Do these velocities seem unrealistic?

[Jason_W]

I tried out my Chronograph for the first time today, but I'm not sure I'm getting accurate results.

For instance: .30-30 federal 150 gn factory rounds: Avg. velocity= 2460 Extreme high=2470 Extreme Low=2451

357 mag 158 gn Hornady XTP 17.0 gn lil'gun Avg.=1864 Low=1838 High=1881

.357 mag 180 gn Rem SJHP 15.0 lil'gun Avg.=1699 Low=1678 High=1716

The .357 was a marlin carbine and distance from the muzzle to the chrony was 12 feet (the maximum the cable to the monitor would allow)

The lighting conditions were variable today with the clouds periodically blocking the sun. Without the screens, things seemed way all over the place, so I put them on, which seemed to tighten the numbers up a bit. Still, there is about a 50 fps difference between some of the high and low figures. Keep in mind that when I handload, I weigh each individual charge.

Thoughts?

[Terry Murbach]

LOOKS FINE TO ME. WHAT YOU DO NOT UNDERSTAND YET IS YOUR CHRONOGRAPH WILL ASK YOU MORE QUESTIONS THAT IT WILL ANSWER. THIS WAS YOUR FIRST ONE.

[Hobie]

LOOKS FINE TO ME. WHAT YOU DO NOT UNDERSTAND YET IS YOUR CHRONOGRAPH WILL ASK YOU MORE QUESTIONS THAT IT WILL ANSWER. THIS WAS YOUR FIRST ONE.

There is the answer!

I don't know the barrel length on that .30-30 but everything is within reason (as Terry noted). I know that when I got first got my first chronograph I was amazed by the velocities of some loads and disappointed in the velocities of some other loads. I was also astounded by the consistency of some rather hastily assembled loads and the lack of same by some carefully crafted cartridges. You should have a lot of real fun now.

[Jason_W]

Remington factory 125 grain soft points were breaking 2100 fps

[Bramble]

No
velocities seem fine.

The 50 fps variation is well within that expected for this type of bulky powder and case design. It can be easily explained away by a small variation in internal case capacity of neck tension and is statisticaly insignificant.

[pharmseller]

I recently used my chronograph for the first time as well. Velocities were posted here:
http://www.levergunscommunity.com/viewt ... f=1&t=8792
The 30-30 seems a little high but within normal ranges.

Quinn

[Jason_W]

No
velocities seem fine.

The 50 fps variation is well within that expected for this type of bulky powder and case design. It can be easily explained away by a small variation in internal case capacity of neck tension and is statisticaly insignificant.

That's good to know.

I was just a little surprised.

I was expecting around 1500 fps for the 180 grain loads and maybe 1700 for the 158s.

[Old Savage]

I have recently chronographed Federal 150s in three Winchester 30-30s:

2350 fps in the 20" barrel
2407 fps in the 24" barrel
2467 fps in the 26" barrel

Those are averages.

No frame of reference in the other loads

[Hobie]

I would expect 18 gr. L'ilGun with the 158 gr. bullets in the .357 Mag to give you 2000 fps give or take a mite...

[Jason_W]

I would expect 18 gr. L'ilGun with the 158 gr. bullets in the .357 Mag to give you 2000 fps give or take a mite...

Knowing that, why did I buy a .35 remington

[Rusty]

I was going to post this as a PM but it just needs to be said out loud.

Praise the Lord for Terry. I really find it pleasant today to finally find someone I can count on to always put things in the proper perspective.

Good on the learning curve there Jason. I think if you care to look at some of Paco's data for the .35 Remington, you'll find that it can be handloaded to much better than factory velocities.

[Grizz]

My chronograph experience was similar.

There are lots of variables. I shot standing off hand. I'm sure I introduced lots of variables of bullet location going over the sensors.

I bet you should use a bench rest setup and a vice if possible to keep the bullets traveling as close to the same line as physically possible. Otherwise the relocation of the bullets shot to shot have the potential to change the perceptions by the chrono...

Grizz