Case filler **under** the powder....

[mehavey]

While I've often heard (and even tried) a toilet-paper/plain-paper "dot" over the flashhole in BP cartridges,
never have I heard of anything mores extensive than that... nor of its use in smokeless rounds.
Anyone ever heard of this?
http://forums.accuratereloading.com/eve/forums/a/tpc/f/9421043/m/9481094362



incidentally....
https://www.rockymountaincartridge.com/products.htm

 

[Jim Watson]

That's just weird. He does hardly anything conventionally, but gets good accuracy.

 

[hounddawg]

different for sure. You can't argue with the results.

 

[HiBC]

I recall reading Ned Roberts suggestion for loading BPCR :
A small quantity of coarse powder .perhaps f G or cannon, followed by the main charge of ff G or fff G.

It seemed odd till I thought about it.The coarser powder would allow the ignition flame free travel into the charge,and the larger granules maybe a softer,more consistent start.

i did try a round dot of cigarette paper over the flash hole BPCR.I did not notice anything remarkable,but then, I can't say I went very deep into BPCR.

 

[reddog81]

Primers contain small heavy metal particles that go flying through the powder column. I imagine the primer charge blasts through the TP without much problem. With that said I can’t imagine there’s much of a benefit versus filler being directly under the bullet.

 

[Unclenick]

That's a new one on me. The explanation about the "explosion" effect is nonsense unless you are talking about detonation, which this is definitely not. It sounds like he found a medium just porous enough to let the hot gases get through at a controlled rate. Any other material that affects gas flow-through in a uniform way should work. I would expect some ignition delay to be part of the effect, so your follow-through would need to be good. Very interesting, though, and not something it would have occurred to me to try.

 

[mehavey]

Conflating both the H110/QuickLoad/pressure spike issue in https://thefiringline.com/forums/showthread.php?t=611249 and this one, I noted the comment
that the old BPCR practice of a single piece of toilet paper over the flash-hole/under the powder -- would also serve to keep very fine ball powders out
of that flash-channel and out of the primer itself.

Given I could never understand how the H110 loads in the above thread could
spike to actually expand the entire solid portion of the case head -- "belting"
it so to speak -- I tried it yesterday with the offending LEGEND load previously
mentioned -- but with a single 24-lb inkjet paper 'disk' over the flash-hole.

Ten rounds... each case examined on ejection for even any hint of problem.

Note the use of W296 instead, and even when starting burn rate is adjusted to match a higher velocity we still don't hit MaxP

2,156±08 fps -- extremely consistent -- not even a hint of pressure effects.

But I still don't trust the load. READER TAKE NOTE
*** DO NOT USE ***

 

[Unclenick]

That's really intriguing! Not the loading density but powder in the flash hole adding too much ignition flame to the primer's, or else the paper retarding the flame front some. But it doesn't happen when loading density is higher, and that's pretty odd. Now you have me wondering if the cartridges all rode to the range nose-down to keep the powder out of the primer pocket, would the same thing have happened if you kept the muzzle down and single-loaded?

More information Hodgdon should be made aware of.

 

[HiBC]

In a way this reminds me of something Elmer Keith wrote about.
He used the term "Duplex Load" which may be military disinformation.
Folks,PLEASE do not take the term to mean loading two different powders in a case. Thats an extremely bad idea for a handloader.

The Duplex Load Keith was referring to was about a brass tube from the flash hole to the front of the charge,carrying the primer flame to the front of the charge.

I'm not making any claims for the idea's merits. Its just history.

I'm not telling anyone else what to do.I recall in the 1960's reading about fillers in the powder space. There were a lot of theories about chamber damage.

For myself,fillers in the powder space of smokeless loads is something I just don't do. But you certainly can. If you have an archive collection of John T Amber's "Gun Digest" there were filler test articles.

Weird stuff can happen with low load density and some powders. Reduced loads with surplus H-4831 was an alleged phantom gun wrecker in the 1960's and 70's.

Powder shortages are inspiring some folks trying bizarre experiments with powder to have something that goes "bang"

 

[Unclenick]

Looks like Charles O'Neil patented it here and in Canada around 1930. Look at post #8 in this thread. No clue why he called it "duplex" with no duplex charge or double bullet. IIRC, P.O. Ackley may have played with it, too.