Re: chamber
lewistt said:
The sabot is taking up space in the bore, resulting in the powder column occupying a larger diameter area than the actual projectile. Take, for instance, the old "accelerator" rounds in a 30-06. By inserting a 22 cal. bullet with a sabot into a standard '06 case, you have what amounts to a .220 swift. This increases the case diameter in relation to the bore. Once the powder goes off, it is irrelevant that the sabot leaves with the bullet. Thicker sabots and smaller diameter pojectiles increase this relationship. I guess engineer types could argue internal ballitics on the way down the bore, but I don't think it makes much practical differnce in the field. More important would be having the proper twist to stabilize the longer projectile. Just for grins, It would be cool to work up a .25 cal. bullet sabot for a .50 cal. muzzleloader! Wonder if it would work!!??? Other wise, I don't see how you could reliably seat the projectile on the powder charge. Air space between the two, in a blackpowder gun, is a bad thing.
I want you to know I really like your posts. I also want you to know some of the things that follow are counter to the ideas you present. Still I don?t claim to be any authority or so smart you can?t prove me wrong. I?m hoping I can say this without it coming off like I?m trying to show you up because ideas like yours are the reason this area of the board exists.
What you say is based on logic and I don't correct someone just because his angle is different from the point I'm trying to make but I still think you are on shaky ground. For instance you say the sabot is simply taking up space in the bore. That it does but by definition since it moves it is the actual projectile: the chamber is a fixed space. For there to be a chamber as we discribe in this post the powder column would have to be larger than the bore not simply wider than the metal portion of the bullet.
You also say it is irrelevant that the sabot moves at ignition. I hope it moves as there will be an explosion if it doesn?t. It is also relevant because it adds to the bullet weight and it itself is a part of the projectile. A 300 grain bullet actually weighs 312 or 313 grains when shot with a sabot and pressure estimates must never ignore this extra weight to arrive at practical results.
Your analogy of the ?accelerator? is also misconceived as it does not amount to a 220 Swift. It amounts to a 30 caliber rifle trying to shoot a grossly underweight bullet. The problems associated with such a venture are reflected by how such a round is nearly in moth balls. Finding ?accelerator? rounds is getting to be a challenge. That?s why shooters who want 220 Swift or 22-250 performance shoot the Swift or the 250, not the 30-06.
You also mention shooting a 25 caliber bullet in a muzzle loader. Though you?re not the first to think of that, I give you the credit for keeping an open mind. Several have worked for a smaller caliber bullet. Mark Edgerton, Steve White, Dave Daub, and Terry Krebs have been invaluable help to me in deciding how to shoot sub-caliber bullets in a big bore rifle.
Terry, Steve, and Dave have tested a long line of 45 caliber rifles shooting 40 caliber bullets. All of us have been able to exceed 2600fps with a 200 grain bullet with serious accuracy. These rifles use off the shelf components everyone can obtain. Mark Edgerton has a unique way to machine sabots with the rifling engraved on the outer surface . With this system he is able to shoot bullets as small as 8mm (.323 caliber 150 grain) at speeds equal to any rifle of this caliber. The problem with the process is it takes machining work that?s too expensive for the average shooter.
Using one of these methods to shoot a 25 caliber bullet is unlikely. First the rifle would have to be re-barreled because a 25 caliber bullet will never shoot in the slow twist barrels presently used in a muzzle loader. Another problem is ?Rick?s Rule? which states the smaller the bullet compared to the bore the harder it is to shoot in a sabot. I won?t rule out 25 caliber accuracy from a muzzle loader but it would have to come from a dedicated system. A regular 50 caliber barrel has too many problems to overcome.
One last thing: since we are shooting smokeless powder here (all this area is about smokeless shooting but we will talk BP at times) air space in the powder is not as much a worry as in BP shooting. Smokeless will be harder to ignite with an air space but that's the worse thing that can happen. There is no safey problem: the rifle will either shoot or not shoot.