Differences between published velocity and your velocity (.357)

[LaneP]

I know these anomalies pop up from time to time but this one surprised me a little. The Alliant site shows 14.8 gr 2400 pushing a .357" 158 gr GDHP to 1265 fps from a 10" bbl.



Today I was able to take advantage of the unusually mild weather here in the northeast and ran some 2400 through my 7" bbl 686. My components consisted of Starline brass, CCI 500 primer, and a 158 gr Remington JHP over 14 gr 2400 (purchased 2018).

When I was deciding what charge weight to start with, it seemed like the Alliant velocity was a little low for a 10" bbl. Deciding on a charge weight, I did a little more research across the net and settled on 14 grains.

Velocity from my Competition Electronics chrono set at 12' from the muzzle measured 1422 fps for 6 shots. Extraction was effortless, no pressure signs and they were clean burning.

I know there are variables based on bullet construction and hardness, bearing length, case volume, interior gun dimensions, ect, but I still find that large of a difference odd, especially when they quote a 10" barrel and .8 gr more charge weight.

Anyway, such is life in reloading. Have a great day all.

 

[Ru4real]

I agree, that published velocity seems low. Misprint? Someone with a paper table could check.

 

[tightgroup tiger]

Alliant's data looks light to me to, but 1422 fps for 14.gr of 2400 out of a 6" barrel sounds a little optimistic to me also. I'm not saying it isn't do-able, just sounds a little fast. You may have a fast barrel on that 686.

 

[fxvr5]

The 10" is probably wrong.

That same data - charge weight and velocity - is from Speer's load manual (page 898 of #14), but they used a S&W Model 19 with a 6" barrel.
https://reloading-data.speer-ammo.c...caliber_357-358_dia/357_Magnum_158_TMJ_FN.pdf

 

[bangbig]

Yeah, I'm showing 1220 and 1300 depending on which bullet mfg. for 14g with 158g from my 6" 686.
Magnum primer.

 

[Walkalong]

Magic (fast) barrel, my guns are pretty close to that published data.

 

[Walkalong]

The 10" is probably wrong.

That same data - charge weight and velocity - is from Speer's load manual (page 898 of #14), but they used a S&W Model 19 with a 6" barrel.
https://reloading-data.speer-ammo.c...caliber_357-358_dia/357_Magnum_158_TMJ_FN.pdf

Agreed. 14.5 Grs 2400 runs 158s around 1200/1250 in my 4" & 6" barrels, and my 4" 586 is faster than my 6" Trooper.

 

[LaneP]

Thanks all for your insights and thoughts. I didn't mention in the original post but this is a brand new 7" rebarrel that I only recently received back from the S&W Performance Center. It was 4" in its former life. Definitely pleased with the performance of longer barrel .357 loads.

 

[enine]

I have some using Accurate #9 from their http://www.accuratepowder.com/wp-content/uploads/2018/11/WPHandloading-Guide-7.0-Web-REV.pdf page 26, Harnady XTP 158g max load 13.8g velocity 1367fps.
My 6 shot chrono test resulted in an average of 1364.17fps
I think I'd have to try pretty hard to get any closer.

Looks like they have a v8 now www.ramshot.com/wp-content/uploads/2020/08/WesternPowdersHandloadingGuide8.0_WEB.pdf
Same data on page 30

 

[fxvr5]

I have some using Accurate #9 from their http://www.accuratepowder.com/wp-content/uploads/2018/11/WPHandloading-Guide-7.0-Web-REV.pdf page 26, Harnady XTP 158g max load 13.8g velocity 1367fps.
My 6 shot chrono test resulted in an average of 1364.17fps

What gun and barrel length are you using? Thanks.

 

[enine]

Ruger Blackhawk 6.5" barrel.

 

[243winxb]

Vented VS test barrel velocity.View attachment 966268

 

[rfwobbly]

Don't guess. Call Alliant for clarification of their data.

 

[buck460XVR]

IME, 1422fps from 14 gr of 2400 under a 158 grainer seems pretty high.