question about reduced .308 load

[crest117]

I am fairly new to reloading and I have been experimenting with reduced .308 loads for my Axis. The load I use most is 32.5 grains of H4895 with a 150 grain FMJ bullet. Excellent accuracy at 100 yards and very easy on the shoulder. I do not have a chrono and I would like to have some idea of the velocity of this round. Any ideas? I was told it should be in the area of 2200FPS but that was just a guess.

[adammiddagh]

2200 fps would be my best guess. Be very cautious about reduced loads.

When you have excess air space in a cartridge, you can run into a very dangerous condition.
I believe it is called Secondary Explosion Effect. The excess space combined with a slow powder, can cause the primmer to ignite the surface of the powder charge all at once. Can create extreme pressures with no warning.

If you get hangfires / delayed ignition, you need to re evaluate your load.

A better choice for reduced loads is a small charge of fast powder like trail boss, or google red dot for subsonics.

[jersurf101]

I have reduced IMR 4895 about 20% off of the max and have read this pwder is suitable for reduced loads. I was looking for something reasonable for me 10 year old. Do be careful. Loading down can be dangerous but I know that IMR 4895 is safe but have not used the Hodgon version.

[crest117]

For those of you who believe reduced loads can be dangerous, read Hodgdon's information on reduced loads using H4895. They clearly state that these loads may be reduced to as much as 60% of max. This means a .308 can be safely reduced to as low as a 27.5 grain powder charge. I even called Hodgdon and spoke with a tech who assured me that this was safe but he cautioned not to do this with any powder other than H4895. I still have not figured out how to determine velocity for these reduced loads without a chrono. I was hoping someone knew of a chart or program that could predict reduced load velocity.

[Robinhood]

If recoil is the issue then a lighter bullet is another component to experiment with.

[darkker]

For those of you who believe reduced loads can be dangerous, read Hodgdon's information on reduced loads using H4895. They clearly state that these loads may be reduced to as much as 60% of max. This means a .308 can be safely reduced to as low as a 27.5 grain powder charge. I even called Hodgdon and spoke with a tech who assured me that this was safe but he cautioned not to do this with any powder other than H4895. I still have not figured out how to determine velocity for these reduced loads without a chrono. I was hoping someone knew of a chart or program that could predict reduced load velocity.

Yes, No, sort of
As you stated, which powder is critical to the whole point of safety in reduced loads. Some are perfectly fine, others are quite another story. 4895 in the 308 isn't a powder that throws-up red flags. The Lee loading manuals and IIRC Lyman has some VERY helpful data to calculate reduced loads, and give an idea on velocity.**

Now the crux of the matter, velocity.
Only the now very old A-Squared manual listed lot numbers in the data they tested, compounded by the fact that Hodgdon won't tell you ANYTHING about the powders they resell. I know that it a popular number that gets thrown around for canister grade powder is burning rate variation around 1-2% max; that is False.
We have pressure traced many things in the 6.5 Creedmoor, and 308. Some powders are relatively consistent in burning rate, some... Well, there is a VERY good reason why every bottle tells you to "Drop loads 10% when switching lots".
Book data is meant as a reference, and NOT as a gospel.

So without a chronograph, there really is no way of knowing how fast something is moving. SAAMI minimum spec test equipment that data was fired in, will produce much different results than your mass produced chamber and barrel. Without knowing how your powder burns compared to what was tested, aggravates that problem.