what increments when working out a load?

rhino519

rhino519

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at what increments you guys increase the powder weight when working out a load?
i use .5grain in regular calibers but now working on .300WM it seems to me not that significant, i'm thinking about going full grain beteeen different loads
 
The problem when working with a 300 WM is, as you approach a max level, the pressures SPIKE very rapidly. I'd suggest you stick to the 1/2 gr increments. There are a lot of standard loads but you should still approach them with care. I found the 300 WM to give excellent accuracy without very much difficulty.
 
OP one thing you really need to do is find out how powder density works. First and foremost it can't be loaded in relationship to the capacities listed. For instance, once you start increasing the load when you're close to maximum charges listed in the manuals things can get hairy very quickly depending on the cartridge you're loading. The loads aren't "proportional." The smaller the cartridge case the more careful you have to be. Pressures are fine until they aren't. The greater the density of the load the greater the danger of a pressure spike that may or may not cause issues.

In the case of the cartridge you propose to load for, 300 WM, I would start with a minimum load and work up from there. The first bump up would likely be to the intermediate of the min/max. In truth that's likely where where I would start. Magnum cartridges inherently shoot best near maximum loads for that particular rifle so a median load is a good place to start. In all honesty, if that load produces fantastic accuracy, that's where I would stop. The powder added after that point will give you a minimal change in velocity but increase pressures dramatically in some instances.

If your velocities are faster than listed in the manuals and your bbl is around the same length it usually means your pressures are spiking. Spiking pressures correlate to inconsistent velocities and therefore inconsistent accuracy. That is pretty much the best rule of thumb reloaders can use. Of course someone will claim they have a rifle that loves over max loads and I will admit the very odd one is out there. Often, they have significant "freebore." Weatherby used to have what I would call excessive freebore to counteract their over bore capacity loads. Basically pressure was allowed to bleed off around the bullet just after it exited the cartridge case. This led to inaccuracy in some cases where the freebore was to large in diameter or to long.

Then it depends on the type of bullet you're using. Monolithics really do a good job at higher velocities. I like them a lot. The thing is they are usually LONG for diameter and weight. This means more drag/friction in the bore and this increases pressures again. I always use starting loads with long for weight/diameter Monolithics. Even some of the ELD offerings with lead cores can give pressure issues.

There is more to it than this but this gives you some idea of what you're up against.

I have experimented with slower powders than are listed in the manuals in certain cartridges I feel will benefit from this. In most cartridges there isn't a noticeable increase in velocity but often a noticeable decrease. Usually accuracy is better but uses more powder. Again, it depends on bore diameter. Smaller bores seem to benefit the most from slower powders.
 
thanks guys, and thank you bearbunter
believe me i have no intention of going hot with the rifle i currently am working on, i think i am approaching it very carefully, especially since the powder (H4895) is not listed for this caliber
i'm going to start at 49gr and try 50 and 51, see how it goes from there
 
rhino519 said:
thanks guys, and thank you bearbunter
believe me i have no intention of going hot with the rifle i currently am working on, i think i am approaching it very carefully, especially since the powder (H4895) is not listed for this caliber
i'm going to start at 49gr and try 50 and 51, see how it goes from there
Click to expand...

4895 is a versatile powder but is more ideal for rounds like 223: There are loads listed for lightweight bullets but this seems to defeat the purpose of shooting a 300WM. You'll get better results with powder slower than H4350. Oh, and I neglected to directly answer your first question: I've worked in increments of 0.1gr, but typically between 0.2-0.5grs.
 
rhino519 said:
thanks guys, and thank you bearbunter
believe me i have no intention of going hot with the rifle i currently am working on, i think i am approaching it very carefully, especially since the powder (H4895) is not listed for this caliber
i'm going to start at 49gr and try 50 and 51, see how it goes from there
Click to expand...


As mentioned H4895 isn't the ideal powder for the 300WM. It will work and if it's the only powder you have or can afford then go for it. My real issue with it is you likely won't find an accurate load because it won't have decent powder density in the case before it reaches maximum pressures. Poor densities lead directly to poor accuracy.
 
thanks guys
yes, this powder is just a try out, only had that and varget, and since i had some good results with .303br in 180gr bullet i thought i will give it a try
i should get a better powder, i agree
 
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