ShotGunWorld Shotguns

It is currently Tue Oct 20, 2020 9:17 pm

All times are UTC - 6 hours [ DST ]


Image



Post new topic Reply to topic  [ 60 posts ]  Go to page Previous  1, 2, 3
Author Message
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Thu Sep 10, 2020 2:56 am 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
bismuth isnt that great, its almost on par with lead. but because its lower density, would mean going silly shot weights and sizes to get an almost comparable shotsize. sure 35 yards is doable.

Tungsten is a different beast altogether when we are actually discussing subsonics. i havent loaded any subs in tungsten, but going on my experience with T12 (1250), it should be very welcome. although i used a silly large shot charge.

if you cost calculate the whole package, between 1,1/2oz bismuth subsonic and say 1oz / 1,1/8oz subsonic tungsten 15-18 in say 7s. they might be comparable. subsonics need normal shotgun powder, not "alan steel powder".
the +30 yard ballistics will be very different. very different. handloading / reloads needednt be troublesome. but must be worth it.

the other thing thats not been discussed is shot travel. shoot tungsten, and it might go beyond a distance thats deemed safe. bismuth shot is comparable as smaller lead shot. but that risk is still there.

cook




Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Thu Sep 10, 2020 12:14 pm 
Crown Grade

Joined: Tue Jun 15, 2004 11:55 am
Posts: 5114
Location: Hemingway, S.C. 29554
I've got some 1 1/8 oz. subsonic bismuth data from Precision Reloading. Send me a PM if you want it. OK, the speed of sound is about 1,123 fps at sea level, depending on temp. etc.. So where are the velocity figures taken & where does it matter? Most reloading data velocities are the 3ft. instrumental velocity. Muzzle velocity is substantially higher, so is it muzzle velocity that matters? Said differently, what are the physical factors that make the sound?
Wildflights,
Thanks for the data. I've got over 20 lbs. of #2 Hevi Shot & the Metro load looks interesting. I can try calling but do you have a guestimate of pressure? BTW, I like Brez much more than some (not calling any names) of the "EXPERTS" that criticize him.
Yea, Cookoff seems to be our leading authority on the subject & has done by far the most research!


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Thu Sep 10, 2020 1:38 pm 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
Its actually me and another guy. Sometimes hes here.
Key is, high pressure, low powder weight, speed 1050fps or less, powder used with payload, larger that normal published data.
Get that right. Thats it


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Thu Sep 10, 2020 2:40 pm 
Crown Grade

Joined: Tue Jun 15, 2004 11:55 am
Posts: 5114
Location: Hemingway, S.C. 29554
I think you misunderstood the question. Is the "SPEED" muzzle velocity? If the 3' instrumental velocity is 1050 fps, the muzzle velocity will be about 100 fps higher & not subsonic! I'm just trying to understand the mechanics. I hope I'm not coming off as a jerk!


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Thu Sep 10, 2020 8:51 pm 
Tournament Grade

Joined: Wed May 16, 2018 7:05 pm
Posts: 150
projectile velocity greater than the speed of sound will be loud on its own. (jet aircraft "sonic boom" is an example of this)

Higher gas pressure at the muzzle will be louder as well.

That is basically the physics of it as I understand it.


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Fri Sep 11, 2020 12:46 am 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
1050 mv at muzzle.
About 930 on chrono 2.5m.

Thats a big guess

Thats numbers from pressure test barrel. Unported cip chamber and barrel.


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Fri Sep 11, 2020 5:37 am 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
TwoFourThree wrote:
projectile velocity greater than the speed of sound will be loud on its own. (jet aircraft "sonic boom" is an example of this)

Higher gas pressure at the muzzle will be louder as well.

That is basically the physics of it as I understand it.


yeah, thats the key to subsonics that are to be used with a moderator. the expelled gas can saturate and exceed the volume of the Moderator and cause a loud report. The uk has fully moderated shotguns / full length shroud. When a friend and i were testing out subsonics for his needs (he has the gun), we had a large amount of recipes to try, the ones that used a powder in the middle or lighter shot charges, caused some loudness and unburned powder in the moderator (sets like concrete, if not cleaned, the powder absorbs moisture.) the best and quiet ones used tiny powder charges 15-17 grains of fast powder. the speeds actually more consistant (through mod gun). this also allowed us to try and work some loads like 12ga 3/4oz lead subsonics for kids, and old people. on phesent days it doesnt mater about range, the birds come to you.
the equilibration of the gas ejected seems to be THE key in keeping things quiet.
when i first shot some, it sounded like a loud fart.

that thread about lead subsonics have alot of relavance comparable to making heavy nontox subsonics (36gram).

the only caveat with all this, practical and theory... there is a limit, once the powder charges get to about 20 grains with whatever, they`ll tend to be loud anyway. thats a large amount of gas, regardless of payload. i did a 42g subsonic 3" in 12gauge fibre wad. didnt think it was quiet-quiet.
still worked, a few guys use them, really big shot for "pest birds"

sorry for long post. but that is where i`m at.


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Fri Sep 11, 2020 9:19 am 
Crown Grade

Joined: Tue Jun 15, 2004 11:55 am
Posts: 5114
Location: Hemingway, S.C. 29554
Thanks for putting up with my dumb questions. I understand the sound barrier thing. That must be why a BP shotgun makes a lot of noise even though the ballistics are often subsonic. It produces a lot of gas! I was shooting squirrels with my SXS ml 11ga. & the next day my neighbor asked me, "what the hell were you shooting?" I guess I will have to do some shooting if I want to know more.


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Fri Sep 11, 2020 12:28 pm 
Tournament Grade

Joined: Mon Jun 16, 2008 3:53 pm
Posts: 285
Location: Hampton, VA
A lot of good information here.

The gas pressure when the wad exits the barrel is key. I think the best way to lower it to the minimum amount is to use a fast powder to get the payload up to target speed of say 1000fps with good shell pressure (you still need pressure for consistent, reliable powder burn). Burn up all the powder in the first few inches of barrel and then let that pressure behind the wad decrease as the wad travels down the barrel (ideal gas law once all powder is burnt and converted to gas/combustion products).


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Fri Sep 11, 2020 1:56 pm 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
Undrcoverrednek wrote:
A lot of good information here.

The gas pressure when the wad exits the barrel is key. I think the best way to lower it to the minimum amount is to use a fast powder to get the payload up to target speed of say 1000fps with good shell pressure (you still need pressure for consistent, reliable powder burn). Burn up all the powder in the first few inches of barrel and then let that pressure behind the wad decrease as the wad travels down the barrel (ideal gas law once all powder is burnt and converted to gas/combustion products).

The powder is all burned up in the first inch in the chamber. The pressure detection device on test barrels is 25/30mm in the chamber.
Gas pushes shot, not powder, or burning anything. Gas does.


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Sat Sep 12, 2020 1:52 am 
Crown Grade
User avatar

Joined: Thu Oct 30, 2008 12:47 am
Posts: 12756
Location: Covington, WA USA
Undrcoverrednek wrote:
A lot of good information here.

Boy, no kidding huh?

Cook, - this is a real nice piece of work, thanks for posting it all here !


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Sat Sep 12, 2020 2:41 am 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
There are no dumb questions. I spent alot of years reading up and actually testing. What these subs really helped me is, powder only has a set amount of energy to give. Set amount per grain. More powder = more energy. The larger payloads always seems to just take a little more energy from the powder, than normal medium payloads for that powder. With subs there is an energy limit for each payload weight. I calculated that for a powder i was using, loaded it up. And had it tested. Bang on the money. Fps spot on.
I cant guess pressures. Thats something i cant do.

What i can do, is get "reputable" data, break it down to ftlbs, ftlbs per grain of powder, through.....


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Sat Sep 12, 2020 3:15 am 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
cookoff013 wrote:
There are no dumb questions. I spent alot of years reading up and actually testing. What these subs really helped me is, powder only has a set amount of energy to give. Set amount per grain. More powder = more energy. The larger payloads always seems to just take a little more energy from the powder, than normal medium payloads for that powder. With subs there is an energy limit for each payload weight. I calculated that for a powder i was using, loaded it up. And had it tested. Bang on the money. Fps spot on.
I cant guess pressures. Thats something i cant do.

What i can do, is get "reputable" data, break it down to ftlbs, ftlbs per grain of powder, through.....


..... through a series of loads, load ladders are fantastic at this. i can then make a reverse assasment for a powder load and calculate the grains to get whatever speed for larger payloads. i cant guess pressures. thats why i test. i also get data for a powder through the different gauges. meaning i have a 12gauge powder that is used for 20 gauge loads. calculate both energies per grain of every load. then i can make an assessment as to what the max energy i can get from that powder. the smaller gauges are always more efficient, it doesnt always pan out, but it gets close to guessing speed.

with this knowlege, i can spot some lemons from a mile away. but i cant compare dataset 1 vs dataset 2 completely because they are more than likley done on non compatable measuring machines.

more datasets mean more accurate guess. this is what i`ve been doing for a while. with that concept i can apply a formula to a load and fps i want, load up nearly anything and there is a good chance it would be close. one load i did, was from slightly suspect data and i was 1/26th out on a powder charge, it was still good.


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Tue Sep 15, 2020 4:52 am 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
Ok,

i want to make a make believe fantasy "lead" subsonic shell.

lets do some maths. what i`m going to do is "theoretical" but evidently needs to be tested in a pressure barrel.
ok, this is theoretical. (i`m just saying again).

lets take a powder theoretical called "BRITISH DOT" its just a make believe powder.

1, look at data. find data where the powder is being used at is largest payload.

i select the hull i will be using. i like chedder hulls.
i get data for all the loads that use the powder / hull at its highest shot charge, middle shot charge and lowest shot charge.
i need speed / payload data. for this mystery "make believe" powder

do not use compression wad / non compression wad data interchangably.

2, i tabulate the data
calculate the ftlbs, and ftlbs per grain of powder for every load.

like so..

21gn - 1300fps - 1oz - 1621 total ftlb - 77.1 ftlb per grain of powder
19.5 - 1200fps - 1,1/8oz - 1579 total ftlb - 80.9 ftlb per grain of powder

look the heavyer payload takes more energy from the powder. This is really important. even though it has less powder
it takes more energy from the smaller powder charge. Lets abuse this.

3, calculate the subsonic we want - 1,1/4 oz. no powder data available because the shot weight too heavy.

subsonic 1050fps 1,1/4oz needs 1359 ftlbs of energy. i calculated it. Using the highest energy extraction would
give us a theoretical powdercharge, at that efficiency.

1359ftlb / 80.9 (max energy extraction from above) = 16.9 grains of powder potentially.

WRONG ! that powder charge is too hot, its at the wrong efficiency.

because the even larger shotweight will extract even more energy per grain, than the upper energy extraction!
Pressures woulds be exponential. unfortunately these calculations are linear.

so taking a wild stab in the dark, the energy efficinet increase is a factor of .. 0.953. thats (77.1 / 80.9)
the powder is about maybe 5% more efficient? going from 1oz to 1,1/8oz. going even higher in shotweight is going
to be way more efficient. going on a pure guess my potential powder charge 16.9grain * 0.953 = 16.1grain of powder.
thats about near the right powder charge.

thats going on the efficiency jumping from 1oz to 1,1/8oz. i can just use another calculation of 0.9 instead of .953
which is 15.2 grain. (thats about the start i`d want.). or i could calculate 0.953 of this re-adjusted powdercharge.
works out to 15.1 grain.

i would load up some shells, and send them off for testing.
powder charges of 15grain 15.5grain 16grain.
i would make them with the tallest compression section, and or maybe roll turn the finish.

i cannont guess pressures. thats what pressure barrels are for !

also i cant use a non compression nontox wad with this data, and i cant use the powder data to model a 1,1/2 oz subsonic.


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Tue Sep 15, 2020 6:52 am 
Presentation Grade
User avatar

Joined: Tue Feb 27, 2018 12:32 pm
Posts: 555
Thanks Cookoff. Informative and interesting.


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Tue Sep 15, 2020 7:42 am 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
Hal4son wrote:
Thanks Cookoff. Informative and interesting.

Cool. Hope it makes sense? Its just calculating how to guess.
The only thing i can say, if your donor data is crap, the latter calculations are crap.

The .953 *.953 is just a straight guess to try and make a number to guess the efficiency of the upper payload jump. So 95% of 95% etc.
But thats just guessing.

The other point is, powder has a set amount of energy it wont give out any more than it has. What that plateau is, i do not know. No calculations can deal with that


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Tue Sep 15, 2020 7:45 am 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
Also you can do an energy break down with the highest payload, and recalculate how much powder gets you 1050 fps.

That might not be clean,


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Tue Sep 15, 2020 10:50 am 
Tournament Grade

Joined: Mon Jun 16, 2008 3:53 pm
Posts: 285
Location: Hampton, VA
Cookoff, thanks for continuing to share your methods. Can you confirm the formula used to calculate the energy? I am using (payload weight in grains) x (velocity in fps ^2) / 450240. My numbers are close to yours, but not exact.

I've found out the neighbors aren't moving in until jist after our season finishes so I have a whole year to experiment.


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Tue Sep 15, 2020 11:24 am 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
Yeah,
My numbers are really loose.
Really loose. I didnt care too much about accuracy. Just meth


Top
 Profile  
 
 Post subject: Re: Subsonic Waterfowl Load Questions
PostPosted: Tue Sep 15, 2020 11:26 am 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3683
Location: UK, England, Britain
Method*




Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 60 posts ]  Go to page Previous  1, 2, 3

All times are UTC - 6 hours [ DST ]


Who is online

Registered users: 391TODT11, albanygun, Auldthymer, bigeejakes, Bing [Bot], birdhunter39, Bladeswitcher, Cajunboy7, casonet, ch47intrim, chemclay, cole1, CuriousGeorge*, Curly N, Deputydad, doppelflinten, doug_andrea, Eric87000, EricB, euphos, Google [Bot], Google Adsense [Bot], Google Feedfetcher, Hal4son, hopper810, Jaspo01, Joe Hunter, Joeracer44, John H, Johnnyhonda440, jwbducks, Koslamp, mactownbob, Majestic-12 [Bot], Mark Pfeifer, Matalpa2, May, Nebs, ohio mike, Old No7, oneounceload, osok1, Pettifogger1, Pirates55, rans, rbaldwin, rkumetz, Rockett0, Rooster booster, saskbooknut, Shed, slotracer577, StevenZ, thecoinopcollector, Tidefanatic, Tireddad, Undrcoverrednek, ushoot2, VetEyeDoc, Virginian, Win50, xsshooter


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group    - DMCA Notice