TexasCHLforum.com

OK, so for the .308win my Hornad 7th ed. loading manual specifies a max of 43.3 grains IMR4895 for the .308 win. 168gn a-MAX with a 2.8 COL.
I am loading at 2.95 COL, .308win, 168gn a-max, with 43.6grains IMR4895
Think this is bad? It is not much over MAX (.3) and there are no signs of over pressure. I am assuming the slightly longer cartridge length is helping with pressures as well.

I am doing this to match velocity of my favorite hornady amunition, as it seems to stabilize the projectile well at this velocity in my barrel.
2650fps when tested the other day.

Any thoughts???

Short version:
# factory ammo typically uses powders or lots not available to reloaders so it may not always be possible to exactly duplicate factory loads safely.
# checking primers is not a 100% reliable method of 'reading' pressure
# different components (brass, bullets, primers) may yield different results for the same load

Longer version:
Welcome to the semi-scientific world of handloading. I always recommend consulting multiple sources for load data and owning at least 2 loading manuals. Different vendors will have different equipment for measuring velocity and pressure which results in different load data; firing the same load using the same components in 2 firearms of the same make and model may result in different results due to manufacturing tolerances, the phase of the moon and possibly which gods you pray to (if any).

Its been 'my experience' that Hornady data tends to be a bit on the conservative side. If I look at the Hodgdon data book (they now own IMR powders), they list 45.0gr of IMR 4895 for a 168gr HPBT bullet in .308Win for a velocity of 2758fps and a pressure of 58,000psi. They also note its a compressed load and they use a COAL of 2.800". No information on test firearm or barrel length is provided.

Without seeing your brass, or researching more load data it 'sounds' like you should be ok.

Disclaimer:
I am in no way endorsing or suggesting whether you should or should not continue to use your current load. This data is provided strictly for informational purposes and under no circumstances do I recommend its use nor guarantee the accuracy or safety of the data.

:-) :-) :-)

Lots of heated opinions on this subject on the reloading forums. Oh well, it's cold out and I can stand a bit of heat.

.3 grain over is virtually insignificant and well within the tolerances of modern rifles...changing a primer is probably going to make a bigger difference, BUT:

New reloaders stop reading here!

I consider myself an advanced reloader...both due to a engineering and chemistry background and 10+ years of experience with many calibers.

I do dabble in over max loads, but barely and only in very controlled and very limited circumstances.

First rule: Strong actions only, meaning modern bolt actions in proven good condition, with factory chambers. Pistols, lever/pump/break actions, most milsurps, shotguns, etc. do NOT have the safety margin inherent to modern bolt rifles. Don't do it.

Second rule: No more than a few % over max. (This is VERY subjective and a personal rule, YMMV) Pressure is not linear to powder, so small increases in powder make for large increases in pressure. Use VERY small increases in powder as you work up.

Third rule: Only use data from manufacturers that use test barrels, not factory rifles (Sierra, for example) for their testing. You want data that is more repeatable, and that means lab spec rifle barrels and chambers.

Last rule: be exceptionally careful with most of the new chamberings like the WSM's, WSSMs, etc. (Many reasons, from large diameter cartridges exerting more bolt thrust, to already redlined pressures)

Here's my logic: Published loads are based on SAMMI minimum spec chambers and barrels. These dimensionally tight chambers and barrels tend to reach max pressure sooner than factory chambers. This forces the test lab to err on the conservative side. Also, the same rifle that is chambered for the 60kPSI 308Win is also probably loaded for the 65kPSI WSM family, giving you a second safety margin.

Be advised that you are now into the yellowline...approach such hazards with all the care they warrant. Pink skin is soft, ordinance steel isn't. The tiny bit of velocity isn't worth it to me, but to reach an accuracy node I do it all the time. You must understand the risk and make your own decision. It isn't my face behind the bolt...

Thanks for the information. It helps to have some more opinions on the subject.

CDH wrote:Lots of heated opinions on this subject on the reloading forums. Oh well, it's cold out and I can stand a bit of heat.

.3 grain over is virtually insignificant and well within the tolerances of modern rifles...changing a primer is probably going to make a bigger difference, BUT:

New reloaders stop reading here!

I consider myself an advanced reloader...both due to a engineering and chemistry background and 10+ years of experience with many calibers.

I do dabble in over max loads, but barely and only in very controlled and very limited circumstances.

First rule: Strong actions only, meaning modern bolt actions in proven good condition, with factory chambers. Pistols, lever/pump/break actions, most milsurps, shotguns, etc. do NOT have the safety margin inherent to modern bolt rifles. Don't do it.

Second rule: No more than a few % over max. (This is VERY subjective and a personal rule, YMMV) Pressure is not linear to powder, so small increases in powder make for large increases in pressure. Use VERY small increases in powder as you work up.

Third rule: Only use data from manufacturers that use test barrels, not factory rifles (Sierra, for example) for their testing. You want data that is more repeatable, and that means lab spec rifle barrels and chambers.

Last rule: be exceptionally careful with most of the new chamberings like the WSM's, WSSMs, etc. (Many reasons, from large diameter cartridges exerting more bolt thrust, to already redlined pressures)

Here's my logic: Published loads are based on SAMMI minimum spec chambers and barrels. These dimensionally tight chambers and barrels tend to reach max pressure sooner than factory chambers. This forces the test lab to err on the conservative side. Also, the same rifle that is chambered for the 60kPSI 308Win is also probably loaded for the 65kPSI WSM family, giving you a second safety margin.

Be advised that you are now into the yellowline...approach such hazards with all the care they warrant. Pink skin is soft, ordinance steel isn't. The tiny bit of velocity isn't worth it to me, but to reach an accuracy node I do it all the time. You must understand the risk and make your own decision. It isn't my face behind the bolt...

very well stated
when i do the loads and want to tweak an existing combination i sneak up on the additional powder very slowly and run ten or more test samples before i run any large numbers.
I found that even before i approach the max powder i have hit a nice load that meets my demands for range or plinking

for personal defense i just buy factory loaded ammo. I dont use enough pd rounds to warrant loading them my self, hopefully i never use em in self defesne but waste em at a range targets instead

the joy of reloading for me is relaxation and relearning forgotten physics