Strange (low) velocity readings while starting Ladder

[Alan Griffith]

You may have just viewed my post on a Ladder test I shot yesterday using Ramshot Hunter in my 30-06 and Nosler 180 Ballistic Tips.

Once I was done with the Hunter Ladder I started on a Reloader 22 Ladder using the same bullet. I start with 5 fouling shots from 58 to 61 grains. I know this particular rifle pretty intimately (much to my wife's chagrin [img]/ubbthreads/images/graemlins/grin.gif[/img]) and have always been able to exceed book max prop charges. Not feeling too greedy I had only preloaded 1 round at 61 grains (60 is book max).

1. 58.0 gr = 2541 fps, .0001 expansion
2. 59.0 gr = 2590 fps, .0000 expansion
3. 60.0 gr = 2638 fps, .0000 expansion
4. 60.5 gr = 2649 fps, .0000 expansion
5. 61.0 gr = 2675 fps, .0000 expansion

I measure case head expansion just forward of the extractor groove with a .0001" mic and stop when I hit .0006".

Having run out of fouling/pressure rounds and wanting more velocity than 2675 (especially from Rel 22) I did not want to stop thier. I pulled out my Harrell's powder meter and began to single load upto 63.5 grains.

Here's the interesting point.

61.4 gr = 2639 fps, .0002" expansion
62.5 gr = 2662 fps, .0002" expansion
63.0 gr = 1418 fps, 0 expansion
63.0 gr = 1418 fps, 0 expansion
63.5 gr = 1412 fps, 0 expansion

Here is my guess. The WLR primer did not have enought "umph" to ignite that much powder in an '06 case.

Any opinions?

Big Al

[dakor]

Are you sure you did not have a low battery in your chronograph? Maybe your graph went a little crazy on you did you shoot anything else through it?

[Alan Griffith]

Dakor,

It could be a possiblity, I suppose. The chrono was running great the whole morning with nary a single bad reading. I'd have to check my owners manual but I believe the read out would indicate a low battery.

The one thing which makes me believe the total prop charge was not burning completly was the lack of case head expansion, zero, naughty!

Big Al

[Fiftydriver]

Could you tell a difference in recoil? It would be dramatic dropping from nearly 2700 fps down to 1400 fps. It would be easy to tell from felt recoil alone if you were actually getting these velocities.

Kirby Allen(50)

[jb1000br]

What chrony?

the folding ones im guessing...

Also, how far away from the muzzle?

I ran my shooting chrony in front of my oehler 35 last weekend...SC gave results from 1600fps-3400fps IIRC, while actual velocity was between 2800-3000

the 3400fps was most likely muzzle blast thru the screens (even at 10 feet...cause it happened before and was around 3400fps), but the low reading made no sense, and WAS NOT REAL -- evidenced by the impact where it was supposed to at 300yds.

JB

[Alan Griffith]

Kirby,

Now that I think of it, the recoil was less.

Big Al

[Alan Griffith]

JB,

Ohler M33, 5 foot spacing, 10 feet from muzzle, sky screens in place with light overcast.

Big Al