"If all else is equal" component question...

[Skychief]

I am wondering about pressure (and subsequent velocity) of a variable in an otherwise identical shotload.

If one uses a tight fitting over powder "nitro" card and gets 'X' pressure/velocity.......

......What can be expected from using one tight fitting over SHOT card atop the powder charge in terms of pressure/velocity?

What if one uses just a tight fitting cushion wad atop the powder charge?

Assume all else in the load is equal.

Thanks for your thoughts, Skychief


PS: I want to think that a load with a thin overshot card or just a cushion wad wont seal as well as an over powder "nitro" card and develop less pressure/velocity as a result.

Don't let my suspicions skew YOUR thinking as I may be all wet. Possibly any of the 3 will seal as well as the others.

Maybe someone has tried this variable out over a chronograph. :idunno:


thanks again for sharing your thoughts! :thumbsup:

 

[dbutch]

Here's a link...bite the bullet...ERR... round ball and go for it! recomend the pro chrono and give us your results
I call it a de-liar!




http://www.midwayusa.com/find?&newcategorydimensionid=4023

 

[Skychief]

Dan, you know how lazy I am. Are you serious? :haha:

 

[Loyalist Dave]

A follow-up question...., so you think that using a tighter fitting wad will give a split second delay longer than other wads, and so deliver more velocity.

OK assuming this hypothesis is correct..., and that shot column sits still for just a second before the increased pressure slaps it in the arse and makes it move forward..., could the delay that causes the pressure to build a bit more also be causing a greater jump from zero to muzzle velocity, and achieve that jump in a shorter time, thus possibly causing more shot deformation? I mean if instead of a push by the powder charge the shot column gets more of a punch by the powder charge?? Might that not cause more deformation of the pellets??

LD

 

[BrownBear]

I figure there's about a thousand shots and pellet counts between you and your answer, by the time you do each variable at least 10 times for averages.

Better get started! :blah:

 

[dbutch]

Dan, you know how lazy I am. Are you serious? :haha:

I'm thinking "frugal"

These things will tell you more than you thought....and if "big if" you go that route we could compare notes! It's a small price to pay for the knowledge gained...

 

[roundball]

Always interesting to explore...hope we're not over-thinking things though.
The goals are pattern / penetration / distance for the game (or clay target) that we're after.

We use different powder granulations like 2F or 3F which have different burn rates / pressure spikes/curves to get the patterns and performance we need to achieve those goals.
Once the goals are achieved, whatever the specific FPS velocity is or is not...whether there are a half dozen more deformed pellets or not...basically become moot points...ie: the goals were achieved.

There may be circumstances where nirto cards provide benefit, don't know...personally, I've never found a benefit for a hard nitro card.
Depending on gauge and goals, I either just use a pair of Oxyoke 1/8" prelubed wool wads...or, one full Circle Fly 1/2" cushion wad.
For me, if patterns are good, turkeys drop where they stand, squirrels drop out of trees...the goals were achieved.

 

[BrownBear]

For me, if patterns are good, turkeys drop where they stand, squirrels drop out of trees...the goals were achieved.

That's it. When something works, I quit screwing with holes in paper and go back to the hunting I prefer. More holes in paper are pointless.

I've found that field time invested in researching better hunting tactics results in more game than time and money spent at the range chasing statistics.

 

[Stumpkiller]

Trouble with testing in hunting situations is you have too many variables. Very seldom would you have two identical shots at game. You look at two results, but did #1 drop because of a lucky pellet or was the animal at a broadside vs. quarter facing away, was there underbrush in the way, was the wind from behind or the side, did I estimate the raange correctly, did it move/fly/run into the shot, etc., etc.?

I solve this by putting in a "scooch" of extra pellets to nullify the unfavorable variables and gun demons and just shoot away. :haha:

 

[Skychief]

A follow-up question...., so you think that using a tighter fitting wad will give a split second delay longer than other wads, and so deliver more velocity.

OK assuming this hypothesis is correct..., and that shot column sits still for just a second before the increased pressure slaps it in the arse and makes it move forward..., could the delay that causes the pressure to build a bit more also be causing a greater jump from zero to muzzle velocity, and achieve that jump in a shorter time, thus possibly causing more shot deformation? I mean if instead of a push by the powder charge the shot column gets more of a punch by the powder charge?? Might that not cause more deformation of the pellets??

LD

While I may think a tighter wadding system may give higher pressures (in fact I am sure it would have to, for laws of physics), that has little or nothing to do with my original post.

Remember we were to assume that each card or wad was tight fitting to begin with (a constant).

The difference between them is their density, physical makeup and bearing on the bore wall (thickness).

My wonder and suspicion is that a "nitro" card would provide for a better seal as it is denser than a cushion wad and has more bearing and is more rigid than an overshot card.

I readily admit that if any differences are real, they might be so small as to be insignificant while hunting. My question here was made in an attempt to get some feedback to ponder simplifying my load chains.

If the necessary seal (and resulting pressure and velocity....i.e- penetration) can be had with just cushion wads, for instance, I don't know why I would continue nitro card use. This assumes I can keep away from the maddening donut-hole patterns my gun loves to throw with cushion wads (but that's a different discussion and something I have been working on).

I do have a hard time believing that (with all else equal) a cushion wad alone will provide the same penetration as a nitro card alone (or overshot card).

That is my wonder. That is the question. While it could very well be a moot point, that is the question. If any difference is negligible ....all the better, as more viable possibilities will be open to my hunting loads.

The setback of a shot charge is not a concern to me in regards to this thread.

Thanks for your thoughts everybody, Skychief.

PS, you are right Dan, I am cheap, er, frugal. :haha:

 

[Joel/Calgary]

Obturation of the bore appears to be a function of both "tightess" and thickness, even in the absence of consideration of bore conditions. Most who've given specifics on using loose traditional materials like tow, moss, or wadded paper seemed to be consistent in needing enough material to pack down to ~1/2". V.M. Starr recommended two cards punched from 3/32" cardboard. "Iron Jim" Rackham of this forum found that two of the nominally .025" over-shot cards worked for him, and many others here have gone to this system.

I've gone away from the 1/8" hard "nitro" over-powder cards, as they do seem to negatively affect my patterns in the absence of chokes. My impression is that these were an outgrowth of the early cartridge loading technologies, rather than of muzzle-loading, anyway.

My 16ga double has somewhat rough bores, and recovered paper or light-card-stock shot protectors will show distinctive brown burn streaks if there is blow-by. For an over-powder seal for normal loads, a minimum aggregate card thickness of at least 5/64" (.0769) or preferably 3/32" (.09375) seems needed.

For reference, these are my notes on the thicknesses of various materials I've mic'd, and the combined thicknesses of multiples of them. The thicknesses are as many do for measuring cloth for patches: "clicker" tight / finger-snug compressed:
- waxed milk carton: .0190/.0183 (4=.076; 5=.095)
- various cereal and cracker boxes chosen by feel (smooth printed exterior over unbleached brown and various medium-smooth interior finishes): .024-.026 / .0190-.0217 (avg ~ .0230(click) => 3=.069; 4=.092)
- stiff green pressboard folder: .025
- stiff grey 25-pt. grey pressboard dividers (Oxford A-Z File Guide Set, No. 1025): nominally .025 => .0238/.0235 (3=.0714; 4=.0952)
- nominal .025 Circle-Fly over-shot cards: avg. .0288/.0275 (3=.0864)
- nominal .125 Circle-Fly over-powder "nitro" cards: .1345/.1254

Regards,
Joel

 

[Skychief]

Thanks Joel.

 

[tg]

i would think the os card being muxch thinner could deforem and cause a loss of seal but have no idea what % one is talking about, it seems that it would be hard to test any combo of cards/wads as getting the exact same fit/pressure configuration to start would be next to impossible and tis direction of analysys is kind of over the top as to having any meaningfull results for the average useage of MLs, no flame intended here towards anyone, just that there are many times in this sport that as far as analyzing, testing and heavy thinking, less is probably better, the "testing theories syndrome" is probably just a carry over from the modern high tech centerfire R&D concepts we all grew up reading about and buying into, much of which was more to the benifit of the accessory vendors and gun manufactures than shooters in the long run if one were to look behind the curtain. :idunno:

 

[Skychief]

Your point is very well taken tg. :thumbsup:

 

[Joel/Calgary]

I should have mentioned that the 25-point pressboard (=.025"; one "point" = 1/1000" in these matters) is quite stiff and smooth, and is much like the material of commercial over-shot cards. It is a common material for dividers, folders and such in office use, and is my preferred material for making over-shot card wads.

I should also mention my experience in that other somewhat controversial aspect of wadding producing blown patterns in unchoked guns. I too found that lube-saturated (in this case, Crisco) 1/2" cushion wads produced blown patterns, and even saturated 1/4" ones, which I could find completely shredded on the snow for several yards in front of my firing position, produced unevenness in patterns that disappeared when I switched to lightly-oiled felt cushions. With its rough bores, my 16ga NEEDS adequate lubrication to keep fouling under control, but I haven't made the time lately for the pattern-testing to rigorously examine the alternatives in lighter-weight lubed-cushion wads. This is all loading the cushion over multiple o/s cards for an over-powder seal. I have used spritzing down the barrel, too, but I'm trying to minimize the number of steps as well as the amount of STUFF that I use in the field, while keeping at least somewhat in the spirit, if not the letter, of the old ways.

Regards,
Joel