Please feel free to speculate on accuracy quirk with 3/4 full case for Fire Forming

[PigButtons]

I have a thing for 22K Hornet single shot rifles and Fire Forming is not something I enjoy much but I've gotten much better and seldom crack cases anymore.

Usually I use a reduced load that only 3/4 fills the case and had always heard that it was important to point the rifle up before firing to make sure that the powder was as close to the flash hole as possible to minimize flash over and detonation. Well I got a little lax and didn't tilt the rifle and with my single shots the round is pointed slightly down when loading on the bench. I did it twice in a row and not only did it not crack the case, it put both rounds through the same hole. I then tried it again and then in another rifle and every time the rounds loaded pointing down before firing had better accuracy than those tilted up. Still no cracked necks. Early on I did confirm that if the powder is evenly distributed horizontally so that the air gap runs the length of the case it can cause detonation and crack the necks.

So what do you suppose is going on that the air gap at the primer end is more accurate than the gap at the bullet end? Or am I just over thinking the whole thing.

 

[JohnKielly]

It could be that the primer flash gets to light a greater surface of powder & does so more efficiently. Of course, the result on paper might be just coincidence.

 

[PigButtons]

It could be that the primer flash gets to light a greater surface of powder & does so more efficiently. Of course, the result on paper might be just coincidence.

Thanks, that's some pretty good speculation for what must be like 4am down under. And on Sunday no less.

 

[snert]

Not first hand disclaimer: This is NOT first hand experience!

One of the accuracy challenges with a Hornet is the thin neck. it provides very little consistent tension. Long ago the Rem 6 1/2 primer was the "thing" for Hornets. Conjecture was that the milder pop allowed the powder to start its burn before the bullet moved due to the harsh pop from hotter primers. So in essence, a milder primer allowed for a more efficient burn, as the bullet remained in the neck a "scooch" longer. Yes, that is a scientific term.

Possible that you are having a similar effect from the powder being forward? or maybe the Red Gods are just messing with you, trying to get you to swing the gun around three times over your head before shooting, to repeat that one hole group! (We will do just about anything to repeat such anomalies

 

[dannyjbiggs]

And on Sunday no less.

This is Saturday?!

 

[PigButtons]

This is Saturday?!

The poster JohnKielly is in Australia, they are a approximately 14 hours ahead of the US.

 

[PigButtons]

Not first hand disclaimer: This is NOT first hand experience!

One of the accuracy challenges with a Hornet is the thin neck. it provides very little consistent tension. Long ago the Rem 6 1/2 primer was the "thing" for Hornets. Conjecture was that the milder pop allowed the powder to start its burn before the bullet moved due to the harsh pop from hotter primers. So in essence, a milder primer allowed for a more efficient burn, as the bullet remained in the neck a "scooch" longer. Yes, that is a scientific term.

Possible that you are having a similar effect from the powder being forward? or maybe the Red Gods are just messing with you, trying to get you to swing the gun around three times over your head before shooting, to repeat that one hole group! (We will do just about anything to repeat such anomalies

Let me see if I understood you correctly, having that air gap at the flash hole gives the primer's flash some space to expand into so that it doesn't prematurely push the bullet from the neck. I like that idea. Sure beats having to always carry a chicken's foot in my left pocket
Bye the way, who's the guy with the Creedmore talisman? Maybe we should get his thoughts

 

[dellet]

There have been a lot of tests done over the years dating back to the introduction of smokeless powders. Some of the early ones were trying to figure out why shotguns of the day often had bulged or burst barrels.

Shooters using smokeless loads in Black powder cartridges debate the subject of powder column placement, wads and fillers pretty aggressively. More so if antique barrels are being used. The lower carbon content makes for a weaker chamber and are more easily damaged. Barrel ringing, where a ring is literally pounded into the chamber over time at the base of the bullet, is real problem. To the point that a case can be hard, if not impossible to extract.

Charles Dell devoted a chapter to the issue in “The Modern Schuetzen Rifle” about 30 years ago and is often referenced in these discussion.

If I understand the basics correctly, in a reduced load (keep in mind what he experimented with were generally less than 50%) you end up with a gas column forming ahead of the powder charge that ends up being compressed by a second column of gas and powder. This creates a sort of ring of higher pressure

One of the experiments that is claimed as proof of this was the same charge in a test barrel fired both straight up and also straight down. The shots fired straight up resulted in split cases and a ring in the chamber. Those fired straight down had no adverse effect.

These tests were done in a barrel designed to be basically no more than something to hold a replaceable chamber that was made from a softer material to more duplicate the older barrel steel. If I remember correctly, the ringing could not be duplicated in modern barrel steel.

What you could do is next time you fire form, set up the chronograph. The numbers might just confirm more stable ignition and combustion with the powder forward.

 

[PigButtons]

There have been a lot of tests done over the years dating back to the introduction of smokeless powders. Some of the early ones were trying to figure out why shotguns of the day often had bulged or burst barrels.

Shooters using smokeless loads in Black powder cartridges debate the subject of powder column placement, wads and fillers pretty aggressively. More so if antique barrels are being used. The lower carbon content makes for a weaker chamber and are more easily damaged. Barrel ringing, where a ring is literally pounded into the chamber over time at the base of the bullet, is real problem. To the point that a case can be hard, if not impossible to extract.

Charles Dell devoted a chapter to the issue in “The Modern Schuetzen Rifle” about 30 years ago and is often referenced in these discussion.

If I understand the basics correctly, in a reduced load (keep in mind what he experimented with were generally less than 50%) you end up with a gas column forming ahead of the powder charge that ends up being compressed by a second column of gas and powder. This creates a sort of ring of higher pressure

One of the experiments that is claimed as proof of this was the same charge in a test barrel fired both straight up and also straight down. The shots fired straight up resulted in split cases and a ring in the chamber. Those fired straight down had no adverse effect.

These tests were done in a barrel designed to be basically no more than something to hold a replaceable chamber that was made from a softer material to more duplicate the older barrel steel. If I remember correctly, the ringing could not be duplicated in modern barrel steel.

What you could do is next time you fire form, set up the chronograph. The numbers might just confirm more stable ignition and combustion with the powder forward.

Thank you so much for taking the time to respond. It is an awesome example of the vast knowledge base here on AS and very good information to have.

 

[PopCharlie]

Not first hand disclaimer: This is NOT first hand experience!

One of the accuracy challenges with a Hornet is the thin neck. it provides very little consistent tension. Long ago the Rem 6 1/2 primer was the "thing" for Hornets. Conjecture was that the milder pop allowed the powder to start its burn before the bullet moved due to the harsh pop from hotter primers. So in essence, a milder primer allowed for a more efficient burn, as the bullet remained in the neck a "scooch" longer. Yes, that is a scientific term.

Possible that you are having a similar effect from the powder being forward? or maybe the Red Gods are just messing with you, trying to get you to swing the gun around three times over your head before shooting, to repeat that one hole group! (We will do just about anything to repeat such anomalies

3 times? I thought it was 4 times.....damn.....no wonder I can't get anything to group.
PopCharlie

 

[jelenko]

Right. And the term is actually 'smidgen', not 'scooch'. I've heard that using 'scooch' will cause some results to be not accurate.

 

[snert]

Let me see if I understood you correctly, having that air gap at the flash hole gives the primer's flash some space to expand into so that it doesn't prematurely push the bullet from the neck. I like that idea. Sure beats having to always carry a chicken's foot in my left pocket
Bye the way, who's the guy with the Creedmore talisman? Maybe we should get his thoughts

Mic McPherson did a whole write up on this topic years ago in PS. My memory is full of holes, so don't quote me. I've been known to mix things together...like The Gettysburg address and The Duke in Hondo...Sure keeps things entertaining. But basically I remember that his conclusions were that the primer was moving the bullet (inconsistently) prior to full ignition.