Velocity Disparity

[Rummer]

I have noticed that when I chronograph handloads I typically get a velocity of 80-100 fps less than the published velocity for a given load.

This has been true regardless of barrel length.

In my .35 whelen,for example, I shoot 58.5gr of 4320 behind a 200gr Hornady SP.  The Hornady 3rd edition lists velocity for this load, in their 22 1/2" barrel, as 2700 fps.  10 shot strings run over my chrony average 2600.

In the same rifle Remington 250 grain factory ammo lists as 2400 fps but I only get 2300 fps over my chronograph.


Has anybody seen this before?
Could I be doing something wrong?

[butterman]

Every barrel has it's own pressure limits ,that is the reason you start your powder loads low and work up , at that load, their pressure produced that vel. your's is 100 fps. slower by your chrono, there are like 10 variables , 100 fps. can be normal .  I have a browning micro-medalion with a 20" barrel I allways are 150 fps. or more off published, Do'nt worry just look for pressure or change bullets and work up again if you have to have the extra 100 fps.

[Questor]

It could be a lot of things, none of which are terribly important. I could be the rifle. It could be the chronograph too. The ones most of us buy are relatively inexpensive and incorporate some level of error. They are not going to be as accurate as, say, a 3-screen Oehler.

One thing you can try is to see whether you are shooting at an angle. You need to shoot exactly parallel to the horizontal plane of the sky screens. Any variation from this will mean that the bullet is flying farther than the shortest distance between the screens and that will certainly affect readings.

[Siskiyou]

A year or so ago I did a lot of test firing of different reloads and factory ammunition in a Savage 110 and in a Remington 700, both in .270 Winchester Caliber.  The Savage barrel is approximately 30fps faster then the Remington barrel with 130, 140, and 150 grain loads.
Both barrels are 22-inches.  I thought about buying a 24-inch barrel for the Remington, then common sense told me to stop.  The 22-inch barrel is accurate and it has proved itself on game. 

[Catfish]

I have never got the velosity that the manual says. I have gotten both higher and lower readings though. You must also rember than not only does it vary from barrel to barrel but the temp. and berometer will also change the velosity from the same barrel.