I just got back from the range having loaded up some 38 spl & 357 mag rounds for the first time with IMR 4756.

In both calibers, I had a LOT of unburned powder. I mean tons. Having never used 4756 before I'm not sure if this is normal.

Now, the loads I used were not max, but not super light either according to the manuals.

Both calibers were loaded with 158 gr lead bullets and CCI regular small pistol primers.

38 spl was loaded with 5.0 grains of IMR 4756 and the 357 mag was loaded with 6.0 grains of IMR 4756.

Are these loads way too light causing the unburned powder? Should the unburned powder "burn better" with heavier loads? I don't want to use the old #8 Speer loads because I like my fingers. I referred to a IMR loading manual only a few years old (2003?) that had max loads of 5.4 grains for the 38 spl and 7.7 grains for the 357 mag. So figure my loads of 5 and 6 grains respectively aren't THAT light.

Is it normal for IMR 4756 to leave a LOT of unburned powder?

I know a lot of you guys like 4756, so maybe the expets can chime in.

Thanks guys.

I have used SR4756 in the .38 Special but only full throttle loads, so I'd say your charge is very light. And no, I have not noticed any unburned powder with the standard Federal primer.

Dave Sinko

aalmcc4,

Un-burned, or correctly partially burned powder grains indicate nothing more that the particular propellant is loaded below it's balance point, the pressure where it burns most efficiently. I can't tell you what this pressure is for SR 4756, just that it is well above the 15-16,000 PSI standard for .38 Special. In short, don't worry about it. Most powders will leave partially burned grains at .38 Special pressures.

Notwithstanding the Speer Manual #8, which I am glad you recognize as having a problem with 4756, your loads are not light by any standard. My standard for data has always been the powder manufacturer because they are in the best position to properly pressure test their product which is absolutely necessary to properly blend canister grade reloading propellants. You apparently checked a relatively recent IMR Manual and found 5.4 gr as maximum for .38 Spl with 158 Lead SWC. My 4/1998 IMR list shows 5.2 gr as maximum, and the current data from Hodgdon, distributor of IMR branded powders, shows 5.3. All are in the same ballpark. Your load is not "light" by any stretch.

Not that neither IMR or Hodgdon shows a +P load for this bullet in .38 Spl for some reason. If you want a +P level load you can increase the listed charges by 8% to achieve pressures in the 17-18,000 +P range. That is 5.6-5.8 gr.

If you want less partially burned powder change propellants, but 4756 is excellent for standard pressure revolver cartridges such as .38 Spl, .44 Spl, and many others. It isn't a good choice if you want Magnum performance from the .357 or .44 Magnums.

I recall we had this discussion before. SR4756 will burn clean under 158 gr. bullet if the charge is over 6.0 gr. Lower charges are often dirty.

Mike

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9x19, 9x29R, 9x33R, 10x22

Using current data with SR4756 is going to be exceptionally frustrating. Velocities are not going to be anywhere near published data.

The funny thing is, their pressure data is nowhere near top for each caliber either. Look at the 357Mag data from the Hodgdon website. 6.5gr with a 158gr LSWC is supposed to develop 1200+fps with 27,000psi.

Now, SAAMI maximum pressure is 35,000psi. Something is awry here.

I can tell you this, if you use that data, you are not going to get anywhere near that velocity. Sure, their barrel was longer than most, 10" but still....................

I use older data and have had no problem with SR4756 and unburnt powder. All of mine burns!

It is my powder of choice in 40S&W too. (for now)

Personally, if you look at the lead bullet data on the Hodgdon website, they are using something other than pressure as a limiting factor. Personally, I think they are using velocity. Somewhere around 1100fps or something.

They aren't afraid to push the pressure up on some of the "new darlings" of their marketing scheme. Check out AutoComp and jacketed data.

No, I have had no unburnt powder with SR4756 when it is loaded at older data levels. I have had horrible results with it using current data.

I've been using SR 4756 since 1973 and have never had a problem with it, unless I use Starline brass in .360 DW or .357 Max. I use Speer #8 data exclusively with all .357 loads and many .38 Special loads and I still have all of my fingers.

'Course, what Paul ain't telling us is that he is missing both thumbs!

Just kidding!

Thats better than me, I have two left thumbs, and am right handed.

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dd884
JMHO-YMMV

Maybe I should have said I still have all of my phalanges?

The published SR 4756 loads I use have exhibited less pressure signs than published Blue Dot loads. That being the case, last night, I loaded the exact load I used in 1973, including the Sierra 125 gr JHC.

I've worked up to the Speer #8 loads with 158 gr. LSWC bullets but I don't have all my fingers. I lost the tip of my left index finger in an industrial mishap. No worries though, I'm fine unless I have to count higher than 9 7/8

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Andy

Too funny! hahahahahaha!

Sorry for your loss though!