Book vs. Real World

D21ALASKA

Beginner
Oct 29, 2013
171
23
How often do you fine folks find that the book data matches up pretty close to what you're seeing in the real world with respect to load/fps?
Personally I hardly ever see correlation between the two. Case in point I'm currently working a ladder for a new 338WM. I'm currently 1 grain below max book, 75, and showing over 100fps slower than min book at 72.
Not sure if my chrono, Magnetospeed, is off or what but this isn't the first time I've had this.
 

Guy Miner

Master Loader
Apr 6, 2006
16,462
718
Most of the time I find that the reloading manuals and what I get on my own chronograph are pretty close.

Regards, Guy
 

DrMike

Ballistician
Nov 8, 2006
34,807
952
If I approximate the conditions employed to generate the data in the reloading books, my results are exceptionally close. It is all the minor differences that add up to ensure that there is always room to make up.
 

D21ALASKA

Beginner
Oct 29, 2013
171
23
Thanks guys. Right at 200fps slower than book at the moment with 76gr of RL19 behind some 210 Partitions. Technically a compressed load but with the long tube drop funnel I've still got some room to play with. I've got some experience with lot to lot differences in the Alliant powders so maybe I just got a cold one. We'll see how she goes accuracy wise and maybe change it up a bit if needed. Have a bunch of 17 and IMR4350 on hand as well.
 

TackDriver284

Handloader
Feb 13, 2016
1,655
231
I get pretty close to book velocity, sometimes I don't, reasons are case volume, bullet seated out long to touch the rifling will reduce speed. I just start off .005" off the lands, and work up slow. I once had to go almost 4 grains more than book max to get similar book velocity for my 7 Mag. Sometimes I end up using a grain less powder and get max book speeds but I prefer accuracy over speed.
 

Hadsdad

Beginner
Jan 18, 2022
2
1
I do a lot of reloading for old military cartridges and find that quite often. Usually due to long throats in military calibers. I've never loaded for the 338 so, I can't help you there.
 

D21ALASKA

Beginner
Oct 29, 2013
171
23
I get pretty close to book velocity, sometimes I don't, reasons are case volume, bullet seated out long to touch the rifling will reduce speed. I just start off .005" off the lands, and work up slow. I once had to go almost 4 grains more than book max to get similar book velocity for my 7 Mag. Sometimes I end up using a grain less powder and get max book speeds but I prefer accuracy over speed.
Thanks Tack. Yeah I'll definitely take the accuracy over the speed. A 210PT going 2800+ will still lay it down. Interestingly enough I'm actually a bit shorter than book at the moment on this one. Though I've definitely run into it with longer than book in the past on a couple. We'll see what the accuracy is like, though I'm not seeing much consistency in speeds between loads either. Going a full half grain between each but still some pretty big up/down swings.
 

Blkram

Handloader
Nov 25, 2013
1,823
154
There is generally going to be variations in what the book says and what we will get in our rifles, and this is going to vary from handloader to handloader. It is nothing to really worry over, as many of the variables are beyond your control, and as such, should not be fretted over.
The main variables are going to be the following:
- variations in chambers and barrels between your rifle and their test barrels and chambers;
- variations in the lots of powder that you are using vs their powder that they are using;
- variations in the lots of the primers that you are using vs their primers;
- variations in the case capacities of the brass that they used vs the brass that you have used to assemble your loads for testing;
- variations in the amount of crimp that they have used in developing the loads they have tested vs what you have on your assembled test loads; and
- variations in the run out of their assembled loads compared to the run out of the loads that you assembled and tested.

These, along with other variables I have not listed in this quick list, can all account for the variations in the results that they have received as compared to your results. Without more specific details that they do not provide in their reloading manuals, you will never be able to exactly duplicate their results.
If you get close; great!
If not, don't worry about it too much...and keep trying until you get the results that you are specifically looking for, while maintaining safe practices.

Myself, I look for accuracy over velocity. If I can achieve desired velocity, along with great accuracy, I am even happier!
But I do have loads that do not come close to the anticipated velocity, but are accurate, and have worked well on game, when used within reasonable limits. By this, I mean that I am using it on game for which the bullet, at its actual velocity and energy figures obtained, are designed to perform within.

I also know of a few who have had rifles that shot slower than expected (approx. 200 fps, like you) while the barrel was being broken in, and finally showed their true potential after a few hundred rounds! If your 338 is newer, it may be a similar situation that you are encountering.
 

D21ALASKA

Beginner
Oct 29, 2013
171
23
I appreciate you taking the time on that write up Gil. I'm not overly concerned about it. It's an old rifle in years, circa '69 Model 70 super grade, but young in round count so that may very well be something to it. My '06 was the same way.
 

Blkram

Handloader
Nov 25, 2013
1,823
154
Nice rifle Ben.
Hope it serves you well and you create lots of great memories with it!

I have really enjoyed the 338 Win Mag over the years, using it on moose, elk, grizzly and bison. My current 338 is a fairly new to me LH Sako AV with the factory laminated stock and shoots Federal factory 210 gr Partitions into 1" groups. Still need to try out the 225 gr AB ammo to check on its performance.
While I also have and use rifles in 338 federal and 338-06, when it comes to the larger game such as grizzly and bison, the extra performance of the Win Mag is comforting and confidence inspiring.
I have installed LimbSavers on my 338 Win Mags, and it has greatly reduced felt recoil and makes them more pleasurable to shoot and practice with sufficiently to improve one's ability to shoot the rifle accurately from various shooting positions. (A great thing with my bad shoulders!)
 

D21ALASKA

Beginner
Oct 29, 2013
171
23
She should definitely serve me well Gil. Picked her up for a song about a year ago as I needed to replace the stock. Had a catastrophic break at some point that someone tried to repair but it didn't pass muster with me. Had my gunsmith go ahead and drop her into an express stock with a pillar and bed job and I went ahead and had him cerakote it as well. Not quite as pretty as she was but still a very nice rifle that will be a bit more forgiving now when it comes to the elements up here in AK. If I draw my goat tag in a couple weeks for this fall I may just have to lug her up the mountain for one...
 
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