.357 Load Faster Than Expected...(?)

[Kevin_G]

A while back I worked up an accurate load in my GP100 (4in. stainless). Started at the min and worked up (Sierra load manual). Here it is:

14.6 gr 2400
Sierra 158 gr. JHC
Rem cases (factory once fired)
Fed200 (small pistol magnum) primers
Positive Crimp, but not real heavy

The max load for this combination of bullet/powder in the Sierra manual is 15.0 gr (est vel 1250). So I finally got a Chrony and found that my load (14.6) is pushing the 158 gr bullet 1300 fps (avg) with an Sd of 17. Temp. outside was around 35-40F.

So here are my questions:
1) The Sierra manual uses CCI550 primers...should this alone make that much difference in Velocity?
2) Has there been a reformulation in 2400 that may not be captured in the Sierra manual (5th addition)?
3) The Speer manual velocities are roughly the same as the Sierra manual but without using magnum primers. Also, I read somewhere that magnum primers shouldn't be used with 2400. Any truth to this?

Thanks much!

 

[Virginian]

If you are using Unique, why do you care about 2400? Any component change can affect the result. I do not use magnum primers with 2400, but I do not remember why. Seriously. As to formulation changes, I don't believe it. More like lawyer changes. I am still using load tables from 1979 era Hercules manuals. I saved powder mauals for years, and it seemed like every two years the load data dropped. Your results may vary. Always approach any max charge with care.

 

[Kevin_G]

If you are using Unique, why do you care about 2400?

Typo...fixed in original post. Only talking 2400 here. BTW, if I'd used 14.6 gr of Unique...well, it would't be good. Thanks for the reply.

 

[fecmech]

Kevin--It looks to me like your in the ballpark with the manual. You are only 50fps off their reading and .4 of 2400 isn't going to drop velocity very much. I have two 6" revolvers that consistantly show a 40-60 fps difference with the same loads. I can go from a Federal to a Winchester case with the same load cutting the extream spread in half and raise the velocity almost 50 fps. I don't know how many shots were in your string for the 17 sd but if it was 10-15 the load appears fairly uniform. I would'nt worry about it.

 

[Kevin_G]

Thanks much for the reply...I won't sweat it then (15 shots in the string). I just thought since the velocity I was getting was roughly 70 fps higher than expected, and the spread between min & max load (Sierra manual) is only 50 fps, then maybe there is something going on here that I'm not accounting for. I'm not worried about the gun shooting 1300 fps, just curious. Thanks again...

 

[grendelbane]

I agree. This sounds like a pretty warm load, but if you worked up to it, and have no problems, it should be fine.

Loading manuals are guides. They give you guidelines to be safe. Due to the differences in components and individual guns, any velocities listed will be only approximate.

I have used many loads similar to yours. I don't have my notebook handy, but I think that my 6" Ruger usually did right around 1275 with a very similar load.

 

[Steve C]

1) The Sierra manual uses CCI550 primers...should this alone make that much difference in Velocity?

For sure, magnum primers most definitely push the pressure up with 2400.

2) Has there been a reformulation in 2400 that may not be captured in the Sierra manual (5th addition)?

No, its the same as it always was.

3) The Speer manual velocities are roughly the same as the Sierra manual but without using magnum primers. Also, I read somewhere that magnum primers shouldn't be used with 2400. Any truth to this?

Speer #13 makes specific reference to using standard primers only with 2400 and Viht. N110 as you get better performance and high pressures will result with magnum primers. (next to the last paragraph on pg 526.

I chrono'd an average velocity of 1,243 fps from my 4" S&W M66 using CCI 500 small pistol primers (standard) and 14.0grs ow 2400 behind a Remington JSP but on a much warmer day.

 

[ArchAngelCD]

If you are worried about the increased velocity over what your manual is telling you make sure your scale is correct and you aren't overcharging. Also, are you seating the bullet deeper than they did in the manual? That would increase the pressure, and in turn the velocity too.

 

[birdbustr]

I load 14gr of 2400 with 158gr Hornady HP/XTP with CCI magnum handgun primers and I get 1310 +/- 15fps out of my S&W 66 4" barrel. What you are getting sounds in line with what I would expect. Manuals FPS are just a general expectation of what you should get. Getting a chrony really does open up your eyes to your real bullet performance. I wouldn't reload without one now.

 

[Kevin_G]

For sure, magnum primers most definitely push the pressure up with 2400.

Yes...I was comparing the CCI550 primers used in the book with the FED200 primers I used...just wondering if there is a major difference between magnum primer brands. On another note, I did an experiment with a much lighter load keeping all things equal except the primers (FED100 or FED200) and was surprised to see that the magnum primers only boosted velocity 20-30 fps.

Your results with standard small pistol primers and 14.0 gr 2400 seem to be closer, on scale, with the results I got. I think the velocity #'s in the Sierra manual are low.

If you are worried about the increased velocity over what your manual is telling you make sure your scale is correct and you aren't overcharging.

ArchAngel...I've been concerned about that. I have an RCBS digital scale and weigh every charge...but just about every time I empty the pan and set it back on the scale it shows -.1 or -.2 and I have to zero it out...probably time to get some small weights and check the scale.

Getting a chrony really does open up your eyes to your real bullet performance. I wouldn't reload without one now.

Man I agree! Adds a whole new dimension of fun and learning...