The Sabot Saga Continues

[Rick Teal]

I went to the range today to try out loads for my CVA Optima in .45 Calibre

I bought this rifle so I could hunt with some of the .35 calibre bullets I swage, during the ML season. 

Originally, I had bought some Hornady sabots designed for use with .357 and 9mm pistol bullets.  When I tried these out last year, my bullets key-holed and were all over the paper.  I made some shorter bullets, and when they didn't work, made a different type of bullet that was shorter by necessity.  I still met failure.

I searched the web to see if there was an alternate source of sabots to no avail.

I then decided to buy some 40/45 sabots and build them up some way to make them grip my .35 calibre bullets.  Today was my first attempt.  I used cloth patching that was .011 thick, doubled it over and wrapped it arount the bullet inside the sabot, making effectively a thickness of .044, which with my .358 bullets should make a diameter of .402.

I set out with 3 bullet designs all set up in these sabots, and was met with universal failure.  When I could find the impact points the bullets were all sideways.

I scrubbed that project for now, and proceded to sight the rifle in using power Belt bullets, and it shot like a charm.

I'm thinking of painting the inside of the sabot with something like liquid paper or nail polish.

[talon]

Rick,
   Could it be that the BC, speed and rate of spin of a 35 cal slug makes it impossible to stabilize in a .45cal BP barrel, regardless of the method used to 'sabot-ize' it? Maybe someone who has some background in internal ballistics could explain the theory here.

[Rick Teal]

Talon:

The bullet length/twist rate was the first thing that occurred to me, but I can't imagine that they make 35/45 sabots - even for pistol bullets - if they don't work.

In order to resolve this, maybe I should make some "virtually pointless" bullets that would be almost like cylinders, and see if they will stabilize at about 150 grains which is within the recomended weight range of 150 - 180 for 35/45s.  If I get round holes with those, it would mean that my project is probably hopeless.

[toysoldier]

I was wandering around the forum and ran across this. My suggestion is that the slug is NOT being rotated by the sabot, especially the patched one. 

[Rick Teal]

You're likely right on that point.  Since this thread was running, I spoke with the guy at PR bullets, and he's of the opinion that a bullet should have no more than a 2S ogive to stabilize in a 45/35 sabot.  This would leave my 4S bullets out in the cold.  When I can get back to this project, I plan to try the cylinder (or near cylinder) thing and see if that works.  I have a bullet design in mind that might work at short range with this type of tip.

[wgr]

ive tried lead bullets in sabtos and found that soft bullets like pure lead dont shoot well in a sabot. all your lead saboted bullets are hard. i have a friend that shot some 158 grain jhp  out of a 1in 48 twist and got one hole at 80 yards. in my 1in 30 and 1in 28 i get 1 to 1/2 in groups at 100yards with 250grain xtp bullets  with  bullet cast from   ww  out of a 45long colt mould i can get 2 to 3 in groups at 100yards . use soft lead and im lucky to get 8in at 100. lately ive started paper patching all my hunting bullets. they load easy like a power belt  hit as hard  good groups  and alot cheaper

[shakey]

You are not by any chance using REDUCED charges are you ?

Less velocity = Less spin

Just checkin'.

[Rick Teal]

I'm shooting two pyrodex pellets rather than the maximum load of 3, however, its my understanding that the effect of the twist rate is consistent throughout the range of velocities.  My 1:28 will still turn once every 28" regardless of velocity or the RPMs of the bullet in flight.

You've given me food for thought though, and I think I'll look into this issue more deeply.

[Smokin Joe]

Rick, the RPM rate increases as the velocity increases. More velocity = faster spinning slug, and maybe better stability.

[GREYGHOSTt]

yes you need to increase the velocity for example
i can shoot 69 sierria's in my 220 swift if i molly them and really pump them up but at low starting load vel. they keyhole!!