I am pasting my response to another thread on sabots here to make it easier for me to track. Please take the time to comment and question as this has potential business applications. Thank you.

Gentlemen -

You can see from my handle that I have more than a casual interest in sabots. I have a ballistics lab and have spent over 3000 hours sorting out the good and bad of sabots for small arms applications. I plan to open a specific topic on sabots, but suffice it to say:

1. Properly loaded 224/308 caliber sabots shoot the same MOA as the parent cartridge in a given rifle..

2. The wild variations in velocity and accuracy are due to the fact that there are few propellants on the market today that have burn characteristics suitable for shooting 224 bullets in 308 barrels. Most propellants do not work well because pressure drop after ignition is dramatic and unpredictable.

3. Thin sabots holding bullets heavy enough to eliminate rapid pressure drop and make a broader range of powders applicable will shoot smaller MOA than the parent cartridge in a given rifle. Thin sabots do not need to be as stiff and hard as thick ones, and have much less influence on the bullet as they peel of...they actually "detonate" off.

Example: 30-06 shooting 100 gr 6MM bullets. From an internal ballistic perspective, these loads behave very much like moly coated bullets, i.e., when reduced pressure is offset by increased charge weight velocity exceeds loading manual data at safe pressures. Max loads for the '06 for ANY 110 gr bullet may be used as start loads for the 100 gr sabot application.

4. Properly sized and designed sabots nearly eliminate barrel fouling when heavier bullets are used and held to 3700 fps. New compositions will extend the velocity range.

5. The most appropriate application of thin sabots to small arms is to increase the sectional density of the lighter bullets currently used in the firearm. For example, the 6MM 100 gr application to the '06 provides a 60% increase in SD with ballistic coefficient to match. To match the 3500 fps delivered by the '06 in a 22 inch barrel, a 6MM rifle needs 30% more powder and a 29 inch barrel. In this manner, a smaller case can match a larger case when bullet diameter is held constant. A 338 Win Mag, shooting 180 gr .308 bullets can, and does, match the external ballistics of the 300 RUM with 2 inches less bbl and yeilding a 30% reduction in recoil. My 338 RUM launches 180 gr flat based .308 spitzers at 3600 fps and 220 gr SMPs at 3230 fps, both achieving 0.50 MOA. I am a slightly better than average shot. In the hands of an experienced 1000 yard shooter, and with a custom throat I have designed this round will be competitive in 1000 yard matches and has the potential do dominate it after skilled accuracy buffs work with it.

NOTE: This sabot is only 10% larger than the bullet and uses a scored tear away design instead of the typical petals. Very thin petals will "squirm" in the rifling and may not impart full rotation rates. Its more like a very tough patch that peels instead of unwraps. The sabot covers the full length of the bullet with the the diameter dropping from .3385 to .330 at he point where the ogive decreases bullet diameter. They are chambered by hand and do not cycle well. Sabots this thin are poor choices for hunting except with single shot rifles. A 6.5MM/338, .270/338 or 7MM/338 sabot is better if the action is to be cycled. The 6.5 and 7MM will need a custom bbl with 8 to 9.5 inch twist rate, however.

6. The sabot reloading market can easily include kits allowing the reloader to form excellent sabots using moulds and form dies. The specific bullet to be fired can be used in the forming process, as can the throat of the rifle that it will be chambered in. The point of contact with the lands is controlled by the sabot design.

7. Sabots make bullet shape and jackets into EXTERNAL ballistic factors unconstrained by the rigorous requirements of bores and rifling. Unlubed lead bullets work fine. Note: lubed lead bullets at high velocities sometimes look like tracers. The cost of non-jacketed lead or composite bullet, complete with sabot, will be far less that today's jacketed bullets.

8. Sabot kits, as well as finished retail sabots, can easily be designed to make them a very poor choice for criminal activity. Hopefully this will overcome BATF objections to sabots in general. It takes me 20 minutes to an hour to find an expelled sabot on the ground, they give fine detail of rifling engraving, and they can stamp the base of the bullet with a code when fired. Any nitro sniffing dog can find one in 1 minute.

Hopefully my pontification has not bored any of you, but I confess to being something of a sabot nut, just as some of you are gun nuts. Aside from the technical advantages of thin sabots, its just plain fun to work with them.

Sabot,

Maybe you can come up with a sabot with a cannelure, with a crimp, the burning should be more consistent.

I believe sabots allow use of bullets that are even more streamlined than boat-tail. And since the bullet inside the sabot is NOT engraved and disturbed by riflings, the bullet itself should be more accurate and can be made with any material other than lead ---brass, copper, even steel. A brass bullet turned on a lathe would have no concentricity problems, geometry wise or weight wise, provided there are no bubbles in the metal.

Imagine, a slender, long perfect brass bullet with high BC that is shot out of a quick-twist barrel at high speed, there's no worry of bullet spinning apart because the bullet is one piece of metal.

That sounds like long-range precision to me.

Something comes up in mind :

The reason we use metal jacketed bullets are :

1.
The jacket helps the bullet glide without lead fouling.

2.
The jacket protects the base of bullet as it leaves the bore so it's not deformed by venting of powder gas.

3.
Special designed jackets modify the expansion characteristics of bullets in terminal ballistics.

4.
The jacket protects the bullet shape.

Well, reason no.3 exists for hunting bullets while reason no.1 and 2 are fundamental reasons. Now if sabots serve the purpose of no.1 and 2, it means in target shooting, a bullet without jacket can be used at regular high speed which means less cost than jacketed bullets.

Pyrotek -

Thanks for the fast response. Conditions 1 and 2 are, in fact met. Sabots made from the right composite virtually eliminate fouling up to 3700 fps, and a little research will expand this envelope. The square bases are highly flame resistant and totally insulate the base of the bullet from expanding gasses. Any strong composite that will not melt in a 400 degree F flame in 1 minute will "take the heat" it is exposed to in a few microseconds. The sharp edges on the sabot bases do become a bit rounded. Thick sabots release about 14 inches from the muzzle and thin sabots release from 3 to 6 inches depending on design.

I like the crimping groove idea. To date, I ahve only worked with standard roll crimps and sometings a factor crimp die. Crimping pressure is important as it is very easy to compress the composite material and change ignition characteristics. A aepered groove matching the taper of the die, would help sovle this problem. Most cases need to be very slightly belled to aviod shaving the sides of the sabot as it is seated. An impact type of bullet puller will NOT budge them...they are IN there.

Special abrasive sabots can be used for bore lapping, and copper bases may work like copper crushers to measure peak pressure. Because they do not conduct electricity, and copper jackets do, there is a potential to insert primers into the base of the sabot and ignite them electronically. This would probobly require a ceramic throat insert. Military research has shown that this type of ignition can boost velocity by 6% at a given pressure level.

I've often wonders if a pre-engraved slug wouldn't work better in a sabot. Heck I first thought of it years ago in reference to the Oswald-Kennedy bruhaha. A 6.5mm prerifled slug from a 308.

Very intelligent thought...it was a 120 gr 6.5, and short enough to stabilize in the .308.

If they had used one of the sabots we are proposing they would have been caught red handed and there would have been one resting in the grass on the Grassy Knoll.

VERY INTERESTING!

WHAT IS THE OTHER THREAD ON SABOTS YOU REFERENCED?

Sounds like a variation on paper patching.

I assume the kit you mention would be an injection moulding machine with the appropriate moulds. Interesting idea, if i get chance over the summer I'll make something up to test. Do you have a preferred material? I will probably use high density polyethylene.

Where is this other thread you refer too?

The other thread is by Cooch on 6-1, second page of this thread.

Our friend from England has put me in a tough spot ethically speaking because I have a plastics/resin manufacturer as a potential partner in this as a business venture, and they have been good about helping me with compounds and forming techniques. We have non-disclosure agreements on composition and forming.

Thin sabots are not likely to be a cottage industry, but will be sold or licensed to an established ammo or reloading components firm. Composition and forming technique is very important, and probably the only intellectual property peg we can hang out hat on.

On the other hand, I don't want anyone to damage a barrel by experimenting with the wrong materials. You can gum up the barrel with material that hardens quickly and pressures will spike. You can also push the bullet out of the barrel and ring it with the sabot by blowing through the base...this is very dangerous if you fire a subsequent round and quite a mess to clean out. If you do work with new materials, inspect the barrel after every round.

My suggestion is to get some experience with commercial .224/.308 sabots first, before moving into larger bullet diameters and thinner materials. If your .308 caliber rifle has a long throat, you may not get the best accuracy. My best test beds have been Savage 110s.

Wow - very interesting work! I wonder how feasible it would be to make a scaled-down version of a fin-stabilized projectile to shoot from a smoothbore .45 - .50 caliber barrel? Get the velocity up around 5000 fps and use a brass dart that tumbles on impact... Scale down the tank gun rounds for hunting

I have a bag of 500 sabots from J and D Components www.jdcomponents.com out in Orem, Utah. He says he makes many, many thousands of them a year in multiple calibers. Do you have any experience with his products; I've yet to load up and shoot any. Good prices and quick turn-around, but he's not set up for credit card orders. Call him at (801)225-7007 after 1700 Utah time. 500 22/308 sabots are $33.50 delivered by USPS and they get cheaper the more you buy.

[ 07-05-2003, 14:59: Message edited by: rootbeer ]

Sounds good I have said for a long time some one should come out with sabots for many differant cailbers. I belive that there is a market in the reloading community for these. A 338 308 a 45 338 ect.