If you understand that when SAAMI says "pressure", they mean "peak pressure." So sometimes you get more velocity, but it's possible to increase peak pressure with no benefit.
Or you can blow the plastic wad, or burn a hole in the base.. which is rubbish for pattern and velocity as hot gas would then blow through the middle of the shot before it exits the barrel.

 

Mainly the SAAMI guidelines are concerned with keeping shooters safe when using firearms (and their ammunition). Not what the downrange performance of the load will be.

Generally, higher pressures will open shot patterns, other things being equal. Not many folks want to test patterns from loads that exceed the SAAMI guidelines. Higher pressures also result in more recoil, meaning stronger forces acting on the shot being fired, so those higher pressures will do some added amount of shot deformation (even at pressures within guidelines). Again, not well tested for obvious reasons. Expect extra wad damage, as noted above.
good luck, garrisonjoe

 

Mainly the SAAMI guidelines are concerned with keeping shooters safe when using firearms (and their ammunition). Not what the downrange performance of the load will be.

Generally, higher pressures will open shot patterns, other things being equal. Not many folks want to test patterns from loads that exceed the SAAMI guidelines. Higher pressures also result in more recoil, meaning stronger forces acting on the shot being fired, so those higher pressures will do some added amount of shot deformation (even at pressures within guidelines). Again, not well tested for obvious reasons. Expect extra wad damage, as noted above.
good luck, garrisonjoe

Pressure does not figure in to the recoil equation. It may affect felt/perceived recoil, but actual recoil is a mass/velocity situation.

 

Heres the work sheet for recoil, no pressure figure / number required.
Shotshell Energy

Steve

 

Pressure has nothing to do with it because, in this example, .5 grain more in powder and a different wad develops more pressure but its not faster. There are many more of these examples listed on powder sites, this is just the first one I found.

.

Heres 18 grains

And 18.5 grains

 

How is switching wads a valid comparison?

Show me a pair of loads with the same powder, primer, hull, and wad where adding powder increased velocity without also increasing pressure? What do you think is moving that bullet? And in that comparison, the felt recoil will also change accordingly.

I don't understand the insistence in denying the effect of pressure.

 

Not the same powder drop in grains, but to my point none the less, here is an example of less powder producing more pressure but the same FPS.
Steve

 

Since these tables always go to the nearest 50 fps for velocity, we can assume there is some rounding being done with the velocity numbers. Perhaps one load was actually averaging 1180 fps, and the other 1220 fps.....we'll never know, but to assume there isn't rounding going on would be naïve.

 

If you guys don't realize that as you increase the pressure in a shell by adding more powder, you will also increase the velocity (no other components change), I don't know where to start with a discussion about this. Every load shown in Hodgdon's data which has a range of increasing velocities also has a corresponding increasing pressure (unless someone botched the reading or the typing of the numbers).

good luck, garrisonjoe

 

Pressure might cause velocity, but it does not cause recoil. It's the increase in velocity from 0-1200 fps in a few milliseconds that causes the recoil. Just asks Fig's older brother, Isaac; he'll tell you.

 

Well, Ike would tell you that you don't get velocity without the pressure, so quibble semantically about the word "cause" if you wish, but pressure certainly causes recoil. Without pressure, you have zero recoil, every time.

 

I think that felt recoil coincides with the RATE of acceleration in the payload. I think that quick powders seem to have a sharper recoil than some of the slower powders or at least that's the way it feels to me. All else being equal and that's also ignoring the couple grains of additional slow powder usually needed. The foot pounds generated are the same but the time that it is applied is longer. Like pushing a car. You can push harder for a shorter period of time or easier for a longer time and get the same speed but the net effort is the same. At least that's my understanding of it. The only way to know for sure would be to measure the recoil over time with a transducer. Thanks, Squid Boy

 

I think that felt recoil coincides with the RATE of acceleration in the payload. I think that quick powders seem to have a sharper recoil than some of the slower powders /QUOTE]

We tried that at my club. Nobody could identify from recoil slow powders from fast powders.

Technoid tried the same experiment, perphaps with an check over a chronograph, and got the same results we did.

 

Golden Aways, you are confusing pressure with acceleration. The time factor you are stating is in a 5 milliseconds differential. 100 milliseconds is the minimum time for human nerve response. Pressure is no factor in recoil. If acceleration is measured over plus 100 milliseconds then it is possible one with the fastest nerve response could detect a difference but it would be rare.

 

OK, I didn't mean the same components. What I meant was the same payload at the same muzzle velocity not counting the slight increase in payload from the few extra grains of slow powder that is usually needed. All I am saying is that I can perceive a difference in the way a load FEELS. Feel is a completely personal thing outside the realm of physics and I don't think the way something feels can be measured in any real way. Everybody responds differently to the effect of recoil. I am just saying there is a time factor involved in the application of force and the only way to know is to measure it. Thanks, Squid Boy

 

@Goldens Always
Certainly no where near enough info to tell whether you are comparing apples and apples or apples and oranges. I suspect you realized that and are holding back.
As hint, time matters.

In math and science it only takes one example to disprove a theory, because it has to work every time to be right.
I suggest you find a formula/ equation that we can use to prove your idea. Prove to us, with math, that pressure matters in cases of FPS and recoil. Its time to put up.

Steve

 

@Goldens Always
Certainly no where near enough info to tell whether you are comparing apples and apples or apples and oranges. I suspect you realized that and are holding back.
As hint, time matters.

In math and science it only takes one example to disprove a theory, because it has to work every time to be right.
I suggest you find a formula/ equation that we can use to prove your idea. Prove to us, with math, that pressure matters in cases of FPS and recoil. Its time to put up.

Steve

Man, you don't know much about science. But you haven't come up with a disproof.

 

It has been proven over and over. Equal payload equal speed at muzzle equals the same recoil. The Army conducted extensive tests in the 1940s and again in the late 1950’s and could not show any difference in recoil. They concluded that the most consistent and cost effective powder is the way to go. My small sample test of N100, green dot, 7625, and 4756, 5 experienced trap shooters in a blind test could not pick the difference. Until there is proof and not just opinion I will believe in Dr. Newton.

 

Gold
Tom Armbrust has referred to pressure curve. Having an effect on patterns and felt recoil. I believe that information is what your after.

 

Gold
Tom ambush has referred to pressure curve. Having an effect on patterns and felt recoil. I believe that information is what your after.

Link please?

 

How long before this thread is shut down? We've seen this movie before and know how it ends.

 

And yet you guys fall for the same trap again and again. I need some popcorn!

 

Yeah it is a movie. Fiction at its best. If one tells the story often enough it starts becoming real. Proof is in blind testing not opinion.

 

Someone once said...."if you torture data long enough, it will confess to anything".

 

Back in the 1800s before chokes were invented, live pigeon shooters who had two shots would load less powder [meaning less velocity ] for the second shot. Why ? Because they got tighter patterns. Less pressure meant less initial push on the shot and less set back meaning less shot was deformed at the back of the shot column. More shot stayed round so more shot was in the pattern. I'm sure they didn't try and analyze it like we are, they just knew from experience what worked. Maybe this will explain why we get better patterns with less pressure and velocity, and maybe some of you guys could wake up the dead money shooters from a 150 years ago and argue with them.

 

With all the crazy ways that choke pattern can be achieved... constriction at the end, jug choking, over boring, short taper choke, long taper chokes, and some of the less established things that work like the Pattern Master (which is not exactly constrictions but protruding nubs) that one of the large elements to controlling pattern is....

Controlling the supersonic gasses that leave the muzzle along with the shot.

That's going to take a lot of very high tech computational fluid dynamics to model... or... a bunch of guys building successful shotgun chokes for 125 years.

Given all the details of the original question, mixing up shot velocity and peak pressure is a big mistake.

The question would be "Do low pressure loads (such as with Clays) pattern better than the same velocity load made with Bullseye". One powder being designed for best performance for the purpose, and another classic powder that is very peaky in the pressure curve.

For those very interested, it's almost summer time. Get out the pattern paper and get to reloading.

 

First of all, someone has to define 'low pressure' and 'high pressure'. Good luck.

Not sure who started all this nonsense about pressure affecting patterns but, if this is true then every manufacturer in the world is doing it wrong when it comes to their premium target loads.

......and what about turkey loads, steel loads, bismuth loads, tungsten loads? There is no question, pressure has little to do with pattern performance, regardless of pellet type.

BTW chamber pressure doesn't deform lead pellets, acceleration deforms lead pellets.

Once someone gets off their butt and actually patterns several 'low' pressure loads compared to several 'high' pressure loads, they will see just how wrong they are. If they can even define what low and high pressure mean in a shotshell.

 

BTW, I have tried the above using Universal and 700-X.........I use 700-X in my target loads.

 

There is no way to change pressure without changing something else. You either have to use more or less of the same or powder or a different powder and when you do that you change at least one other variable, likely velocity, in addition to the pressure. It's some other variable that results in the pressure change.

 

Does anyone here honestly think that no one has ever tried this before?

It's a waste of time. And you are going to learn what is already known. Chamber pressure has nothing to do with patterns.

 

What does affect patterns? How round the shot is on muzzle exit. Muzzle region pressure, as it may/can disrupt the shot charge on muzzle exit. Atmospheric conditions and gravity.

All that other crap has little to no affect on patterns.

Use the right powder for the job. Keep acceleration of the load within reason for the gauge and payload weight. Use buffer when it makes sense. Know how much choke you need and how your shotgun performs especially when using larger shot sizes. Pattern, pattern, pattern.

 

Choke affects patterns.

Then shot quality.

Wads, primers, powders, pressures have trivial effect.

Life can be easy if you don't get in the way.

 

The greatest factor influencing patterns may be......patterning.

 

Yup because very few ever take the time to do it correctly.......and then post stuff on this forum that creates confusion.

 

Is this an example of what the argument is about?
This is a quote from Tom Armbrust.
Alliant states it very well in their following news release:

With New American Select Powder, It's Tougher for a Clay Pigeon to get Through Your Pattern.​

"How can your powder affect your pattern? Alliant Powder's ballistics research has demonstrated if it has a fast burn rate and quick pressure rise, it can compress the shot and give you flattened and deformed pellets.. And any shooter knows out-of-round, irregular pellets mean irregular patterns. New American Select is formulated to yield a slower pressure rise and clean burn.. There is a controlled, instead of sudden, compression of the wad, so you get less shot deformation, tighter patterns and more broken birds.

There's another side benefit of American Select's burn rate, too-less felt recoil. It's more like a push than a punch, so at the end of a long day, you'll be ready for those late shoot-offs.

The chemical composition, density, shape and size of American Select are all engineered to produce the "right" burn rate and pressure rise for better patterns and better scores. American Select has been thoroughly tested in combination with a variety of wads, primers and hulls.

American Select is the cleanest-burning powder we've ever made. And it may be the biggest news in smokeless powder since Red Dot was introduced in 1932. When chemists and ballistic researchers get excited about a new powder, it tends to get our attention.

We know there is often resistance to the new and different when it comes to powders and loads, because target shooting is a game of absolute, constant predictability. With some other powder brands we've tested, especially imports, we've found that performance varies from lot to lot and month to month.

With American Select you can count on the same consistency - the same repeatable performance you've come to expect from Alliant's other powders. Properly stored lots of Red Dot powder manufactured in the 1930's will still perform to the same standards they did the day they were produced. And we constantly test the performance of our powders so we can live up to the reputation for consistency we've had for nearly a century.

The powder in your shotshells is not a commodity, it's one of the most important components in target shooting. Better patterns and better scores start with today's powder, new American Select."