Load Testing: IMR 7625 powder

[Radom]

Here is some more load data...  The updates were done with 10 shots each.  I like the 135s enough that I loaded up 400 of them for tomorrow, but I may get rained out.   

That's very interesting.  The Walther demonstrates the "behavior" I always associate with this powder (SD decreases as charge increases), while the CZ does not.  Granted, we're looking at small sample size (not a criticism), but I still find it interesting.  Both IMR SR-7625 and SR-4756 have always shown a predictable geometric progression in my testing. 

I have a lot of raw data, but I would need to input it in Excel to verify.  This is the only free time I've had since tax season ended, so expect it sometime after I come back from vacation in early June.  I don't think I could force myself to work with a spreadsheet in the name of "fun" for at least a month.  I should have been a teacher, they get the entire summer off without front-loading the insane hours!

[Wobbly]

Equipment
Caliber:    10mmAuto
Bullets:    RMR 180gr plated RNFP
Brass:      StarLine (new)
Primer:    Winchester Large Pistol WLP
OAL:        1.250"
Pistol:      Dan Wesson 10mm Pointman (5" 1911)
Qty:        8 rounds each, slow fired
Weather:  40F and highly overcast
Chrono:   ProChrono DLX

Powder:   7625  (6.3-7.0gr)
Max Velocity:  1200 fps


Load      Avg Vel           SD
6.6gr            954              26
6.7               979              24


NOTES
• Meters great
• Smooth response, typical of other single-base powders
• These loads were too low, and need more testing


 

[Wobbly]

Don't know if anyone is still shooting 7625, but I've been loving it in 38 Special. No chrono data, but 4.1 works great with 148gr coated lead DEWC, like MBC and ACME. 4.3gr seems to be best with plated Berry 148gr DEWC.

These are flush seated, or at the first cannelure exposing about 0.10".


Berry with flush seating


Alternate loading for MBC with crimp cannelure

[painter]

What are you going to replace it with when your supply is used up? 7625 is discontinued.

[Wobbly]

Probably have to go full-on N320 and N330. But since I got an 8lb can, which I only use for pistol, that decision won't need to made until I'm 95 or so.

[painter]

Probably have to go full-on N320 and N330. But since I got an 8lb can, which I only use for pistol, that decision won't need to made until I'm 95 or so.

The shotgun guys really miss that powder.

[Wobbly]

Right when 7625 became hard to get I noticed that there were two 8lb jugs at my Club's supply depot. I bought both and sold the other to a friend at work. We've both since retired. Now I feel like calling him and asking what became of that jug.

[Radom]

Right when 7625 became hard to get I noticed that there were two 8lb jugs at my Club's supply depot. I bought both and sold the other to a friend at work. We've both since retired. Now I feel like calling him and asking what became of that jug.

Believe it or not, I still have a few of the old 8 oz. "cans."  As you well know, I love me some 4756, but I was never too crazy about 7625.  The way things are now, I suppose I will have to load some lead and that 7625 if I want to shoot my 10mm anytime soon...

In all seriousness, IMR SR-7625 is very versatile for its burning rate.  The only problem is that niche is sort of small...

[Wobbly]

The only problem is that niche is sort of small...

Thus, 4756 !! 

[Radom]

The only problem is that niche is sort of small...

Thus, 4756 !! 

PREACH IT, BROTHER!!!

[Radom]

In all seriousness, you may want to consult older manuals and sources when dealing with older lots of powders.  "Cans" of IMR powders are getting a little bit old, by now.  I don't mean that they are expiring (unless they smell bad), but they do benefit from older load data.  In the handgun realm, I wouldn't try to "reinvent the wheel" by loading them with plated bullets, or other new designs.  Stick with the bullet weights/types that were available from 1970-2005.  I wouldn't waste any currently unavailable powder on plated bullets, FWIW. 

[Wobbly]

"Cans" of IMR powders are getting a little bit old, by now.  I don't mean that they are expiring (unless they smell bad), but they do benefit from older load data.

90% of the bad smell is the nitric acid coming out of solution. Since 7625 and 4756 are single-base powders they have no nitroglycerine to break down.