Author Topic: Short barrel, tight choke and 00 buckshot (Read 5702 times)

RMc · « **on:** December 15, 2021, 11:49:27 pm »

A few days ago I decided to check out some, pre-pandemic, 3" Federal Premium 15 pellet 00B loads in the "franken gun" I put together some years back. This is a Mossberg Maverick that I set up with a model 500 18.5" heavy contour barrel that came set up for accu-choke tubes. The barrel was billed as a contract overrun for an LE agency - plain barrel with a brass bead sight. The original Maverick plastic stock was too long so a 70s era bargain-bin Mosberg wood stock was installed. Shorter with a little more drop at comb and heel. Certainly more convenient in and out of the 4x4. The ribbed black plastic forend stayed while sling swivels and and quick detach "mountain sling finished out the "franken."

The choke tube used was a XF Comp-N-Choke, (billed as having a .690" exit diameter). Some would say that is too tight for 00B! Anyway, late to the range, so I limited my patterning to 25 yards, 4 rounds at 4 targets.

Cut to the chase. All four patterns had 12 pellets in the 10 inch pattern core and with the exception of one flier, the remaining pellets hit within 15 inches from pattern center.

Not bad.

WeTheArmed.com

GeorgeHill · « **Reply #1 on:** December 16, 2021, 07:55:38 am »

Playing around with different choke could give you some bet results. But might not be worth it... That good very good for a hunting load.

RMc · « **Reply #2 on:** December 17, 2021, 06:44:49 pm »

George, it is good to see you posting here again!

After your reply, I decided to examine the factory loads in question a little closer. I cut off the crimp from two of the 15 pellet 00B loads and held the pellet stack in place while pouring out the buffer. The pellet stack was two pellets per layer with a lone single pellet on top. The thick plastic shotcup held ten pellets with less than half of last two extending above the shot cup. The 11th and 12th pellets were just barely within the stack influence of the shot cup.

Things really changed with the remaining three 00B pellets. These pellets still followed the stack pattern, but due to the extra hull space, rested primarily on the pellet immediately below. Meaning the pellets could roll side to side depending on shell angle. I suspect this may be factor contributing to pattern trend shown.

The use of a patterning standard of a 10" core and 5" outer ring is my shorthand way of judging conventional buckshot patterns. And consider any pellet strike outside of the 15" total to be lost to the pattern as a practical matter.

coelacanth · « **Reply #3 on:** December 18, 2021, 01:50:59 pm »

Good info on those Federal shells. Thanks.

Roper1911 · « **Reply #4 on:** December 19, 2021, 12:00:02 pm »

Quote from: RMc on December 17, 2021, 06:44:49 pm

George, it is good to see you posting here again!

After your reply, I decided to examine the factory loads in question a little closer. I cut off the crimp from two of the 15 pellet 00B loads and held the pellet stack in place while pouring out the buffer. The pellet stack was two pellets per layer with a lone single pellet on top. The thick plastic shotcup held ten pellets with less than half of last two extending above the shot cup. The 11th and 12th pellets were just barely within the stack influence of the shot cup.

Things really changed with the remaining three 00B pellets. These pellets still followed the stack pattern, but due to the extra hull space, rested primarily on the pellet immediately below. Meaning the pellets could roll side to side depending on shell angle. I suspect this may be factor contributing to pattern trend shown.

The use of a patterning standard of a 10" core and 5" outer ring is my shorthand way of judging conventional buckshot patterns. And consider any pellet strike outside of the 15" total to be lost to the pattern as a practical matter.

That top one is the flyer.
2x2 stacks of 00 pattern *MUCH* better then traditional 3x3. so 8, 10, 12, and 14.

RMc · « **Reply #5 on:** December 19, 2021, 04:38:44 pm »

Quote from: Roper1911 on December 19, 2021, 12:00:02 pm

That top one is the flyer.
2x2 stacks of 00 pattern *MUCH* better then traditional 3x3. so 8, 10, 12, and 14.

I agree. And I now informally dub this phenomena as:

Lone Pellet Flyer Syndrome

RMc · « **Reply #6 on:** January 02, 2022, 01:38:37 am »

Bit of follow through.

When I decided to try the "Franken" for field use, I looked through my relatively minimal selection of Accu-Choke / Invector / Winchoke tubes. After discovering the long forgotten XF Comp-N-Choke, I checked the company website and found the XF constriction was recommended for 000 & 00 Buckshot.

Since my first patterning session, I found a few boxes of three inch Federal Premium 000B. These long stored shells dated back several years before the current pandemic induced supply disruption. Dissecting one of the rounds found 10 buckshot stacked in two pellet layers. Eight contained within a short shotcup and two pellets completely above the shotcup. Like the 00B rounds tested earlier, these also contained a coarse ground plastic buffer.

Only two patterns were fired at the 25 yard pattern paper, before a thunderstorm interupted the proceedings. The first round kept 8 pellets barely within the 10 inch core and two just inside the 5 inch annular ring. The second placed 8 pellets well centered within the 10 inch core. Of the remaining pellets one hit the outer edge of the annular ring and the other struck 13 inches from the pattern center.

Admittedly looking for trends in just two patterns is something of a stretch. These did seem to indicate a markedly wider spread for those pellets not contained within the shotcup. As did the three inch 00B rounds previously tested. At least, that is, with this shotgun / choke combination.

Roper1911 · « **Reply #7 on:** January 03, 2022, 09:49:41 pm »

Quote from: RMc on January 02, 2022, 01:38:37 am

Bit of follow through.

When I decided to try the "Franken" for field use, I looked through my relatively minimal selection of Accu-Choke / Invector / Winchoke tubes. After discovering the long forgotten XF Comp-N-Choke, I checked the company website and found the XF constriction was recommended for 000 & 00 Buckshot.

Since my first patterning session, I found a few boxes of three inch Federal Premium 000B. These long stored shells dated back several years before the current pandemic induced supply disruption. Dissecting one of the rounds found 10 buckshot stacked in two pellet layers. Eight contained within a short shotcup and two pellets completely above the shotcup. Like the 00B rounds tested earlier, these also contained a coarse ground plastic buffer.

Only two patterns were fired at the 25 yard pattern paper, before a thunderstorm interupted the proceedings. The first round kept 8 pellets barely within the 10 inch core and two just inside the 5 inch annular ring. The second placed 8 pellets well centered within the 10 inch core. Of the remaining pellets one hit the outer edge of the annular ring and the other struck 13 inches from the pattern center.

Admittedly looking for trends in just two patterns is something of a stretch. These did seem to indicate a markedly wider spread for those pellets not contained within the shotcup. As did the three inch 00B rounds previously tested. At least, that is, with this shotgun / choke combination.

I've doubled down on my shotgun obsession, and yeah. all the pellets need to be in the shotcup. if you pulled the wads and swapped them for taller ones you'd see a big improvement I'd bet.
THAT SAID-
10-13 inches at 25 yards is excellent patterning. I think only Vang and flitecontrol could do better.

RMc · « **Reply #8 on:** January 07, 2022, 09:26:47 am »

Quote from: Roper1911 on January 03, 2022, 09:49:41 pm

I've doubled down on my shotgun obsession, and yeah. all the pellets need to be in the shotcup. if you pulled the wads and swapped them for taller ones you'd see a big improvement I'd bet.
THAT SAID-
10-13 inches at 25 yards is excellent patterning. I think only Vang and flitecontrol could do better.

Yes, a full length shot cup would make a difference in these Federal Premium buckshot loads. Across the 3" magnum load patterns fired here, the core patterns, (all within 10"), had the same number of pellets that were contained within the short factory shot cup.

coelacanth · « **Reply #9 on:** January 07, 2022, 03:55:06 pm »

Have either of you experienced a situation where the pellet spread is not linear over increased range increments? The reason I ask is my coach gun ( Savage/Stevens 311 ) with both barrels shortened to 18.5" does not pattern the same from both barrels. I assume I have removed the choked barrel section(s) at this point and both are now essentially cylinder bore. The barrels were cylinder bore on the right and improved cylinder on the left. The left barrel will usually pattern with the right out to about fifteen yards but from there out to thirty yards the right barrel continues to spread the shot pattern and the left stays about the same size or only slightly larger than it was at fifteen out to twenty five or so and then they are about the same again by thirty to thirty five yards. Weird.

I thought it might be inconsistency from the ammo ( mostly Winchester commercial, brown box law enforcement stuff - brown box, 2.75", high brass, red hulls and 9 pellets ) but it happens frequently enough to remove random chance form the equation. I have had similar results from some Fiocchi ammo as well. I considered that I might have some beginnings of choke left in that barrel but they mic the same inside diameter.

Roper1911 · « **Reply #10 on:** January 07, 2022, 09:35:49 pm »

Quote from: RMc on January 07, 2022, 09:26:47 am

Yes, a full length shot cup would make a difference in these Federal Premium buckshot loads. Across the 3" magnum load patterns fired here, the core patterns, (all within 10"), had the same number of pellets that were contained within the short factory shot cup.

Yeah. I'm looking at using 1 1/8th to 1 1/4th ounce wads for my buckshot loads. Probably a figure 8 or WAA12.

Quote from: coelacanth on January 07, 2022, 03:55:06 pm

Have either of you experienced a situation where the pellet spread is not linear over increased range increments? <\snip>

Shotguns are fickle beasts. But yeah. Once a shell goes subsonic the spread does... Weird things. The shot pattern is often said to be a cone widening 1 inch per yard, but it's more a trumpet bell. The first few yards it hardly spreads. Then once it leaves the wad it starts spreading a little, then in maintains rate of spread by mm per microsecond as it slows down. So if it widens 10mm a microsecond it'll keep that approximate rate. But as it slows down it's forward momentum that force spreads them further apart in per foot covered towards the target.
Having said all that: we're talking extreme ranges. For this to be noticable you really have to be slinging lead out to like- 300 yards. At actual use ranges it's a non issue.
Yes I got looked at odd shooting a shotgun at 200 yards with buck.
The science demanded it though.

Plebian · « **Reply #11 on:** January 09, 2022, 02:36:59 pm »

Quote from: Roper1911 on January 07, 2022, 09:35:49 pm

Yeah. I'm looking at using 1 1/8th to 1 1/4th ounce wads for my buckshot loads. Probably a figure 8 or WAA12.
Shotguns are fickle beasts. But yeah. Once a shell goes subsonic the spread does... Weird things. The shot pattern is often said to be a cone widening 1 inch per yard, but it's more a trumpet bell. The first few yards it hardly spreads. Then once it leaves the wad it starts spreading a little, then in maintains rate of spread by mm per microsecond as it slows down. So if it widens 10mm a microsecond it'll keep that approximate rate. But as it slows down it's forward momentum that force spreads them further apart in per foot covered towards the target.
Having said all that: we're talking extreme ranges. For this to be noticable you really have to be slinging lead out to like- 300 yards. At actual use ranges it's a non issue.
Yes I got looked at odd shooting a shotgun at 200 yards with buck.
The science demanded it though.

I am sure some of the pellets are likely interfering with other pellets aerodynamically when close enough together right after the wad separation to throw some more randomness into the equation as well. There is a large amount of effects all coming together at once in shotgun projectiles in flight.

It is well past my pay grade to even attempt to understand the math going on what seems to be a pretty simple process, at first glance.

Roper1911 · « **Reply #12 on:** January 09, 2022, 05:21:04 pm »

Quote from: Plebian on January 09, 2022, 02:36:59 pm

I am sure some of the pellets are likely interfering with other pellets aerodynamically when close enough together right after the wad separation to throw some more randomness into the equation as well. There is a large amount of effects all coming together at once in shotgun projectiles in flight.

It is well past my pay grade to even attempt to understand the math going on what seems to be a pretty simple process, at first glance.

I've only seen detailed shots of close 00 buck shockwaves, but the turbulence caused by a single pellet isn't that much. At least when compared to the wad. Does it affect them? Yes. But trying to account for it is really difficult and makes about as much difference as accounting for Coriolis effect on 100 yard shot, once the pellets have separated by even a few inches, they functionally have no effect on each other. It puts a little bit of randomness in the first 5 to 15 yards, but other that I can't imagine it making much difference.

RMc · « **Reply #13 on:** January 11, 2022, 12:31:03 am »

Subsonic:

At 45 degrees Fahrenheit, the speed of sound runs 1100 fps.

Federal Premium three inch 12 ga, 15 pellet 00B is rated at 1210 fps.
At 45 deg. F. these would go subsonic at approximately 12 to 13 yards.

Roper1911 · « **Reply #14 on:** January 11, 2022, 09:17:51 pm »

Quote from: RMc on January 11, 2022, 12:31:03 am

Subsonic:

At 45 degrees Fahrenheit, the speed of sound runs 1100 fps.

Federal Premium three inch 12 ga, 15 pellet 00B is rated at 1210 fps.
At 45 deg. F. these would go subsonic at approximately 12 to 13 yards.

buckshot goes subsonic at approximately 25-30 yards for most defensive ammo. HV 00 buck can reach 60-80 yards.
a pellet of 00 buck has a profile of 1, so it's BC and SD are the same. which is a horrific 0.070.

RMc · « **Reply #15 on:** January 12, 2022, 02:45:00 am »

Update: Source information included.

Subsonic:

At 45 degrees Fahrenheit, the speed of sound runs 1100 fps.

See: https://www.weather.gov/epz/wxcalc_speedofsound

Federal Premium three inch 12 ga, 15 pellet 00B is rated at 1210 fps.
At 45 deg. F. these would go subsonic at approximately 12 to 13 yards.

See http://www.ctmuzzleloaders.com/ctml_experiments/rbballistics/web_apps/rb_ballistics.html

This is for lead ball weights. Use .33" for nominal 00B. Enter velocity, ball diameter and air temp.

Roper1911 · « **Reply #16 on:** January 12, 2022, 06:16:24 am »

Quote from: RMc on January 12, 2022, 02:45:00 am

Update: Source information included.

Subsonic:

At 45 degrees Fahrenheit, the speed of sound runs 1100 fps.

See: https://www.weather.gov/epz/wxcalc_speedofsound

Federal Premium three inch 12 ga, 15 pellet 00B is rated at 1210 fps.
At 45 deg. F. these would go subsonic at approximately 12 to 13 yards.

See http://www.ctmuzzleloaders.com/ctml_experiments/rbballistics/web_apps/rb_ballistics.html

This is for lead ball weights. Use .33" for nominal 00B. Enter velocity, ball diameter and air temp.

our ballistic calculators grievously disagree. I wonder which one is right. my research leads me to believe the BC is 0.070. he's using something much worse.
I think mine is probably "Ideal" and his is probably "worst case"

Roper1911 · « **Reply #17 on:** January 12, 2022, 11:20:59 pm »

this bugged me, so I spent like- three hours on it and figured out how to calculate BC by hand. which gave me a BC of 0.045, subsonic at 18 yards.
you get the transonic "jump" observed in precision rifles in the 1130-1070 range. it does effect shotgun pellets, but the extra scatter isn't observable at close range. it's honestly academic because who the hell shoots buckshot past 100 yards, and it's super hard to quantify because shotguns are also super random.
TLDR I'm a nerd about this stuff, and the "strange ballistics" you can observe occur so far outside the engagement range of buckshot they don't matter.

GeorgeHill · « **Reply #18 on:** January 14, 2022, 01:36:33 am »

Wow. Forgive me my rather incoherent post.

The Aerodynamic effect on pellets...
After a few inches of separation they no longer effect each other... That's true. That's true. But the effect was enough to put the pellets into different trajectories, hence the continued cone of dispersion. It would be very lovely if a payload of shot only ever spread to the size of a dinner plate regardless of range. That would be awesome.

Roper1911 · « **Reply #19 on:** January 14, 2022, 09:04:03 am »

Quote from: GeorgeHill on January 14, 2022, 01:36:33 am

Wow. Forgive me my rather incoherent post.

The Aerodynamic effect on pellets...
After a few inches of separation they no longer effect each other... That's true. That's true. But the effect was enough to put the pellets into different trajectories, hence the continued cone of dispersion. It would be very lovely if a payload of shot only ever spread to the size of a dinner plate regardless of range. That would be awesome.

Yes. Though the spread is probably more due to the very slight angle each pellet has leaving the barrel, that's why Vang/long forcing cones/chokes work. They change the angles at which the pellet leave the barrel, assuming the internal ballistics of a shotgun operate in the method I assume.
I really, really want a high speed camera so I can study this in depth.

Roper1911 · « **Reply #20 on:** February 26, 2022, 10:19:57 am »

because I have what people call "a problem" I've decided to tap the SBS I'm working on for chokes.
I'll keep you updated.

Also- I learned recently that the "trumpet" shot pattern is more obvious on steel shot because it deforms less, and bounces more. i learned this while reading up on shot buffer.

Roper1911 · « **Reply #21 on:** August 12, 2022, 10:34:30 am »

Quote from: GeorgeHill on January 14, 2022, 01:36:33 am

Wow. Forgive me my rather incoherent post.

The Aerodynamic effect on pellets...
After a few inches of separation they no longer effect each other... That's true. That's true. But the effect was enough to put the pellets into different trajectories, hence the continued cone of dispersion. It would be very lovely if a payload of shot only ever spread to the size of a dinner plate regardless of range. That would be awesome.

I recently got to spend some time with people whose knowledge of the combat conduit makes mine seem small.
And they handed me my ass on this, firmly reminding me that while I know more then most people do about God's gift of the battle pipe, I'm still a student.
I finally got to see highspeed Schlieren imaging of shot patterns in flight, the aerodynamic interactions are honestly beyond description. First: I was wrong. Not totally, but I understated the effects of the shock cones and other exterior aerodynamics. It's really too complicated to describe in text without writing a whole scientific paper on it. The bare functional basics are hard for me to grasp, there is so much going on in those first effective 40 yards.

coelacanth · « **Reply #22 on:** August 27, 2022, 12:46:56 am »

Agreed. The number of variables is staggering.