Further example of load data requiring complete work up for YOUR rifle

[bewsher500]

Finally got some powder for my .308 and am setting about working up some loads in a range of bullet weights and shapes to see what it likes and give me some options
Powder of choice is N140
Bullets include:
PPU 150gr FMJ,
168gr SMK, 175gr SMK, 190gr SMK and
208gr AMax

often with load data the exact bullet is not listed and you need to look at the general weights and apply common sense to work up a range. but this just goes to show that the data is a best guess that you MUST work up to in your rifle

VV data is as follows:

150gr - 36gr to 45gr/47/48.4gr depending on bullet make
168gr - 36 to 42gr
175gr - 35 to 42gr
190gr - 37 to 42gr
200gr - 34 to 42gr (NB, no 208 listed)

now call me cynical but that data isn't worth the paper it is written on

50gr or 33.3% weight variation in projectile and the starting loads are within 3gr of each other!
With the exception of one set of data all the max loads are the same!!

comes with the caveat:
"LIGHT GREY TEXT BOX INDICATES MAXIMUM LOAD - USE WITH CAUTION!
LOADS LESS THAN MINIMUM CHARGES SHOWN ARE NOT RECOMMENDED"

Factor in changes in barrel length, leade profile, groove and bore diameter, primer burn rate, seating depth, crimping, chamber dimension, brass thickness and case volume and the variables in pressure could be considerable.

just further proves to me the need to work a range for your rifle based loosely on the manufacturers data.

Start low work up to your rifle's pressure capabilities

 

[paul o']

i use 45gr of h4895 with a 150 PH runs like a dream ,soon to run out so also will move all guns over to vit 140 the 6.5x47 also loves v140 and r15

 

[M275]

It's good practice to start low and work up, but the devil in me keeps asking "what happens with commercial ammunition?".

When you buy a box of 20 rounds, they don't give you 10 with increasing powder charges so that you can test the ammunition in your rifle before you use the 10 normally-loaded rounds. They give you 20 cartridges all loaded to around the maximum book load and off you go. Not only that, the companies all compete to offer the highest velocities for any calibre and bullet weight, so presumably push towards the maximum pressures that SAAMI, CIP and their lawyers will allow.

I've expended hundreds of rounds and hundreds of pounds over the years working up carefully to the maximum book loads, and never once had any problem. Flattened primers are normally seen with factory loads but rarely with reloaded cartridges at maximum book loads.

I'm not going to stop this practice, but I do sometimes ask myself why.

 

[bewsher500]

I've expended hundreds of rounds and hundreds of pounds over the years working up carefully to the maximum book loads, and never once had any problem. Flattened primers are normally seen with factory loads but rarely with reloaded cartridges at maximum book loads.

I'm not going to stop this practice, but I do sometimes ask myself why.

i disagree
I have hit pressure signs way off max book loads with some loads
especially heavy for calibre bullets

factory loads are tested by the thousands I would imagine until they are sure they will work in factory rifles

 

[Paul at Fechan]

can't trust the books, they are just a guide after all!! Lots of cross referencing though gives you a good picture but you can't just jump in with a mid hot to hot load, that's just bad form