The Firing Line Forums

Go Back   The Firing Line Forums > The North Corral > Black Powder and Cowboy Action Shooting

Reply
 
Thread Tools
Old March 20, 2009, 08:57 AM   #1
tpcollins
Senior Member
 
Join Date: February 18, 2009
Location: SE Michigan
Posts: 443
How soon does a sabot start to spin?

A bullet from a centerfire jumps froms the case into the rifling and I would assume it will start to spin immediately. A muzzleloader sabot relies on the lower skirt to expand into the grooves to impart spin.

It would seem logical that when the powder explodes, the sabot would move forward some amount before the skirt gets expanded into the grooves to get it spinning. When loaded, the sabot sits about 22" away from the muzzle on my MK85. How soon does the sabot start to follow the 1-28" twist?

Back in the day of slower twist ML, the old patched ball was pretty darn accurate. I wonder if anyone ever took a .45 rifle bullet with the right thickness of patch and seated it into the grooves to get it to spin when fired? I would of thought by now somebody would have a sabot like a spline that would "screw" into the barrel's grooves to impart spin immediately.

Last edited by tpcollins; March 20, 2009 at 11:42 AM.
tpcollins is offline  
Old March 20, 2009, 09:28 AM   #2
jaguarxk120
Senior Member
 
Join Date: February 28, 2008
Location: Michigan
Posts: 1,943
The sabot will engage the rifling as soon as pressure builds to expand the skirt into it. And please gun powder burns, it does not explode!
jaguarxk120 is online now  
Old March 20, 2009, 09:44 AM   #3
mykeal
Senior Member
 
Join Date: October 8, 2006
Location: Northern Michigan
Posts: 2,758
tpcollins - you're assuming the sabot/bullet combination starts to move immediately as the gas pressure rises. If that were true the sabot would never expand. Jaguarxk120 has it right: the first thing that happens is the sabot starts to deform as soon as the gas pressure starts to build. The resistance of the malleable plastic sabot to deformation is significantly less than the mass/inertia of the sabot/bullet combination, so the sabot expands first. Once it reaches the limit of expansion as determined by the geometry of the barrel (including the rifling) then the gas pressure begins to move the sabot/bullet.
mykeal is offline  
Old March 20, 2009, 11:27 AM   #4
Pahoo
Senior Member
 
Join Date: February 16, 2006
Location: IOWA
Posts: 5,577
TP,
One day I will get off this learning curve and every day is not disappointing. Given that, I really have to ask what is behind this question? Is there a concern? I have shot just about everything there is out of an M/L and this has never come to mind. Can't keep up with all that comes down the pike as to what is shot out of an in-line, nor do I really care to. Have worked up good loads for my use that have met or exceeded all my expectations.

Please excuse me for asking but, Why do you ask this question??


Be Safe !!!
Pahoo is offline  
Old March 20, 2009, 12:07 PM   #5
tpcollins
Senior Member
 
Join Date: February 18, 2009
Location: SE Michigan
Posts: 443
Pahoo - being retired and bored at the same time this winter, I decided to get into reloading specifically for coyote hunting with my .243. With the help of the reloading section of this forum, I've managed to load some rounds with reasonable results at the range. (I've had some disapointments as well but I think that has more to due with my unstable rifle rest than my loads).

I use my muzzleloader in the shotgun only areas here in Michigan. I shoot the lighter 180 gr Precision Rifle sabots (.40 cal bullet) and am pleased with them. Over the winter I bought some of their 195 gr Duplex sabots (.357 bullet) that are cased in a special flat base .45 cal sabot and then this gets put into a .50 cal sabot. These dual (Duplex) sabots supposedly achieved the flattest trajectories and tightest shot groups by an independent tester but I'll have to see for myself to know for sure.

So as I sit here waiting for turkey and golf seasons to start, I am constantly trying to understand how to improve the accuracy of my firearms. Understanding how the bullet jumps into the lands from the reloading forum got me thinking about how soon a sabot starts to spin - which is needed for accuracy. I realize I should have said burn instead of explode and you probably thought I could have been a terrorist in hiding - I'm not. And I voted for McCain mainly because of Palin.
tpcollins is offline  
Old March 20, 2009, 12:40 PM   #6
Pahoo
Senior Member
 
Join Date: February 16, 2006
Location: IOWA
Posts: 5,577
Quote:
I am constantly trying to understand how to improve the accuracy of my firearms. Understanding how the bullet jumps into the lands from the reloading forum got me thinking about how soon a sabot starts to spin - which is needed for accuracy.
I can appreciate that as it is no more than any of us are trying to do.

Quote:
probably thought I could have been a terrorist in hiding - I'm not.
Thought no such thing but you know, I'm sure there are some out there that use M/L's. Last week, was checked at the door at a local G.S. by a cop. Had an M/L with me and told him I was looking for a high capacity mag for it. He appreciated the humor but then again, he knows me well. Hey, he still put a tag on it !!

Quote:
And I voted for McCain mainly because of Palin.
Gees, you are going to open up a can of worms with that one. Have to say that I voted for McCain because of Obomanation. Getting tired of voting by who I don't like rather than who I do like .....

Be Safe !!!
Pahoo is offline  
Old March 20, 2009, 01:15 PM   #7
tpcollins
Senior Member
 
Join Date: February 18, 2009
Location: SE Michigan
Posts: 443
"Please excuse me for asking but, Why do you ask this question??"



Why did you have to bold and highlight the question in this manner?
tpcollins is offline  
Old March 20, 2009, 01:20 PM   #8
Pahoo
Senior Member
 
Join Date: February 16, 2006
Location: IOWA
Posts: 5,577
For the same reason I bold anything; It's easier for me and others, to read and no, I didn't have to.

Be Safe !!!
Pahoo is offline  
Old March 20, 2009, 02:55 PM   #9
4V50 Gary
Staff
 
Join Date: November 2, 1998
Location: Colorado
Posts: 16,837
Let's sing Kumbaya and not get into hissy fits about bold or colors. We're all men of the black powder and this should be like an on-line rendezvous.
__________________
Vigilantibus et non dormientibus jura subveniunt. Molon Labe!
4V50 Gary is offline  
Old March 20, 2009, 08:46 PM   #10
kirpi97
Senior Member
 
Join Date: November 20, 2008
Location: Oregon
Posts: 236
Now let's all hold hands and sing together...

Kumbaya my lord, kumbaya
Kumbaya my lord, kumbaya
Kumbaya my lord, kumbaya
Oh lord, kumbaya

Someones singing lord, kumbaya
Someones singing lord, kumbaya
Someones singing lord, kumbaya
Oh lord, kumbayah

Someones laughing, lord, kumbaya
Someones laughing, lord, kumbaya
Someones laughing, lord, kumbaya
Oh lord, kumbaya

Someones crying, lord, kumbaya
Someones crying, lord, kumbaya
Someones crying, lord, kumbaya
Oh lord, kumbaya

Someones praying, lord, kumbaya
Someones praying, lord, kumbaya
Someones praying, lord, kumbaya
Oh lord, kumbaya

Someones sleeping, lord, kumbaya
Someones sleeping, lord, kumbaya
Someones sleeping, lord, kumbaya
Oh lord, kumbaya
Oh lord, kumbaya

I don know about all of you, but I feel a lot better now.

And we must not forget, there are women of the black powder as well. We must always remain "politically correct" around here.
__________________
The parting shot...
"Those who hammer their guns into plows, will plow for those who do not." Thomas Jefferson
kirpi97 is offline  
Old March 21, 2009, 03:09 PM   #11
tpcollins
Senior Member
 
Join Date: February 18, 2009
Location: SE Michigan
Posts: 443
Thanks mykeal, that really makes sense.

Now for another can o' worms, what's your thought on the higher pressure created by a 209 primer moving the sabot forward slightly before the powder has a chance to fully BURN as compared to the less pressure from a #11 percusion cap? Thanks.
tpcollins is offline  
Old March 21, 2009, 04:10 PM   #12
Pahoo
Senior Member
 
Join Date: February 16, 2006
Location: IOWA
Posts: 5,577
Quote:
Now for another can o' worms, what's your thought on the higher pressure created by a 209 primer moving the sabot forward slightly before the powder has a chance to fully BURN as compared to the less pressure from a #11 percusion cap? Thanks
Some might argue this point but it is true and there are a couple of approaches to a "Fix".
  • Puchase reduced power 209's. Some are now labled as such. Remington comes to mind as well as Winchester. You might see a lable like "M/L 209's or some such thing.
  • Another is to use a Musket Primer or Top-Hat.
  • Then there is the CVA Electra which produces no pressure but will ignite the main charge.
On my Traditionals, I stick with a #11 and on my Hunter In-line, I shoot a Musket primer. But my In-Lijne is an open breech type. Truly believe that whatever folks choose as their "Shot String" they learn to work and live with it. Personally I see no reason for this child to switch to a 209. I teach them but don't use them. Just me ...

Be Safe !!!
Pahoo is offline  
Old March 21, 2009, 05:53 PM   #13
mykeal
Senior Member
 
Join Date: October 8, 2006
Location: Northern Michigan
Posts: 2,758
The higher pressure output of a 209 primer is simply seen as a force at the powder/sabot interface, just like the gas pressure from ignited powder. It will expand the sabot before moving it also.
mykeal is offline  
Old March 21, 2009, 09:00 PM   #14
tpcollins
Senior Member
 
Join Date: February 18, 2009
Location: SE Michigan
Posts: 443
I dont want to start a pi$$ing contst but has this been observed by some type of see-thru barrel apparatus with a slow motion camera or is this from a physics professor's calculations on a blackboard?

You can put a patch over a jag on a cleaning rod up against the breech plug, fire a 209 primer, and the cleaning rod will move quite a ways back up the barrel. To me that seems like a lot of pressure that wants to go somewhere in a hurry, but if Mr Sabot doesn't move until after his skirt gets spread into the rifling first, then that's really good information to know.
__________________
What direction did that last shot at Kennedy come from?
tpcollins is offline  
Old March 21, 2009, 11:11 PM   #15
arcticap
Senior Member
 
Join Date: March 15, 2005
Location: Central Connecticut
Posts: 2,973
Quote:
A muzzleloader sabot relies on the lower skirt to expand into the grooves to impart spin.
I think that the wall of most every sabot fit tight enough in the bore that they do not need to rely on the expansion of the base to begin spinning. Thus they would begin to spin immediately upon movement.
The walls of the sabot also slightly bulge out when the bullet is simply inserted into it, and this helps sabots to fill the barrel grooves and to spin even as it is rammed down into the breech without the skirt being expanded.
There are some looser fitting sabots and I don't know if it takes any longer for them to begin spinning in some bores or not, but they are said to load and shoot better out of some guns with tighter bores.
Also, the TC Break-O-Way sabots don't have a hollow base skirt but a flat wool wad base which I don't believe is even required for them to begin spinning since the sabot wall is plenty tight. The skirt may help to create more consisent and higher velocity and maybe even more RPM's in flight, but is not really necessary to impart an earlier spin.

Last edited by arcticap; March 22, 2009 at 08:26 PM.
arcticap is offline  
Old March 22, 2009, 09:59 AM   #16
tpcollins
Senior Member
 
Join Date: February 18, 2009
Location: SE Michigan
Posts: 443
Well, well . . . .

Here is one article on the excess pressure from a 209 primer unseating the sabot prior to powder burn. If there wasn't some truth to it then they wouldn't have come out with the new "low pressure 209 primers". Another article reminded me the reason for using the 209 primer was to ensure the ignition requirements for the new powder "pellets" that came out. My biggest issue was always the 209 breech plug design - this can't help accuracy.

http://www.hpmuzzleloading.com/Technical3.html
__________________
What direction did that last shot at Kennedy come from?
tpcollins is offline  
Old March 22, 2009, 11:47 AM   #17
simonkenton
Senior Member
 
Join Date: April 25, 2008
Posts: 891
The sabot spins when you load it. I can feel, and see, my ramrod turning as I load the sabot.
The rifling engraves the sabot as it is rammed down on to the powder.
Thus, the sabot must begin spinning, again, as soon as it begins moving down the barrel when the trigger is pulled.
simonkenton is offline  
Old March 22, 2009, 08:29 PM   #18
L'derry
Member
 
Join Date: November 6, 2008
Location: NH
Posts: 63
Not all brands and types of sabots are created equal. Therefore I don't think a statement can be made that THE sabot starts to spin immediately or it moves 1/4' up the barrel before it starts to spin.

And frankly, I for one don't - and not sure why anyone would - care as long as I work up a sabot/powder combo that gets the best accuracy for my specific ML.
L'derry is offline  
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 03:02 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.10475 seconds with 9 queries