FPS Question

[cherrypointmarine]

I have a 29-3 Silhouette which I've been enjoying at our 200yd range . I have some Georgia Arms 200gr "Deer Stoppers" rated at 1650fps . It's my understanding that they use a 6in barrel when taking their readings . How many more fps do you think I'm getting out of my 10 5/8 barrel ? I've been looking at a 629-5 12in Extreme Hunter , what kind of fps would one expect from the 12in barrel ? Is there a formula for figuring this out ?

 

[toad67]

Try this:
BBTI - Ballistics by the Inch :: .44 Mag Results

 

[Erich]

Playing with chronograph since the late Eighties has shown me that every gun and load make a law unto themselves. The site linked supra will give you something to think about, but if you want to know your load in your gun, run it over a chronograph.

 

[LVSteve]

Playing with chronograph since the late Eighties has shown me that every gun and load make a law unto themselves. The site linked supra will give you something to think about, but if you want to know your load in your gun, run it over a chronograph.

This, no question. There is a guy on youtube who does a lot of ammo tests in various calibers. After looking at many of them, I have reached the conclusion that his regular 9mm test gun has a 'fast' barrel, while his 45 ACP gun is 'slow'. Either that, or his chronograph has a peculiar ability to read 9mm higher than it should, something it does not do with 38 Special or 380 ACP.

 

[ImprovedModel56Fan]

Basically, what Erich said. The original velocity quotes are suspect, guns differ in several aspects, and the effect of barrel length varies with the powder used. I have observed all of the preceding even with my limited use of a chronograph.

Primarily because powders vary, no formula is universally or even commonly correct, and probably not even all that close.

 

[DWalt]

Typically each extra inch of barrel length will add around 20 ft/sec. But that is wildly variable. The Ballistics by the Inch website is about as accurate as you will find regarding barrel length vs. muzzle velocity.

 

[Alk8944]

Typically each extra inch of barrel length will add around 20 ft/sec. But that is wildly variable. The Ballistics by the Inch website is about as accurate as you will find regarding barrel length vs. muzzle velocity.

TRUE, BUT: It is rare that factory ammunition delivers the velocity advertised for it! It is not uncommon for ammunition for handguns to actually produce velocities 100 FPS or even greater less that advertised velocity, even in barrels the same length as the ammunition manufacturer may claim produced advertised velocity.

Unless you shoot your gun with the ammunition you are asking about over a chronograph you have no starting point upon which to begin estimating for varying barrel lengths!

 

[stansdds]

A chronograph is the only way to know for certain.

 

[Pisgah]

My only comment would be that the velocity is utterly irrelevant to whatever you are shooting at.

It's fast enough...

 

[Bald1]

Hmmmmm I think it’s relevant. A faster bullet shoots flatter and can increase accuracy. Especially when estimating distance. Increased velocity gives you a little room for error. Velocity contributes to energy levels as well.

 

[cherrypointmarine]

Thanks a lot for the input . Our range buddy with the chronograph has been down lately . I was just wondering if there was something akin to a wild a** guess theory out there somewhere .

But I do like Pisgah's answer though .It's fast enough rates up there with the best scientific theories .