No CG needed

[MotelAlpha]

At what velocity do you need GCs for hard cast boolits?. I cast and shoot both a 577 and 600 NE for my double rifles. I drop cast them into very cold water, and have not had "much leading". I will use my chrono as soon to see actual velocity. I load at approx 3/4 of full load.

[MBTcustom]

You should be able to get 'em up to 1400 at least, with no problem. Do some fancy footwork, and it is possible to drive a PB boolit to almost 2000FPS.
If you lead the barrel, it's not a problem though, don't be afraid.

[wool1]

A 600 NE full load I think is around 1900-2000. Seems you should have some room to work before a plain base would be a problem. Maybe experiment with different lubes also. I think in a 900 grain projectile, it would be all anyone would want to shoot. The 600 might be a straight enough walled case to invert a gas check. Someone more qualified might want to verify, but it should work.

[MotelAlpha]

A 600 NE full load I think is around 1900-2000. Seems you should have some room to work before a plain base would be a problem. Maybe experiment with different lubes also. I think in a 900 grain projectile, it would be all anyone would want to shoot. The 600 might be a straight enough walled case to invert a gas check. Someone more qualified might want to verify, but it should work.
Thanks guys, So far I can get everything out. My guess is that I have exceeded the 1400 fps but by how much I don't know until I Chrono. I chosed not to routinely load the 900 grain it is just toooo much overall recoil even in my 14 lb DR. At over 70 grains of 3031, or 64 grains of varget, it will stop most anything for sure.....As I have read on your forums, the big flat pointed boolits penetrate just fine.I only cast a 600 grain so far, and probably won't shoot anything larger as both guns will only be used in the States.

[DrBill33]

How hard are your bullets? In my .50, I reach 2050, using a BHN of 19 and GC'c

[missionary5155]

Good morning
Howdy MotelAlpha and welcome to our little place !
That all sounds like fun ! My big bore double thumper is a simple Fox 12 guage I shoot Round ball out of. In a less than 9 pound double a 465 grain RB at 1550 fps is plenty of excitement for my little body to absorb.
But your issue is all about pressure. When the pressure overcomes the capacity of your mix to support that pressure then is when you will need a GC. I find boolit recovery and "reading the boolit base" to help alot understanding what is happening in the barrel.
I have used cereal box "GasChecks" when it seemed some boolits were getting to that threshhold of pressure failure. Then you can also cut sheet copper and soda can aluminum for the same effect but far longer able to withstand hot gasses. Glue them on with a smear of Super Glue or even a smear of lube. Straight wall cases work very well with this.
You can also go to a slower burning powder and reduce the pressure curve. Going to a slower powder around the burn speed of 4895 will quit possibly negate the need to use a base protector.
But that is the fun of making our own ammo. All the different possibilities... never ending avenues to traverse and investigate.
Mike in Peru