More .357 Magnum testing

[Brick]

This time the Sierra 140 gr. JHP is the bullet set with a C.O.A.L. of 1.585". Added A#5 powder to the test loads because I have it on hand and it is included in the Sierra Manual Ed. 5, which is the source for this round of testing.
Practically everything else is the same. Including the feeling of confusion I get when I look at the results! I still find a few instances where heavier powder loads give lower velocities and some cases where the increase in velocity is very small for the increase in powder weight.

I got to thinking also if there's an established way to evaluate the "efficiency" of a powder at a given charge and bullet. For example 19.4grs of 296 gives 1277 fps (average) and the same weight of H110 yields 1228 fps. If I divide the velocity by charge weight I get 1277/19.4 = 65.8 fps/gr and 1228/19.4 = 63.3 fps/gr. Therefore I can judge that 296 is more efficient than H110 which seems to hold since it gives higher average velocities for all but one charge weight. If I toss in A3% at 10.6 gr. with a velocity of 1181 I get 1181/10.6 = 111.4 fps/gr. Outclassing both of them for this bullet. Unfortunately it hits its maximum at 10.8 grs.

Found a jug of Blue Dot at an LGS. With luck the weather will stay good enough so I can get one more round of tests in and go right to the carbine.

[gghbi]

Just a thought based in part on my black powder experience. Is is possible the higher velocity with the lower powder charges is because the larger charges are not fully combusting before the bullet leaves the barrel and a part of the explosion is wasted on muzzle blast/flash. If this is the case the results from the carbine with a longer barrel should be interesting.

[Brick]

^^^^! That's pretty much what I've been thinking! Consequently the loads I'm considering the most desirable for the carbine are not the heaviest, but those with a "better" SD and close to the top velocity.

[Delkal]

I got to thinking also if there's an established way to evaluate the "efficiency" of a powder at a given charge and bullet. For example 19.4grs of 296 gives 1277 fps (average) and the same weight of H110 yields 1228 fps. If I divide the velocity by charge weight I get 1277/19.4 = 65.8 fps/gr and 1228/19.4 = 63.3 fps/gr. Therefore I can judge that 296 is more efficient than H110 which seems to hold since it gives higher average velocities for all but one charge weight. If I toss in A3% at 10.6 gr. with a velocity of 1181 I get 1181/10.6 = 111.4 fps/gr. Outclassing both of them for this bullet. Unfortunately it hits its maximum at 10.8 grs.

All smokeless powders have the same amount of "energy" per grain. It is just that some release the energy faster (burn faster).

What makes a bullet move is the pressure x the time it is in the barrel. A fast powder like bullseye will ignite almost instantly so it will get to full pressure quickly. Unfortunately the pressure spike doesn't last that long. So you need a slower powder that keeps pushing the bullet out steadily. But going too slow gives you low pressure / erratic pressure and wasted powder. Every cartridge has a burning rate sweet spot. Looking at the reloading tables there is always one or two powders that give the highest velocity. Those are the ones that will fill the case to 100% and have the optimal burn rate.

H110 / W296 are EXACTLY the same powder. They were always made by the same company in bulk then rebranded. The velocity difference you see is just lot to lot variations. One of your lots is faster than the other. That is why they always say if you buy a new lot of a powder you are supposed to back off a little ande work your max up again.

Also H110 / W296 is on the slow side for a 357 (especially for a 140 grain bullet). Try HS-6.

[psweigle]

I shoot 158gr bullets from my ruger 77/357 with a stiff charge of h110 and a magnum primer. This combo works great in the coonan and all of my 6" revolvers. The carbine is quite a bit faster than the revolvers. What i found most interesting, is that the coonan is also noticeably faster than the revolvers. Im pretty sure this is due to the coonan, being a semi-auto, not having a cylinder gap.
The only other powder that ever got fantastic consistency for me in 357 magnum, is no longer made. Im sure glad I still have an 8lb jug of it. Good luck in your testing.

[Bang]

Guessing you are referring to HS-7. An equivalency chart says HS- 7: Blue Dot, W571, AA 9, and N350. Tried them? (I think Winchester 571 is out of production, too?)

[wanneroo]

I just finished priming a lot of 357 cases today, my first time reloading 357 Magnum so I read these threads.

I got one set of cases primed with regular S&B primers for Berry's 158g plated bullets with Unique and another set with magnum CCI primers for 158g Hornady XTPs and H110 powder.

[psweigle]

Guessing you are referring to HS-7. An equivalency chart says HS- 7: Blue Dot, W571, AA 9, and N350. Tried them? (I think Winchester 571 is out of production, too?)

Hs-7 & 571 are the same thing, and yes, thats what i was referring to. Great powder, too bad its not made anymore.

[Brick]

I just finished priming a lot of 357 cases today, my first time reloading 357 Magnum so I read these threads.

I got one set of cases primed with regular S&B primers for Berry's 158g plated bullets with Unique and another set with magnum CCI primers for 158g Hornady XTPs and H110 powder.

I've got another batch of 140 gr Sierra's loaded with Blue Dot ranging from 11.1 gr. to a near maximum of 13.6 grs. I'm hoping the Blue Dot tests well, I'd like to see less (much less) muzzle flash, good velocity and good standard deviation numbers too! Loading the stuff I found I like the bulky case filling flakes, in the future I might try it out for .38 Special also (the Sierra Manual has charge weights for it with 158 gr. bullets). I also like that the charges are lower in weight. With luck I'll be able to out tomorrow. I prefer testing when the air temperature is 40 and rising.

[abner13]

Blue Dot is my favorite sixgun powder , and it's good in short or long barrels. And good for mild to wild power levels. Unlike slower powders it does not need full to compressed loading density for maximum burn efficiency like H-110/W-296 or 2400 , etc.

I use 10grs with a 160gr hard cast Keith-SWC.