Blue Dot?

[Cheapo]

Just read Duplex loads, the second thread.

I know y'all are gonna ARRRGGGHHH!!!, but I gotta ask:

Isn't Blue Dot a blended powder?

Personally, I wouldn't even experiment with that stuff without at least a strain gage mounted on both a minimum-chamber rifle, and another on a max-chamber rifle. And I'd test at all sorts of temperatures!

Perhaps using the BP model, a fast "boost" could convert heavy-bullet .223 loads with slow powders into performers with useful velocities? Derrick Martin reports that you can't get enough powder of one lot of "slow" surplus powder into the case, to get any useful velocity... Seems to me that layered and compressed would be safer than blended.

 

[Keith J]

BD is a double-based powder with the little ID flakes coated with a blue dyestuff instead of graphite. Nothing "blended" about it as the graphite coating only slightly deters the burning rate. Its primary purpose is an anti-stick.

I doubt any benefits can be had by using a "booster" of faster powder since its burn rate would accelerate the remaining slower charge. Peak pressure in most rounds happens before the bullet has traveled 1/2 way down a normal barrel.

With duplex, you introduce TWO more variables into the load matrix, those being weight of A and weight of B. Unless you have a real-time interior ballistic recorder, using velocity to determine the product of two variables is sketchy at best. This is the old one equation and two unknowns problem.