Interesting finding on velocity difference between 158 grain Zero bullets.

[Nevada Ed]

Looking at that picture of the two bullets, makes me think that
they are close enough to not make that big a deal out of fps
if the same identical components were used.
However you did say mixed brass.......right ?

One thing about the fps, though.
It does seem a little low to me since 14.5 grs of 2400 with a 158 XTP.......
out of my 686 6" and a cci primer does 1274fps with R-P cases.

 

[rwsmith]

Thanks.....

Looking at that picture of the two bullets, makes me think that
they are close enough to not make that big a deal out of fps
if the same identical components were used.
However you did say mixed brass.......right ?

One thing about the fps, though.
It does seem a little low to me since 14.5 grs of 2400 with a 158 XTP.......
out of my 686 6" and a cci primer does 1274fps with R-P cases.

Thanks for confirming that. I was really scratching my head. Now does anybody have an explanation as to why the velocities seem low??? I didn't quite understand the distance between the muzzle and chrono. How far was is??? I'm starting to think that the chrono might be hinky.

 

[GB]

I can't speak to much of the OP's test. Except it sounds like a good day at the range! But I can speak to the "dirty" 2400. I have been shooting 2400 since the mid 1960s. With loads that were Phiffle to more powder than most sane people would shoot. From 38 spc. to 44 mag to reduced rifle cast loads and I have never been able to not have powder(or as I like to call it---Gravel) left on and in the gun and surrounding area. Once, after shooting several hundred 38/357 loaded with 2400 on a concrete shooting area, it was necessary to sweep the area in front of my shooting spot because it was like someone had sanded that area and it was slippery. Sort of like walking on marbles or small ball bearings.

 

[fredj338]

Did you weigh the bullets before loading them to verify that they were both the same weight?

Just because they are both in the 158 grain class doesn't mean they both weighed exactly 158.0 grains and if one type was even a couple grains heavier than the other, that would be sufficient to explain the difference.

Not likely. Measure the actual bearing surface, has far more affect than even oal.
I just ran some liars using bayou 145gr RN 9mm. My std competition bullet is a 146gr RN. The bayou has no lube groove, solid shank. I get the same vel as the heavier bullet, both Hi-tell costed, same oal, but the bayou takes 3/10gr less powder to get there. The solid shank s offer far more bearing surface, higher vel.

 

[forestswin]

.......... I didn't quite understand the distance between the muzzle and chrono. How far was is??? I'm starting to think that the chrono might be hinky.

Rw
My chronolograph instructions state to set the 'chrono' from 5 feet to 10 feet from muzzle for pistols......10 to 15 for rifles
This is to eliminate muzzle blast from interfering with the readings.

The OP realized that could have been an issue and moved the 'chrono' out more.

 

[muddocktor]

I asked it above but I think it was blown out of the water by the bearing length theory.

"Aren't all of those velocities low for that load???? 14.5 grains of 2400 with a 158 gr jacketed should be going about 1200 ft/sec or better???"

RW, I addressed your question in post #14, below the pics of the bullets. According to Alliant's online data, a max charge of 14.8 grains of 2400 with them using the Speer 158 grain GDHP bullet is good for 1265 fps velocity. But they are using a 10" test barrel. And they don't specify which gun they are testing with, so we don't know if it is a revolver or a non-vented test setup. My 627 Pro has a 4" barrel and you know that a shorter barrel such as that will lose quite a bit of velocity as compared to a 10" barrel. And that is especially true when you get to the slower magnum powders such as 2400 or H110. When shooting these, I was seeing quite a nice ring of fire coming out of the barrel at times, indicating to me that as the bullet was exiting the barrel I still had some powder combustion going on.

And forestswin is exactly right why I had to move the chrono out some. I was getting interference from the unburned combustion products leaving the barrel with the 2400 loads from my 627. The 9MM and the 629 I also shot that day had not given me any problems at the same distance to the chrono, but I was using faster powder in those loads and they weren't kicking out unburned powder and/or carbon like the 2400 loads were. 2400 reminds me a lot of IMR4227 in the way it burns dirty and leaves unburned powder and stuff around the bench.

 

[rwsmith]

forest and mud...

Thanks for clearing me up. That would explain it, so back to the original question.

 

[forestswin]

Aren't all of those velocities low for that load???? 14.5 grains of 2400 with a 158 gr jacketed should be going about 1200 ft/sec or better???

rw
this is the original question? correct?
Speer #8 has data using a S&W Model 27 6 inch
and for 2.5" barreled Colt and S&W's

the bullet used for both are their 160 gr. soft point - it has a different shape than OP's bullet - but its of use in a comparison using the exact same bullet for both of their tests

6 inch data
15 grains / 1280 fps
14 grains / 1204 fps
CCI 550 magnum primers were used

2.5 inch barrel
15 grains / 1199 fps
also used CCI 550 magnum primers

from my experience....magnum primers add 50 fps in my 6 inch 686

so subtracting 50 fps
6 inch
15 grains / 1230 fps
14 grains / 1154 fps

2.5" barrel
15 grains / 1149 fps

OP used 14.5 grains and a 4 inch barrel

1037 and 1114 are a little low but
It seems to me his velocities are in the ballpark with the manuals, and considering the manuals are usually optimistic.