Thanks for taking the time to write this up. I actually have that web page bookmarked and saved as a .pdf, which I don't think I post here.

I will try to make it a .jpeg and see if it posts, with proper attribution of course.

In the meantime the entire chart is here: http://www.bunkershooting.com/wadlist.html

 

Oh, thank YOU ~~ someone obviously went back and expanded that chart significantly since the first time I saw it; I see a couple of wads referenced that did not appear in the chart when I printed it out, years ago. Thanks, again!

Wow, even though the footer indicates the chart was last updated 11/13, I thought it perplexing that footnote #9 asserts, "There is currently no loading data published for 24 grams.". They have a very nice photo of the CB-0175-12 wad at the bottom of the page but, they must not have seen the published loads printed on the backside of the label, in each bag of 500 wads . . .

 

OK, so in taking a closer look at this I see that all of the US OEM wads and clones have a gas cup way undersize for the typical US .729"-.730", and would be even more undersized in back-bored or over-bored guns that run .733" or larger. interesting that the SAAMI chamber drawings for 12 gauge show bore diameter at .725" minimum.

The European OEM wads run at or just over the Euro standard .725" and are closer to a better fit in US bores, but still undersize.

All the wads I have looked at are smaller in diameter at the solid top of the gas cup, and have a small but pronounced flare to a larger diameter at the skirt. I know that this flare must expand to fit the bore under gas pressure from behind, and in clear hulls I have seen the skirt expand to seal over the powder just from the pressure of closing the crimp.

So with that said, here are the questions:

1) Why do we so jacked up over using "tapered hull" wads in straight hulls, and vice versa? It seems that they are all somewhat undersized, it's only a matter of degree.

2) What effect does the undersize skirt and cup have on load efficiency and performance?

 

I like this discussion. My Competition Synthetic has a bore that measures .739"/.740", I have measured wads and found that all are smaller that the bore. How much expansion is produced under the pressure of firing? Do all expand to fit and seal correctly? I notice that with similar loads but different wads the bore is either cleaner or not. I notice that with similar loads but different wads the felt recoil and sound is different. A mild Green Dot load with a figure 8 in an STS hull is rather bland 1110fps but the same everything with a SO3 wad is about 1175fps and a great performer. I assume loading data is all based on standard bore sizes? Only in this game a couple years but there is more to this than just pulling the trigger.
I hope you folks keep this discussion going, I feel there is much for me to learn here...... Larry

 

OK, so in taking a closer look at this I see that all of the US OEM wads and clones have a gas cup way undersize for the typical US .729"-.730", and would be even more undersized in back-bored or over-bored guns that run .733" or larger. interesting that the SAAMI chamber drawings for 12 gauge show bore diameter at .725" minimum.

The European OEM wads run at or just over the Euro standard .725" and are closer to a better fit in US bores, but still undersize.

All the wads I have looked at are smaller in diameter at the solid top of the gas cup, and have a small but pronounced flare to a larger diameter at the skirt. I know that this flare must expand to fit the bore under gas pressure from behind, and in clear hulls I have seen the skirt expand to seal over the powder just from the pressure of closing the crimp.

So with that said, here are the questions:

1) Why do we so jacked up over using "tapered hull" wads in straight hulls, and vice versa? It seems that they are all somewhat undersized, it's only a matter of degree.

2) What effect does the undersize skirt and cup have on load efficiency and performance?

I doubt that all this "obturation" takes place instantaneously, and if we use this same logic on metallic loading, then if I had any .270 bullets left over, and I was wanting to load some .284 brass, then all I have to do is crimp the bullet in to stay, it will surely obturate and expand as it hits the grooves of the barrel.

I'm just striving to make the best quality load i can from the git-go. If I miss, it isn't because I didn't do my best at loading, it's cause I'm a pi$$ poor shot.

 

So with that said, here are the questions:

1) Why do we so jacked up over using "tapered hull" wads in straight hulls, and vice versa? It seems that they are all somewhat undersized, it's only a matter of degree.

In a taper'd wall, it's an interference fit, - there is no outward movement of the lip needed at combustion time to make a total air-tight gas seal, - it's instant.

2) What effect does the undersize skirt and cup have on load efficiency and performance?

It's my believe that unless there is a total contact/interference fit of the lip of the powder cup against the hull prior to ignition, that there is always going to be some blowby and flow of gas around the the lip until is flares out (if it does at all) right after ignition. Think "air vane" here. At peak pressure time, this leakage flow is much more significant to the pressure curve signature. Work the equation backwards, and leakage flow at peak pressure makes the effective volume relatively large(er).

Conjecture of course, but think about it in terms of "percentages" (or ratio) of influence after the lip of powder cup exits the hull. At the moment that the powder cup exits the hull, the pressure has dropped by so much (and the acceleration has increased by so much), that the remaining pressure under the powder cup is influencing the already moving ejecta by a much smaller amount (percentage, or "ratio" wise).

Think of the volume delta of the area under the powder cup when fully seated against the powder vs. the volume between the base wad and the powder cup when the powder cup is just ready to exit the top of the hull, - there's at least a 3X increase in volume at that point.

 

And once the wad leaves the hull into the forcing cone there is another rapid increase in volume.

 

And once the wad leaves the hull into the forcing cone there is another rapid increase in volume.

And it's at this point that another sealing effect takes place: The shot setback in the wad pushes the wad petals tightly against the bore, acting as a brake but also sealing the bore along a far longer surface area then any gas cup could offer.

Adding to the unknowns here is the question of how much gas can flow past the wad, almost like a boundary layer effect. I need to fire a load through an absolutely clean barrel and see how much soot and powder residue is on the recovered wad.

It's hard for me to imagine how a short, thin, tapering section of the gas cup skirt that measures .720 can fill a .730 or .740 bore effectively. There has to be some leakage past the gas cup.

 

I doubt that all this "obturation" takes place instantaneously, and if we use this same logic on metallic loading, then if I had any .270 bullets left over, and I was wanting to load some .284 brass, then all I have to do is crimp the bullet in to stay, it will surely obturate and expand as it hits the grooves of the barrel.

If you were using a cast lead bullet and the load generated enough pressure to exceed the yield strength of the alloy you could get away with this, the lead bullet would simply obturate and fill the groove.

A jacketed bullet is too hard. Even though the bullet is engraved by the rifling, I have never seen a load, other than with very thin jacketed .22 caliber varmint bullets, that would have enough pressure to cause a jacketed bullet to obturate that much.

 

I am going to go against the grain here.

I really don't care how large the bore is, the obturating cup will seal, with a properly made wad. Stan Baker's big bore barrels are 0.800" in diameter. Stan recommended Winchester AA and Remington STS/Nitro ammo......the smallest diameter 12 gauge wads!!

Using a wad with a 0.710" diameter obturating cup, it only has to expand 0.0075" on a side to seal in a 0.725" bore and 0.015" on a side to seal in a 0.740" bore. That is not very much expansion, considering the force being applied from the powder side. Like another poster mentioned, normal wad pressure expands the obturating cup against the powder in many loads.

Think about what is going on, when you pull the trigger. In less than a millisecond you go from no gas expansion to enough expanding gas to produce 8 - 9 - 10 - 11,000 PSI and the wad hasn't moved but about 3/4". In about 2 milliseconds the wad base is past the forcing cone, it probably can't even react to the forcing cone and if it does the obturating cup can only expand, providing a better seal.

You must visualize and understand how FAST all this happens.

The only downside to what you folks are considering an undersized wad is possible powder migration and even that is iffy and happens a lot less than you imagine.

I remember this debate, from other threads........most of it is way off base because of a lack of understanding and over the simplification of what really happens when you light off a shotshell.

The following is proof that a supposed undersized wad is capable of very consistent and clean ballistics.

 

I think one can start making arguments on a lot of different peculiarities of our sport. How about the one where everyone claims that little wound paper basewad "soaks up" some of the pressure compared to the plastic basewad hulls. Yeah, it might, but if I ever do reload a paper basewad hull a second time, ya think I'll have dished crimps from the crushed basewad. I doubt it. It is a pretty small area with a pretty large and quick pressure gradient curve, almost vertical. It all goes back to that main saying about our sport, it's 90% psychological. Psychology nor thoughts hit the clay, only shot does, but if we are happy in what we are doing to get there, then we are all arguing for the sake of argument.

Just my opinion, and I remember the old saying about opinions and a$$holes, and no one has to accept my opinion either, unless you come to my reloading room and try to run the show there, then you do. And I would imagine everyone here wold be the same in their play room when others try to take over.

 

oldtechshooter,

Not taking offense to your post and I hope you don't to mine.

Just wondering what you are getting at with your post? Are you commenting that supposed undersize wads are a problem or not? Or are you commenting on the someones post?

You have me confused, for sure. 8)

 

No offense taken Mark. I just brought up the "soaking up" pressure comment as it pertains to that little blow-by issue we are all discussing above, and how psychological it all my actually be. If I or others on the board want their wads to fit as tight as a 13 year old virgin, than that's what I'm gonna do. Does it make that much difference, likely not from what I hear some say. Even the supplier I get stuff from (and a very big shooter) says no, but he only loads full power loads. I do think it might make a difference for those of us who are downloading to light weights in the 12 ga. We can load the same exact weights in 12 and 20 and come out with completely different ballistics, because of the differences in the ga. mostly. These lighter loads in 12 ga. seem to be more sensitive to the 'incorrect' components more than anything else. Is there wad blow by on loose fitting wads, prolly so; is there pressure being "soaked up" by the hard paper base wad, maybe, does it make any difference, might be just in our minds, but the game is 90% psychological isn't it. At these downloaded weights, and getting close to pressures that barely function some autos, I would expect a weaker primer would have more affect, if one was using a recipe for a Fed209A, and didn't have any, but a Winchester or Cheddite was all he had, he might have issues.

I don't leave nuts or bolts loose on my farm equipment, and I don't like loose wads either.

And my comment farther up had nothing to do with your chart at all, but just all of the previous statements related to the OP and tight/loose wads, etc.

 

OK, that makes sense to me, and you are right, most of it is the 6" between our ears. My point was, that loose fitting wads, as long as they are made properly, don't mean squat to performance.

To each his own, have a good one!! 8)

 

Here's a test that you can do to see the performance degradation of an undersized wad/cup:

Add varying layers of various tapes, then load up equal amounts in a Rio hull, then compare the EV/SD/Avg's and pressure (if you have access to pressure measuring equipment) to the figures of the loads with unmodified wads.

I need to fire a load through an absolutely clean barrel and see how much soot and powder residue is on the recovered wad.

You might still be able to detect evidence of a non-sealing wad with a dirty barrel as well. Unrelated to diameter, the first generation of the Claybuster CB6100-12 (on left) wasn't sealing properly at all in SW hulls. All Ron did was to lengthen the lip of the powder cup a bit (and call it the CB6100"A"), and it began working perfectly (on right).

 

. . . All Ron did was to lengthen the lip of the powder cup a bit (and call it the CB6100"A"), and it began working perfectly (on right).

Once again, kudos to Ron & Claybuster!!!

 

Where ignition is instant would the gasses perhaps flow past the sealing lip to some extent before the expansion began and in themselves prevent the full expansion of the lip? The use of the Federal style wad in the STS/Nitro case is a tight enough fit to expand the hull diameter a bit at the base. That should be a great seal and insure maximum pressure and ignition for at least the length of the hull? Larry

 

Where ignition is instant would the gasses perhaps flow past the sealing lip to some extent before the expansion began and in themselves prevent the full expansion of the lip?

In a non-interference fit, it's hard to know what exactly happens prior to the gas seal being made. The fact that the flame front begins in the center (furthest away from the lip) might even mean that building pressure is pushing yet unburned flakes against the void. As long as the void and a pressure gradient exists, there will be some flow.

The question is how much flow, and for how long, and what cost this might have on the pressure peak. Pressure and flow are inversely proportional. Displacement and surface area are also related.

And just because there's 10K psi generated at the peak, that alone doesn't somehow automatically mean that the lip is going to be flared out to create a gas seal. Moreover, if a complete gas seal isn't made before the pressure peak, it's probably unlikely to be made afterwards.

The use of the Federal style wad in the STS/Nitro case is a tight enough fit to expand the hull diameter a bit at the base. That should be a great seal and insure maximum pressure and ignition for at least the length of the hull? Larry

Yes, a pre-ignition gas seal ensures that you'll have a complete gas seal at least throughout the length of the hull.

 

llc,

Here is the problem with all this supposed problem of powder gases leaking past the obturating cup. There is no way to really know how much powder gas is really going by the cup, there is no way to know if once the gasses start blowing by does the pressure equalize and not expand the cup. Someone else offered that the shot load expands the shot cup which seals it, but that is not true, nick the edge of cup and you will hear an off sounding load, because the expanding gas blows right by the shot cup.

All of this is guessing.

First, I would like to offer that Federal wads, which are supposedly undersized' have been around a long time........does anyone really think that Federal doesn't know what they are doing?

Second, I just showed proof that 3 different loads were very consistent with the Federal wads and I have more sheets if you need more proof.

Third, Winchester and Remington wads are smaller in diameter than the Federals and they seal in the bore including the Baker Big Bores of 0.800".

Fourth, this is a non-problem, as long as you are using properly made wads.

Use properly made wads and you won't have a problem with powder migration or sealing the powder gasses. When in doubt use the OEM wads. Some of the after market wads are less than good.

You can prove a good load by using your chronograph and looking for the load to be consistent. 35 FPS max on extreme spread, is reasonable and very easy to achieve.

 

Why does it matter?

Over here we often use fibre wads recipes that have a 4mm thick over powder card pushing the wad up the barrel and gases do bleed up the sides as it is left to the fibre wad expanding against the barrel wall to provide the seal against the pressure. All that happens is that a recipe for a fibre wad load generally has a grain or two more powder to generate more gas/pressure to overcome the losses. Slightly less economical but not really a big deal.

 

FWIW, I believe that all of the OEM wads listed by thor_sen are good stuff, I also have a lot of experience and recommend the CB2100-12 and the CB2118-12 wads, along with all of the Bascheri and Pellagri wads. The B & P wads are similar in diameter to the Gualandi wads.

Here is a link to B & P

http://www.baschieri-pellagri.com/index ... 20&lang=en

 

Mark,
I use Federal wads and clones quite often and my measurements show them to be larger in diameter, not smaller and I am trying a couple loads in Remington hulls that are listed in the Lyman book. My chronograph finds Federal and Duster to be near equal in readings and the figure 8 and WAA choices a bit less for some reason.
I suspect the PROMO and Red Dot I use would need a large gap to migrate and with all my tapered hulls I seat the wad deep enough to make a good interference fit with the internal taper.
You, Republican, Virginian, Cerberus and many others have shortened my learning curve a lot and I do appreciate it. Often as I make observations at the range I am able to diagnose what I see or hear based on information from this site. More often when I hear "gospel" from some folks I shoot with I can bounce it off of my observations and the posts in various threads and make value judgements. Seems though that the more information I have the more questions I have...... Larry

 

llc,

{hs#

 

Seems though that the more information I have the more questions I have......

I always say it like this The more you know, the more you know that you don't really know! :mrgreen: :mrgreen:

 

I use Federal wads and clones quite often and my measurements show them to be larger in diameter, not smaller.

With the exception of the Downrange DRF3 (12S3 clone) which really is smaller:

Whereas the Claybuster 12S3 clone (the CB2118-12), and OEM factory is not:

Using the undersized 12S3 version (or a Tapere'd hull wad) in a Euro hull results in blow-by:

If you must use an undersized wad in a SW hull, use the one with the deepest, and thinnest lip :

Left: blue duster in Fiocchi hull, Right: Downrange DRF3 in Fiocchi hull