.308 Chrono Results = ?

[Wilburt]

So I chrono'ed 3 loads the other day.

DSA Arms SA58 16" Fal (.308 Win)
Mixed Brass
145 gr FMJBT (MilSurp)
Trimmed and Sized with X-Die ~3 Reloads (Read possible not all the same length)
Seated to 2.790"
Rem Large Rifle Primer
IMR Trailboss

Now I made 10 with:
10.0 grs (Avg 1172 FPS)
12.0 grs (Avg 1332 FPS)
14.0 grs (Avg 1217 FPS)

I really don't think I mixed them up. Is it plausible that the 12 gr could be faster than the 14 gr?

 

[JimKirk]

The only way to know for sure... redo the test!

 

[Wilburt]

I figured something like that, at least to know 100%. Logic would say I messed it up. However just wondering if anyone here has had something like my results. If it was possible.

 

[JimKirk]

If you'd really like to see...

Pick out 30 cases that are the same brand, I would weigh the cases and get them as close as I could to get 30 that have a standard weight, what ever weight that may be.

It probably would help to weigh out 30 bullets that are near the same...

Then run your test, making sure to keep them separate from each other, then you would have an even better idea.

I've done just such a test myself ... inquiring minds just want to know!

Jimmy K

 

[Mikee Loxxer]

That is a pretty weird load. Trail boss for pushing 145 gr FMJ bullets out the end of an FAL?

 

[azar]

I've had similar results a few times, usually due to a change in lighting conditions (i.e. sun had moved in the sky and was hitting the sensors directly instead of hitting the diffusers).

Best to redo to know for sure.

 

[JDGray]

Man...... That sure is a waste of a good rifle cartridge

 

[Wilburt]

I know. I've been playing with silencers recently. I don't want to shoot lead through 'em, so this is the slowest published data I can find. I know there is home grown loads but.... Point of impact at 150 yards is about 450 meters off. Using my ACOG the and holding at the 600 meter line verses the 150.

Hodgens website is where I got the data. I only know that due to THR!

 

[Zak Smith]

It is.. possible... but I agree more unlikely than likely.

I have seen inversions like that from time to time.

 

[Wilburt]

Thanks guys.

 

[ranger335v]

"I really don't think I mixed them up. Is it plausible that the 12 gr could be faster than the 14 gr?"

Yeah, it is easily possible. In a small sample like ten that could well happen with such light charges in a moderately large case. Vastly reduced charges in largish cases can produce some highly variable (but still quite safe) pressures, appearantly depending at least somewhat on the position of the powder before ignition.