and it is good one against primer mass strike.

Smooth leade surface is not making friction bigger but it gives constant to bullet going over in the beginning.

Smokeless powder burning is VERY sensitive to pressure where it is and if this primer mass hit makes burning volume different from hit to hit in the beginning, Houston we have a problem.

Everybody can see this when shoot first shot after barrel cleaning to chrono. Common first shot speed is 1120-1140 feet/s and next one is then normal 1060-1070 feet/s or so.
Barrel without wax has bigger friction to bullet, pressure behind bullet goes up and smokeless powder burn then faster.

I have played with different waxes.My friend said me one time that put pine pitch to bullets and you get better powder burning...I said to him that otherwise good one but we are mostly looking slower ammo to smaller wind drift.

BR,

Timo