I have a 300 win mag that appears to have a slow barrel/chamber. Velocities seem to be pretty slow with all loads. With 180 gr bullets and IMR 4350 with 72 gr of powder 2850 is all she will do. Book says 3100 is possible. With 200 gr bullets should be able to get to 2950. Using IMR 4350 and one gr over book max I get 2840. Using H4831 and 200 gr bullets. 2750 is all. So the question is how much over are you willing to go? Do you keep adding powder until you get to book max velocity? At some point I assume case capacity and how compressed can powder get will become an issue. What do you think. All opinions welcome. D

1) Never believe everything you read.
2) Have you verified your chronograph is accurate?

"So the question is how much over are you willing to go?" As far as I can without getting into dangerous territory, OR LOSING ACCURACY!!!

"Do you keep adding powder until you get to book max velocity?" Keep adding until you get the velocity you want, (with acceptable accuracy!!) or you reach a point where you cannot add any more! This can happen long before you get to the "book max", or not!!

At some point I assume case capacity and how compressed can powder get will become an issue. Some degree of compression is quite acceptable. Just don't compress powders to the point that your case shoulders bulge, or where the compressed powder charge pushes your bullets back out!! "What do you think. All opinions welcome."

As Bob Hagel once wrote, "Every rifle is an individual, and what proves to be a maximum load in one may be quite mild in another, and vice-versa." He was referring to the FACT that one never knows what a maximum load will prove to be in any particular rifle!! unless he works up to that load with that particular rifle, using a specific set of components - bullets, power, primers, and cases!

If you load to a point that is labelled as "maximum" in the reloading manual you are using, it is a fact that this load was maximum in the test rifle, but may or may not be maximum for YOUR RIFLE!! All you can be sure of is that the load was considered to be maximum by the person developing the data, in the specific rifle and with the specific set of components that he/she was using on a given day!

To illustrate this point further, I have seen a specific load in a particular manual labelled as being "maximum", then found another "maximum" load for the same powder type, same bullet make & weight, same cases and primers, in a different manual and there was a significant difference in the weights of powder specified in the two different books! So, under such circumstanes, which do you consider maximum?

These days, I choose to do my own determination of what is MY maximum in MY rifles by workup. I start at a book-recommended minimum load, then work up in 1/2-grain increments until one of two things happens: I either get the accuracy I want, (ACCURACY is more important than a couple hundred FPS in MV!!) or the load starts to show definite signs of being too hot. These signs show up BEFORE you start blowing primers!! If I reach an acceptable accuracy level before the load is too hot, I quit the workup, and use that load. If I get signs that the load is excessive, I stop, and reduce that charge 5%. If in this workup, I get to unacceptable power levels before getting a load that is accurate enough to be useful, I change a component (usually the bullet or powder type), and start the workup over!

Only change ONE COMPONENT at a time, so you can ID what was wrong with the unacceptable load!

If I were working up a load for a .300 Win. Mag., I would not be satisfied with a SAFE 180-grain or 200 grain MAX. LOAD that did not beat a .30/'06 by at least 100 FPS! IF your .300 Winny won't do this safely (it PROBABLY will, but it is possible that it won't), sell it and get a .30/'06!!

I consider any of the 4350 powders to be too fast for the .300 Win. Mag. I recommend H4831, RE22/25, Norma MRP, or IMR 7828 for the .300 Win. Mag. and the 7mm Rem Mag.

El Deguello addressed all of your concerns and did it very well.

I would add IMR 4831 to his list of powders. It has given me good results with 180 gr. bullets in a 300 Win Mag.

If I see signs of excessive pressure, I only reduce my load by 1-1.5 grains, and check it again. Some rifles are more accurate with a borderline-hot load.

quote:

El Deguello: Some degree of compression is quite acceptable. Just don't compress powders to the point that your case shoulders bulge, or where the compressed powder charge pushes your bullets back out!!

As an aside it's acceptable to drop half the powder and compress it and then drop the second half and compress that with the bullet. It's surprising how much slow burning powder one can get in the case this way.

El Deguello.....well done....excellent post!!!

Whats the length of your barrel compared to the one used in your manual?In a magnum,a shorter pipe makes a big diff. Secondly are your bullets moly coated? If using coated bullets one can sometimes experience a speed drop due to less pressure build,thusly faster powders are required,with tighter crimps. Thirdly, published data is corrected back to values that leave the environment out of the equation. One of which is calculating back to the muzzle.