ShotGunWorld Shotguns

It is currently Sat Oct 24, 2020 4:05 am

All times are UTC - 6 hours [ DST ]


Image



Post new topic Reply to topic  [ 17 posts ] 
Author Message
 Post subject: Velocity Change Per Powder Change Increment
PostPosted: Sun Oct 11, 2020 8:13 am 
Field Grade

Joined: Sun Mar 21, 2010 2:05 pm
Posts: 32
I was looking at a load on Alliant Powder for 2-3/4" with Fed GM hulls.

W209 primer, 24 grains Unique powder, 12S4 wad and 1-1/4 oz lead.

It is listed 1225 fps @ 9500 psi.

Is there a rule of thumb or does anyone have an educated guess how velocity will respond versus a given powder increase?

I want to get the velocity up to my standard load at 1250. I know 25 fps doesn't seem appreciable but when you are old and shoot bad like I do, anything to stack the deck helps.

I know I can get there experimenting with a few shells and my chrony but it's 25 mile drive and it's raining for days now, a starting point would be nice!

It looks like there is a little bit of wiggle room at 9500 psi especially considering I am shooting them in a 3-1/2" chambered gun.




Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Sun Oct 11, 2020 8:48 am 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3688
Location: UK, England, Britain
Is that the max powder charge posted by alliant?
There might not be wiggle room for that load.

Just use as is or buy different powder


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Sun Oct 11, 2020 8:56 am 
*Proud to be a*
*Proud to be a*

Joined: Sun Nov 09, 2003 6:01 pm
Posts: 6740
I would not go over the maximum loading for a load.

I have plotted the published data for several loads for the powders I use and within the range of loads listed in the manual the powder/velocity relationship is linear. So the math for what you want would be easy. I did not plot pressures since I was woriking under the max listed.

But...there is no reasonable expectation that the powder/pressure relationship is linear above the max load. You are flying blind in what is considered prohibited airspace.


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Sun Oct 11, 2020 9:09 am 
*Proud to be a*
*Proud to be a*
User avatar

Joined: Thu Mar 05, 2009 10:56 pm
Posts: 7442
Location: Central ND
duurmeehr,

You can figure between 35 to 50 FPS for each grain of powder.......but that is only a w.a.g.

Just remember for each powder increase there will also be a pressure increase. So increasing powder is something you need to think about. The more chamber pressure you start with the higher the chamber pressure increases as you add powder. As an example at 8,300 PSI when you add a grain of powder the chamber pressure may increase to 9,000 PSI. At a chamber pressure of 9,000 PSI adding that grain of powder may increase the pressure to 10,200 PSI and so on. Velocity may increase in many instances in a fairly linear direction per grain of powder, chamber pressure does not.

The worst part about this whole deal of increasing powder/velocity............. increasing velocity will not help with your ability to hit a target clay or live bird.

Just being honest, no intention of being offensive.

_________________
Mark

aka Mr. Tactful. Common sense no longer appears to be common.
NSCA#544066


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Sun Oct 11, 2020 9:18 am 
Crown Grade
User avatar

Joined: Tue Jan 08, 2008 6:20 pm
Posts: 22552
Reloading will give you ~ that much difference in your speeds anyway.

_________________
The bitterness of poor quality is remembered long after the sweetness of low price has faded from memory, Aldo Gucci

Never argue with an idiot. They will only bring you down to their level and beat you with experience, George Carlin


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Sun Oct 11, 2020 9:41 am 
Field Grade

Joined: Sun Mar 21, 2010 2:05 pm
Posts: 32
All well taken.

Alliant doesn't show where it is in the pressure range. They only list one loading.

I need to get some loading books out like Lyman and see what they show.

Thanks for the advice!


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Sun Oct 11, 2020 9:52 am 
Field Grade

Joined: Sun Mar 21, 2010 2:05 pm
Posts: 32
Lyman's says you can go to 25 grains with a CCI 209 @1300 with the 12S4 wad and still be good on pressure.

I need to chrony that actual load from Alliant and see what it is really doing.

It may be real close already.

Thanks again.


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Sun Oct 11, 2020 12:52 pm 
Crown Grade

Joined: Thu Aug 31, 2006 10:06 am
Posts: 3688
Location: UK, England, Britain
Your loads might be faster!


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Sun Oct 11, 2020 1:11 pm 
Field Grade

Joined: Sun Mar 21, 2010 2:05 pm
Posts: 32
cookoff013 wrote:
Your loads might be faster!


That is exactly what I was thinking after the fact.

I have seen it go both ways, sometimes faster than listed sometimes slower.

A lot depends on powder lots as well I am thinking.


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Sun Oct 11, 2020 1:38 pm 
Moderator
Moderator
User avatar

Joined: Fri Nov 04, 2005 11:15 am
Posts: 23003
Location: Knoxville, Tn area Nyuck, Nyuck
Your ammo is probably closer to what the load data say regardless of what your standard chronograph indicates. There are built in errors in your optic chrono.

_________________
Take a few minutes and watch this, https://youtu.be/TmfeNq5x5aQ

Let us endeavor so to live so that when we come to die even the undertaker will be sorry.
Mark Twain


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Mon Oct 12, 2020 5:25 am 
Crown Grade

Joined: Sat Feb 05, 2005 4:51 pm
Posts: 10875
Location: Phoenixville PA
You are only changing the lead on a target by about an inch or so at 25 to 30 yards with that slight increase of velocity you want. It will NOT improve your shooting!

_________________
BobK


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Mon Oct 12, 2020 7:35 am 
Limited Edition

Joined: Sat Mar 27, 2010 4:16 pm
Posts: 359
Location: Escanaba, MI
^ what BobK said.

I had a friend get into reloading recently and wanted to load some super fast stuff "so he could decrease his leads." So I did the math...

Target at 30yds, true 90 degree crosser at 45mph (I think that's skeet target speed, so basically a station 4 but 9 yards farther). Changing velo from 1200fps to 1450 decreased the necessary lead by 10.3 inches, from 4.95ft to 4.09ft.

If that target is an outgoer at 45 degrees shot at 30yds it decreased from 3.5 to 2.9ft or 7.2"
Extrapolate that to a 25fps change and that math is easy, 1/10 of my calculations. Again, BobK right on.

My math did not deter him. And of course he loaded them with 9/8oz. The good news is, shot out of my versamax they're tolerable so he gave me 3 or 4 boxes for crows :)


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Tue Oct 13, 2020 9:00 am 
Crown Grade

Joined: Sun Mar 03, 2013 11:01 am
Posts: 6069
Location: Newton Kansas
DooFighter wrote:
^ what BobK said.

I had a friend get into reloading recently and wanted to load some super fast stuff "so he could decrease his leads." So I did the math...

Target at 30yds, true 90 degree crosser at 45mph (I think that's skeet target speed, so basically a station 4 but 9 yards farther). Changing velo from 1200fps to 1450 decreased the necessary lead by 10.3 inches, from 4.95ft to 4.09ft.

If that target is an outgoer at 45 degrees shot at 30yds it decreased from 3.5 to 2.9ft or 7.2"
Extrapolate that to a 25fps change and that math is easy, 1/10 of my calculations. Again, BobK right on.

My math did not deter him. And of course he loaded them with 9/8oz. The good news is, shot out of my versamax they're tolerable so he gave me 3 or 4 boxes for crows :)

For me, hunting Turtledoves, that was enough to reduce my missing aft by over half.
Thus the reason my Dove Load is 7/8oz of 9's @ 1400+ (don't recall specifically).
Prior I got a LOT of tail feathers instead of birds.

_________________
I don't always venture out into the sub-freezing darkness, but when I do, it is hunting season, and I carry a Browning. Stay hungry my friends.


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Tue Oct 13, 2020 6:06 pm 
Crown Grade

Joined: Sun May 17, 2015 6:25 pm
Posts: 2672
Location: On the wrong side of the river, Austin TX
DooFighter wrote:
^ what BobK said.

I had a friend get into reloading recently and wanted to load some super fast stuff "so he could decrease his leads." So I did the math...

Target at 30yds, true 90 degree crosser at 45mph (I think that's skeet target speed, so basically a station 4 but 9 yards farther). Changing velo from 1200fps to 1450 decreased the necessary lead by 10.3 inches, from 4.95ft to 4.09ft.

If that target is an outgoer at 45 degrees shot at 30yds it decreased from 3.5 to 2.9ft or 7.2"
Extrapolate that to a 25fps change and that math is easy, 1/10 of my calculations. Again, BobK right on.

My math did not deter him. And of course he loaded them with 9/8oz. The good news is, shot out of my versamax they're tolerable so he gave me 3 or 4 boxes for crows :)


I think 45 mph is the speed out of the trap, those targets slow down as they fly and gain altitude. Gaining altitude turns kinetic energy into potential energy. By the time they reach the stake behind the opposite house, you could catch them with your hand. The speed at the center stake is probably quite a bit slower than 45 mph, and gets slower still as it moves on. That big ol' concave bottom is not a very aerodynamic shape.

_________________
I finally figured out that lifting your head and not following through can ruin your score in a rifle match also.


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Tue Oct 13, 2020 6:48 pm 
Limited Edition
User avatar

Joined: Sat Aug 01, 2020 11:50 pm
Posts: 355
Location: The wilds of rural central California
A "big ol' concave bottom" isn't very attractive either.

Just sayin'.

tp

_________________
RM, NRA/USCCA RSO, NSSF, and a bunch of other acronyms.
12/30" Browning Citori CX White
12/26" Franchi Affinity 3
12/26" ATI Cavalry (hey, it shoots...usually)


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Wed Oct 14, 2020 4:40 am 
Shooting Instructor
Shooting Instructor

Joined: Wed Apr 28, 2004 9:35 am
Posts: 878
Location: Alabama
Online shotgun ballistics calculator.

List shot size, type of shot, velocity and air temperature.
Shows velocity levels at different ranges and Time of Flight.

Now it gets interesting. Enter all the same data, except use the next larger shot size. Now compare remaining velocities and TOF.
You will be surprised!

Also note:
Factory listed velocity readings are taken at a distance of 3 feet from the muzzle of a 30 inch test barrel.




http://www.ctmuzzleloaders.com/ctml_exp ... stics.html


Top
 Profile  
 
 Post subject: Re: Velocity Change Per Powder Change Increment
PostPosted: Wed Oct 14, 2020 5:52 am 
Limited Edition

Joined: Sat Mar 27, 2010 4:16 pm
Posts: 359
Location: Escanaba, MI
BLE, I'm aware that the targets do not stay at 45mph until they hit the ground. And certainly the same is true for shot pellets. I was trying to keep the calculations in the simple algebra realm rather than move to calculus, none of which I remember :)

Perhaps, since both target and pellets are slowing down, the original calculation isn't too far off. For instance, a station 4 skeet shot is 3-3.5ft of lead in most cases.




Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 17 posts ] 

All times are UTC - 6 hours [ DST ]


Who is online

Registered users: bearman49709, Bing [Bot], birdhunter39, Boch0627, Google [Bot], Google Adsense [Bot], jandat, ninepointer, shacked


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