Rayleigh_Scattering
Regular
- Location
- Under the arch
I'm mulling something over in my head...
The steel core Bulgarian 7.62x54R I use as a "reference geometry" has a long 150gr boat tail projectile.
The 150gr lead core commercial projectiles I see for sale are shorter, and have a flat back. I suppose that makes sense, as the Bulgarians are steel core and it takes a larger volume of steel to produce the weight, and since diameter is fixed the larger volume comes out as length.
To get an acceptable "about one diameter" of neck grip with the commercial ones I have to move the lead core projectiles back and end up with a much shorter OAL. That put the ogive far back from the leade, and I note that my primers are flattened and cratered even with a middle-of-the-range load (so I've not left enough case volume). There is also a worrysome amount of room at the front of the magazine for things to slide around.
From the fit point of view, the magazine and chamber geometry appear to have been sized for the steel cored 150gr projectile, but I understand the use of steel cores to far more recent than the 1940s.
My question is, what did the Soviets (and I suppose the Russians before them) originally do for these?
Were the Mosin/SVT originally designed for 180ish gr lead projectiles, with the powder load reduced at the same time the steel cores came in to keep the external ballistics close to the same? Better drag coefficient compensating for lower sectional density?
If I want to produce something geometrically like the reference Bulgarian surplus, do I have to go steel core to keep 150gr? Or should I go with a 174gr projectile and a lower/slower powder loading?
If the SVT was designed for 150gr, and given that it already spaghetti-barrels with 150gr, is 174g going to go where I want it to?
To quote the great Vinnie Jones: "Now please, enlighten me."
The steel core Bulgarian 7.62x54R I use as a "reference geometry" has a long 150gr boat tail projectile.
The 150gr lead core commercial projectiles I see for sale are shorter, and have a flat back. I suppose that makes sense, as the Bulgarians are steel core and it takes a larger volume of steel to produce the weight, and since diameter is fixed the larger volume comes out as length.
To get an acceptable "about one diameter" of neck grip with the commercial ones I have to move the lead core projectiles back and end up with a much shorter OAL. That put the ogive far back from the leade, and I note that my primers are flattened and cratered even with a middle-of-the-range load (so I've not left enough case volume). There is also a worrysome amount of room at the front of the magazine for things to slide around.
From the fit point of view, the magazine and chamber geometry appear to have been sized for the steel cored 150gr projectile, but I understand the use of steel cores to far more recent than the 1940s.
My question is, what did the Soviets (and I suppose the Russians before them) originally do for these?
Were the Mosin/SVT originally designed for 180ish gr lead projectiles, with the powder load reduced at the same time the steel cores came in to keep the external ballistics close to the same? Better drag coefficient compensating for lower sectional density?
If I want to produce something geometrically like the reference Bulgarian surplus, do I have to go steel core to keep 150gr? Or should I go with a 174gr projectile and a lower/slower powder loading?
If the SVT was designed for 150gr, and given that it already spaghetti-barrels with 150gr, is 174g going to go where I want it to?
To quote the great Vinnie Jones: "Now please, enlighten me."
