# FPS Differences



## saskcoyote (Dec 30, 2006)

I've spent quite a bit of time shooting various calibers-powder-bullet combinations this summer. I'm puzzled by the results I'm getting with my .17 Remington. The speeds I get off the chrony are much different than the speeds listed in my loading manuals.

Here are a couple examples using 30 grain Bergers and H4895 powder out of Remington cases, Winchester Small Rifle primers, a 24-inch barrel and a bolt action.

The data I got directly from Berger Ltd. shows a 30 grain with 19.0 grains of H4895 at 3365 feet per second. A 30 grain with a max load of 21.3 grains has fps of 3728 according to Berger. My chrony loads give me an average of 3408 using 21 grains of H4895. As you can see the difference between Berger's 19 grains of H4895 and my 21 grains of H4895 is only 43 fps. The two extra grains in my loads should provide a much greater difference in my opinion.

Here's another 30 grain Berger load. Using 21.2 grains of 748 I'm averaging 3027 while a 22.2 grain load of 748 gives me 3314 fps. The Berger data has a 20 grain load of 748 at 3493 while a 22.2 grain load is 3856 fps. As you can see my 748 load of 22.2 grains and Berger's load of 22.2 grains has a difference of 542 fps.

Berger indicates it's using a 24-inch barrel for its test firing same as me, and because there appear to be few or no choices in brass, I'm assuming they're using the Remington brass same as me also. The only difference could be the primers. I'm seating my reloads for OAL at 2.15 inches, same as Berger.

I'd wonder about my chrony but the readings its gives me for other calibers are very near the readings I get from other reloading manuals using different weights of different powders.

The examples I gave you were for 30 grain Bergers and H4895. I got similar discrepancies using a number of different powders and similar discrepancies when I tested 25 grain Bergers.

So what gives that there would be such fps discrepancies between my reloads and a manufacturer's reloads in the .17?

Good luck and shoot straight. Saskcoyote


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## People (Jan 17, 2005)

Not all tubes are equal. Some are fast and some are slow. Then you have the real odd ones. I have a three grove Lilja on my 300WM and I am getting 3,000fps at 15feet. The books state my gun should be in parts at those speeds. My 7mmstw 81gr is a max load but some books show 84gr as a max load. It is faster than a 7mm Rem Mag but not as fast as those in the book. Even for 81gr.

What was going through the minds of all of Chuck Norris' victims before they died? His shoe.


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## xdeano (Jan 14, 2005)

Powder lots very from lot to lot. So do primers. Case capacity is also inconsistent. Temperature could also play a part or feet above sea level. The reloading book it good to get your starting capacity. The rest i ignore. Ill get.the velocities i get. I watch my pressures and more importantly my accuracy. If im shooting over a chronograph im also paying attention to what my average velocity is compaired to my es and sd's. I really wouldnt worry about book values. They're lawyer proof anybow. 
Xdeano


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## specialpatrolgroup (Jan 16, 2009)

I have yet to get a chronograph, velocity would be nice to know for creating ballistic tables that were spot on, but shooting can also tell you that.


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