I've always used winchester brass but have a little once fired federal that I'd like to use in .300 wm. I suspect the winchester has slightly more internal capacity but not sure. What has been your experience, and if I'm correct, about how much should I have to back off in powder charges in comparison to win. brass? thanks

It is true WW brass will often/usually have higher capacity vs other domestics. Also, often enough Fed, Hornady, and RP are close. Past experiences with .300 Win would suggest a 1 grain reduction of starting load, then chrono, etc, etc.

But there's a better way. Trim once fired WW and Fed cases (that were fired in your rifle - not someone else's) to the same length. Then fill with water and weigh. Don't forget the trim to equal lengths part.

A quick/dirty simulation substitutes a fine grained ball powder like H335 or 748. To somewhat mitigate against powder's compression apply the same fill technique on all test cases.

Case weights are another way you can kinda get at it, but less accurate IMO. Very roughly figure 14 gr metal/grain of H20 capacity. I only do this for .308 now. Seems to work there.

thank you much Sam

470NE brass for Federal ammo is made by Norma and soft. Not sure about pother brass.

I really like the Winchester brass for my 7mm08 & 280 fire formed to AI.

weigh them.
the weight difference in percentage is your percentage difference in powder weight.

Interesting question and something I have dealt with not too long ago.

I used Winchester brass for years in 338 WM and decided to give Norma brass a try.

I weighed 10 virgin Winchester cases and 10 virgin Norma cases and the average weight turned out to be:

Winchester 231.2 grains

Norma 208.7 grains

I figured the Norma brass either had a larger case capacity or was thinner overall than Winchester brass because it weighed less.

I worked up to loading the Norma cases with the maximum powder charge weight of IMR 4350 I had used in Winchester cases for years. After experimenting with two different lots of IMR 4350, my chronograph informed me, I needed to increase the charge weight in the Norma cases by one grain of powder to achieve the same velocity I had gotten from the Winchester cases.

Accuracy with the higher charge weight in the Norma cases proved just as good as the Winchester cases. Presumably, because the velocity remained close to the same.

I don't know where Federal brass falls on the weight/capacity spectrum but Winchester brass is heavier in 338 WM than Norma. In 30-06, Winchester brass is lighter than Lapua but heavier than both the Norma and Nosler brass I weighed.

Let your chronograph be your guide when working up a load with different brass and you'll be safe. Hope this helps.

quote:

Originally posted by Lamar:
weigh them.
the weight difference in percentage is your percentage difference in powder weight.

I agree, weighing them is great, and much better and less messy than water.

I have a lot of Ferderal brass, and it is extremely soft and not good brass at all IMO..My 99 Savages in .308 get head separation on the 3rd loading, sometime the 2nd..were as Win gets a trim on the 4th and or 5th reloading and will go to 7 or 8 reloads without a problem..they anneal or toss and buy more brass. I have a bucket full of once or twice fired Federal brass that I just no longer use.

Federal and Bertram is the only brass I have ever had a problem with..Loaded Federal factory ammo is very accurate and good options for bullets but its not a handloaders choice IMO. It is somewhat better when used in bolt action rifles, but by comparison its still inferior.

I use Federal and Winchester brass in my 300 Win Mag and 338 Win Mag.
Both brass produce excellent groups however the Federal is producing slightly faster speeds at what I am sure is higher pressure.
This tells me they are smaller in capacity.
Both brands are holding up well.

I agree regarding weight and internal capacity of Winchester brass. For this reason I prefer Winchester brass in my .222 Rem with slower burning powder and where the case capacity of other cases like Sako and Lapua are just too small. I have found Winchester brass to be of good quality.

quote:

Originally posted by Lamar:
weigh them.
the weight difference in percentage is your percentage difference in powder weight.

Not necessarily. It is possible for the extra brass on the heavier case to be distributed somewhere other than where it reduces the combustion chamber. If it is in a thicker rim or shallower extractor cut, then a heavier case could still have the same or even greater capacity than a lighter case.

Regardless, it is unlikely that the difference in WIN and FED is enough to cause a change in pressure sufficient to give a problem. That is not to say, however, than one might show "pressure signs" when the other doesn't simply because the heads may be of different hardness, therefore one allows case head expansion before the other does.