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Post by hornet22savage on Jul 1, 2011 18:20:50 GMT -5
With out knowing the exact reason you are using such a hard material, I'm guessing it ahs to do with the rate of twist and pressure or speed of the load. Have you though of using a duplex sabot? Somthing like the precison rifle duplex sabots for 50x357? Use an existing 50x45 sabot and then make an insert for the 30 cal. bullet. This would aslo be pretty universal.
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Post by littlejoe on Jul 1, 2011 19:04:58 GMT -5
Edge, I will look into the cost on Tuesday when the shop supervisor gets back. I am sure there are some pieces at the shipyard I could send you for free to try. I assume rod form is what you would need 1/2" dia. I will try to get a price for the different grades. Joe
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Post by edge on Jul 1, 2011 19:53:44 GMT -5
With out knowing the exact reason you are using such a hard material, I'm guessing it ahs to do with the rate of twist and pressure or speed of the load. Have you though of using a duplex sabot? Somthing like the precison rifle duplex sabots for 50x357? Use an existing 50x45 sabot and then make an insert for the 30 cal. bullet. This would aslo be pretty universal. You need a rigid material to keep the bullet centered in the bore and the smaller the diameter and the shorter the bearing length the more important it becomes. Duplexing sabots is not new, but it just adds another piece of flexible material into the mix. I use to use a machined inner sabot with a 180 grain 35 caliber bullet. It was pretty accurate but nothing like the 1 piece rigid sabots. edge. |
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Post by hornet22savage on Jul 1, 2011 20:06:22 GMT -5
Ok I was just wondering, since it seems like a pain to have to rifle each and every sabot just to load them. I though that you could make a rigid insert and load that into a flexible sabot and that eliminates the need to rifle the sabots and makes it more universal. just a thought but if your ultimate goal is accuracy then your right and I'm rambling. If you were to consider using a duplex you could also use the lightfield two piece design for the inner insert.
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Post by edge on Jul 1, 2011 20:50:43 GMT -5
Here was how I did it a loooong time ago   The bullet is a Hornady 180 grain SSP. edge. |
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Post by hornet22savage on Jul 1, 2011 20:55:58 GMT -5
That looks good how was the accuracy and performance of that design? What is tha caliber of the bullet. I would like to try the Precision Rilfe duplex sabot but don't want to have to buy their bullets just the sabot and add my own bullets.
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Post by edge on Jul 1, 2011 21:41:47 GMT -5
.358 diameter. I think that the PR duplex sabots are both soft plastic. I am 99.9% others have tried that route already. Here was an old post from the old board: SNIP Edge, were you using a duplex sabot or PR's .50/35 sabot when you found success with the 180 SSP? Unfortunately, this took place before this board was around, on OL'Green, so the original thread is not here. I have written about it in the past so I'll just quote that  Back on Old Green, I posted about shooting a buck on the last day of the season 2004 shooting a 35 caliber 180 grain Hornady SSP with my Savage.
This was using a Harvester 50 sabot and nylon inner sabot and an aluminum disk/washer inside the Harvester sabot:
The two main problems with shooting sub 45 caliber bullets is the lack of support at the base and sides of the bullet.
PE type plastics are just not strong enough to overcome the inertia of the bullet, and once the sabot stretches, even a very little bit, you will drill the sabot.
Back in 2004 I likened this to you standing next to a race car and holding onto the bumper. When the light turns green the car accelerates. If you are holing on then you are dragged down the strip, if you let go, even for a fraction of a second, you can never catch the bumper again. If you were a bullet inside of a sabot, you just made a hole in the sabot base, drilled the sabot!
So now the problem is twofold, support the base, AND now with a much thicker section of plastic between the bullet and bore ( not to mention a reduced bearing surfaces, prevent the yawing of the bullet in the bore.
IMO, this requires a rigid inner sabot or a totally rigid sabot. The inner sabot is most likely the only way to do this on a mass scale due the differences with bore diameters.
edge.
The results:
entrance and exit: |
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Post by hornet22savage on Jul 1, 2011 22:25:57 GMT -5
I understand the theory of the smaller bullet and what not it's really just inertia. it takes so much force to more the bullet without proper support the sabot goes around it. My question is, does this happen with subs too or just smokeless. Not to get thing misconstrued I'm shooting a Knight KRB whch has a modified breech plug to shot BH209. I know I'm on the smokeless thread but this has my intrest. I'm looking push a smaller bullet faster and flatter for woodchucks while not spending a fortune in the process. the 50x357 seems like a good route to go, but the PR bullets are so expensive I can't justify the cost.
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Post by mountainam on Jul 2, 2011 7:11:51 GMT -5
hornet, PR sells the .50x.357 alone. I used them with Hornady .357 180gr XTP's at 2281fps and Hornady 200gr RN .358" at 2201fps, BUT Smokeless will drill them subs will not. You can click on the crosshairs on PR Bullet's site and buy the empty sabots there. Keep in mind they are made by MMP for them and MMPsabots seem to be made from a more "gummy" plastic that can drill easier than do Harvesters, but the PR sabot has nice long petals.
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Post by rossman40 on Jul 5, 2011 21:18:31 GMT -5
As Edge can tell you there are so many plastics out there and then it is complicated by trade names. Then you have fillers and other additives. The term "Elastomer polymer" sounds like salesman BS. A elastomer is a polymer that has the property of elasticity.
We used some wild stuff (Torlon IIRC) to make replacement bushings that cost over $200 a foot for a 2" rod 10 years ago. If you think that is expensive look at Vespel which a 1/2" rod will cost you like a $1000 per foot. And then there is another one that DuPont makes that if you have to ask the price you don't need it.
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Post by littlejoe on Jul 7, 2011 10:07:28 GMT -5
I talked with my old supervisor today. He said he believes Thordon expands and contracts due to temperature too much to work as a sabot material. Edge gets a +1 from him as Delrin probably being the best choice. He did say playing with different colors may have subtle differences in results or they may not.
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Post by rossman40 on Jul 9, 2011 13:55:55 GMT -5
Looking thru some of the old patent data I found this from Olin (Winchester) in US patent 4,653,404 March 31, 1987,
said sabot being of a plastic material having compressive strength of at least 15,000 psi as measured by ASTM Test Method D695 and shear strength of at least 12,000 psi as measured by ASTM Test Method D732 to withstand the compressive and shear forces of explosive discharge through said barrel while carrying the projectile in said recess and having an impact notch strength of less than 12 ft-lbs/inch as measured by ASTM Test Method D256 in the portion of the wall between the rear pointed ends of the grooves and the base of the sabot to withstand the sudden application of aerodynamic and centrifugal forces to the wall following the discharge so that after the discharge the wall immediately and substantially simultaneously splits at each groove and the wall segments separate from the base to thereby free the projectile for further flight and whereby the weakened portion of the projection can prior to discharge assist in obturation of the barrel.
Another interesting detail from Remington, US patent 6,073,560 June 13, 2000,
The practice of the present invention includes fabricating the sabot from any suitable material. Preferably the sabot is manufactured from plastic with linear low density polyethylene (LLDE). LLDE has excellent toughness, physical properties and engraving characteristics with barrel rifling. For example, upon firing, the sabot will obturate at the base engraving the rifling and imparting spin to the projectile/sabot system. The LLDE material will also flex along the sabot's peripheral side walls upon loading. This produces the force the shooter must supply to the projectile/sabot system via the ram rod when seating the system on the powder charge. Constructed in such a manner, a projectile is loaded into the sabot by peeling back or stretching slightly the front section 12 of the sabot, and inserting the projectile within the cavity 40. The elastic properties of the sabot allow the front section to return to an encapsulated state. Although a wide variety of plastic fabrication techniques may be employed to manufacture the sabot, injection molding is a preferred technique, thus resulting in a one piece or unitary construction. Such a construction greatly simplifies the manufacture of the sabot and reduces costs.
Another newer one from Winchester, US patent 6564720 20 May, 2003,
Preferred material for the sabot body is a high density polyethylene (e.g., 94% HDPE, 6% impact modifier). An exemplary impact modifier is a very low density linear low density polyethylene (VLDLLDPE) sold by DuPont Dow Elastomers, LLC, Wilmington, Del., under the trademark Engage 8200NT. The desirable properties of this plastic include cold temperature flexibility and softness. Cold temperature flexibility assists in keeping the petals attached to the sabot base during muzzle exit when firing cartridges (shells) subjected to cold temperature storage. A relative soft plastic is desirable to permit material flow and deformation to avoid potential barrel damage.
Fuel for thought.....What is mentioned may not work for thicker sabots like Edge is making for a .338/.50 sabot. Along the line of HDPE would UHMW work? I have used that for machining bushings and seems a tad better then Delrin.
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Post by Jon on Jul 9, 2011 18:43:35 GMT -5
Roseman. I've asked the same question I've had great luck with uhmw For differant applications. So I'm only talking apples to tomatoes. But it didn't seem of interest to people involeved.
Jon
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Post by rossman40 on Jul 9, 2011 21:43:47 GMT -5
I do not think you can machine a .45/.50 sabot and keep decent tolerances with the softer plastics. Edges work shooting the .338 bullets I would think you would need a stiffer plastic due to the thickness. UMHW might work for thinner sabots but Delrin is a bit harder from what I can tell and looking at pieces I have it seems that way. Then there are different formulations which may have advantages.
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