Patterning project

[Guest cookoff013]

Guys.

Neutron and at some point will be doing a pattern test. But I really haven't that much experience. Neutron does. I hope he will chime in. I have a few patterning ideas and would like the PW massive to have a banter.

 

One project is to load up a shell from 900fps to 1250fps and pattern to see what happens. But what choke shall we use? ****size? Distance?

 

I intend to put 2 wads head to head in pressure barrel and on pattern plate.

 

I intend to put fibre and plastic head to head, with 2 loadings.

 

I hope to have a concrete plan before stepping one foot on a patterning area and actually have evidence that can be analysed together. Basically make a dataset that is unquestionable within the confines of its parameters.

 

Aka no cooking data.

 

I also wanted to switch out ****sizes in a load from say 1 to 9, in a 1 oz load. Just to see what happens. But I think all loads will revolve around mod choke.

[neutron619]

One project is to load up a shell from 900fps to 1250fps and pattern to see what happens. But what choke shall we use? ****size? Distance?

 

I'm still thinking about all of this (between 17 other non-shooting projects!), but to state a first hypothesis, chokes should be open (e.g. skeet / cylinder) and distances reasonably short (25-30 yards).

 

The reason for this is that it's much easier to see the result of a 5% tightening of a pattern in an overall pattern of 30-40" (i.e. cylinder at 30yd) than it is in a 12" pattern (i.e. full at 25yd).

 

I'll check back later when I've got a bit more time to comment.

[wymberley]

I'll differ and go for the standard 40 yards and middle to diddle choke of 1/2.

 

For reference, the info' obtained in the "First attempt At Patterning" which has been revived (scroll down this sub forum) is extremely comprehensive.

 

One question, are you going to ( I know that you often do) get the MV checked at the Proof House or simply use the calculated charge weight figures?

[Guest cookoff013]

It's fine, take your time. but I wouldn't mind a concrete plan before patterns are shot. I'm sure the tests would take an hour. But thinking a bout the experiment to get the best comparison for everything.

[Guest cookoff013]

I'll differ and go for the standard 40 yards and middle to diddle choke of 1/2.

 

For reference, the info' obtained in the "First attempt At Patterning" which has been revived (scroll down this sub forum) is extremely comprehensive.

 

One question, are you going to ( I know that you often do) get the MV checked at the Proof House or simply use the calculated charge weight figures?

That's a great question. Will proof some

[Stonepark]

Have you considered that if you want to see a true variation in pattern between wads. pressure and speed, you need to use 5% plus antimony shot, otherwise when the pressure exceeds the softer leads limit, the damaged lead will give a wider pattern and skew the results.

[TIGHTCHOKE]

An open choke and work at 30 yds.

 

That way we can hopefully see the variance in speed of load and the different wad types.

 

If upon the initial testing it is found to be too close or too far the distance can be changed but then stick to that chosen distance for all other shots.

[Guest cookoff013]

Would one consider 4% antimony

[TIGHTCHOKE]

Would one consider 4% antimony

 

As against what? Pure lead?

 

The antimony is usually added to lead for the clay shooting market.

[wymberley]

Have you considered that if you want to see a true variation in pattern between wads. pressure and speed, you need to use 5% plus antimony shot, otherwise when the pressure exceeds the softer leads limit, the damaged lead will give a wider pattern and skew the results.

I don't know about these things, but would the velocities in question produce high pressures?

[neutron619]

It's fine, take your time. but I wouldn't mind a concrete plan before patterns are shot. I'm sure the tests would take an hour. But thinking a bout the experiment to get the best comparison for everything.

 

You're an optimist - I like that.

 

At my fastest, in still conditions with everything going to plan, I can shoot 20 patterns per hour with the mobile pattern plate I have. It's frequently less. I think we should be planning for everything you've listed above to take 3-4 days, done properly, and cost about £80 in paper - if you're doing 5 patterns per data point, that is...

[Guest cookoff013]

Double sided pattern paper !

Lol

[neutron619]

I'll differ and go for the standard 40 yards and middle to diddle choke of 1/2.

 

There are lots of reasons to shoot 40-yard patterns. I've even done a handful of particularly capable cartridges at 50 yards, though beyond that it becomes something of a hands-of-the-gods question given the inherent variability of most cartridges at that distance.

 

The main reason not to go out as far as 40 yards is because it's actually quite difficult to shoot exactly the same spot on a pattern plate consistently at that distance, even with a rest.

 

Quite apart from human wobbles, which I'd guess spoil about 1 pattern in 15 (based on an average of about 3 out of 50 or so patterns per roll being off-centre to the point that they have to be thrown away or "adjusted"), shotguns don't always throw the shot to the point of aim, even if your aiming is perfectly consistent. Just a feature of having a wad between the gas and the shot that can be pushed marginally off-axis in this or that direction as it exits the gun, I suppose. That's a lot less of an issue close in.

 

20 yards, just to go the other way for a moment, is too close. It's the same effect as shooting full choke between 25-30 - you get so many pellets in such a tight pattern that it's hard to see any useful difference. Almost everything except the very worst .410 cartridges I've come across will put 90-95% in the circle at 20yd. Most stuff that isn't .410 is 97-99% - at least with my particular set of test guns / chokes. I include evenness, pressure welding, etc. in the former consideration. You also tend to get big fat holes in the paper where the wad goes through, but I rarely see this at 30yd+ - at least with the .410 shells I spend most of my time testing.

 

I've no real problem with half choke at 30yd, though if you want to reduce the variables to the minimum, true cylinder is the one to go for. I posted a few weeks back on another thread about deformation due to pellets impacting the surface of the choke. It's avoidable, provided the barrel walls remain parallel to the direction of travel - i.e. with no choke. Doing that would then mean that any deformation was the result of scrubbing, compression during acceleration, interference with the shot column by combustion gas, or as a result of changing components. Since the last of those is what we're interested in, reducing as far as possible the influence of all the others would seem to be sensible.

 

That's also an argument for the use of the hardest lead available. I'd go so far as suggesting the use of steel or something else super-hard, which would eliminate most of the deformation issues and leave you with only what the effect of the variables under test was. We'd probably need a 12 gauge single barrel from Mick though: I'm not saying it would happen (and motty will be along shortly to tell us that it never has and that it's all made up to scare us ) but we might need to be prepared to destroy a cheap 12 gauge by putting steel shot on top of a nitro card / fibre wad / nitro card stack if we went down that route. Hopefully it would survive long enough to give us some useful data...

Edited October 22, 2017 by neutron619

[wymberley]

That's a great question. Will proof some

Let's assume you do and the work gives a comprehensive result regarding the patterns. However, putting to one side the home loaders, the velocities looked at are not those which are readily available 'over the counter'. If that is considered valid, then how about looking at energy as well as patterns performance-wise?

 

For example, a 900 ft/sec No 6 gives 1 ft/lb at 40 yards as does a 1250 No 7. But which is the better choice for field use? Before someone jumps - the 1 ft/lb is c-ish, but close.

[TIGHTCHOKE]

We could speed things up considerably and adopt the CCPS approach!

[wymberley]

 

There are lots of reasons to shoot 40-yard patterns. I've even done a handful of particularly capable cartridges at 50 yards, though beyond that it becomes something of a hands-of-the-gods question given the inherent variability of most cartridges at that distance.

 

The main reason not to go out as far as 40 yards is because it's actually quite difficult to shoot exactly the same spot on a pattern plate consistently at that distance, even with a rest.

 

Quite apart from human wobbles, which I'd guess spoil about 1 pattern in 15 (based on an average of about 3 out of 50 or so patterns per roll being off-centre to the point that they have to be thrown away or "adjusted"), shotguns don't always throw the shot to the point of aim, even if your aiming is perfectly consistent. Just a feature of having a wad between the gas and the shot that can be pushed marginally off-axis in this or that direction as it exits the gun, I suppose. That's a lot less of an issue close in.

 

20 yards, just to go the other way for a moment, is too close. It's the same effect as shooting full choke between 25-30 - you get so many pellets in such a tight pattern that it's hard to see any useful difference. Almost everything except the very worst .410 cartridges I've come across will put 90-95% in the circle at 20yd. Most stuff that isn't .410 is 97-99% - at least with my particular set of test guns / chokes. I include evenness, pressure welding, etc. in the former consideration. You also tend to get big fat holes in the paper where the wad goes through, but I rarely see this at 30yd+ - at least with the .410 shells I spend most of my time testing.

 

I've no real problem with half choke at 30yd, though if you want to reduce the variables to the minimum, true cylinder is the one to go for. I posted a few weeks back on another thread about deformation due to pellets impacting the surface of the choke. It's avoidable, provided the barrel walls remain parallel to the direction of travel - i.e. with no choke. Doing that would then mean that any deformation was the result of scrubbing, compression during acceleration, interference with the shot column by combustion gas, or as a result of changing components. Since the last of those is what we're interested in, reducing as far as possible the influence of all the others would seem to be sensible.

 

That's also an argument for the use of the hardest lead available. I'd go so far as suggesting the use of steel or something else super-hard, which would eliminate most of the deformation issues and leave you with only what the effect of the variables under test was. We'd probably need a 12 gauge single barrel from Mick though: I'm not saying it would happen (and motty will be along shortly to tell us that it never has and that it's all made up to scare us ) but we might need to be prepared to destroy a cheap 12 gauge by putting steel shot on top of a nitro card / fibre wad / nitro card stack if we went down that route. Hopefully it would survive long enough to give us some useful data...

In effect you're forsaking the advantages for one easily remedied disadvantage. There is one reason why pattern plates measured somewhere in the reason of 6 ft square.

[wigeon jim]

Can't see the point as different guns will produce different results, Jim.

[Stonepark]

Would one consider 4% antimony

 

 

Antimony Percentage Brinell Hardness Max PSI

0 4 5000

0.25 5 5800

1 7 9000

2 8 10250

3 9.1 11600

4 10.1 12900

5 11 14130

6 11.8 15050

 

You would probably get away with 4%, but going from 950fps (and pressures around 5000psi) through to 1250fps (probably around 10500psi), will probably straddle 0 - 3%.

Edited October 22, 2017 by Stonepark

[neutron619]

In effect you're forsaking the advantages for one easily remedied disadvantage. There is one reason why pattern plates measured somewhere in the reason of 6 ft square.

 

Yes, but if I only have a plate of 44" square, you can see my issue?

 

Edit: Furthermore, in lots of cases, a 40-yard pattern is useless. Remember that most of the stuff I test is .410 or at least, small gauge. Lots of cartridges in the small gauges won't throw a consistent 40-yard pattern. You end up with 40-yard sequences going something like 47, 117, 25, 160, 77 which don't really tell you how good the cartridge is - only how lucky or unlucky you've been. That same cartridge at 30 yards might do 110, 102, 94, 106, 100 and look perfectly consistent, but when the pellet velocity drops another 200fps, they all disappear, or not, at random.

Edited October 22, 2017 by neutron619

[neutron619]

Can't see the point as different guns will produce different results, Jim.

 

I seem to remember you've popped up with your "helpful" comments previously. I'm not sure they added much to the discussion last time. This is another, from the same "I'm alright guv" mindset that a lot of folk round here seem to suffer from.

 

Let me spell it out for you:

 

If. We. Keep. The. Gun. The. Same. For. Every. Shot. We. Learn. About. What. The. Different. Cartridges. Do. And. Expound. The. Principles.

 

(N.b. As opposed to the individual use case. This is science - not field testing.)

Edited October 22, 2017 by neutron619

[neutron619]

 

 

Antimony Percentage Brinell Hardness Max PSI

0 4 5000

0.25 5 5800

1 7 9000

2 8 10250

3 9.1 11600

4 10.1 12900

5 11 14130

6 11.8 15050

 

You would probably get away with 4%, but going from 950fps (and pressures around 5000psi) through to 1250fps (probably around 10500psi), will probably straddle 0 - 3%.

 

That does make me think that the steel idea wasn't such a bad one. Gets around all of these issues and would certainly highlight more than anything variations caused by wad, or velocity.

[figgy]

Im looking forward to reading your conclusions to your tests.

 

Would be interesting to see the differences between cylinder bore with different carts your testing and then the exact same cart selection gun and distance with modified half choke. We would then see the correlation of how the the speeds, pressures shot size etc react with choke.

Edited October 23, 2017 by figgy

[Guest cookoff013]

Im looking forward to reading your conclusions to your tests.

Would be interesting to see the differences between cylinder bore with different carts your testing and then the exact same cart selection gun and distance with modified half choke. We would then see the correlation of how the the speeds, pressures shot size etc react with choke.

Unfortunately that is a circular argument there. Because speed will be at the cost of pressure. As we will be adding more powder. It would be good to see what speed the chokes respond to true. Pressure for me has very little to do with pattern, the point is it is so removed from the final result. Pressure being gas measured at 1". We only can correlate speed.

[TIGHTCHOKE]

I think we should get this sorted out and make a start on the patterning, photography and counting/interpretation of the patterns.

[neutron619]

I think we should get this sorted out and make a start on the patterning, photography and counting/interpretation of the patterns.

 

If I knew everyone was so keen, I'd have built another pattern plate. Still waiting on more rolls of paper at the moment though, so it'll be a while yet.