Load development ?

[duckaholic25]

I will be getting my first custom rifle in a week or so and wanted to get some opinions. Is it ok to use new brass for the load development or do I need to use the once fired cases from barrel break in. I would like to use new brass so I don't get to many shots on the first cases but will if I need to. Thanks

 

[Trnelson]

Is the fire-formed case substantially different than the sized case? As in Ackley Improved vs standard SAAMI chamber? Fill and weigh a sized case with water and do the same with a fired case. Are you planning to neck size or full-length size at reloading?

 

[duckaholic25]

Its a 300 win mag. Just gonna neck size unless the bolt starts getting hard to open.

 

[Trnelson]

IMO, you are on the right track. Do your load development with those fired cases. Then fire-form the rest. I run a 30/338 Winchester wildcat (based off 338 Winchester case) very similar to the 300 Winchester you are using. I've found the fire-formed brass to hold about a grain more powder, depending on the manufacturer and the lot. I sort them according to brand first, then again by weight. Just as you've stated I bump the shoulder when bolt closure becomes stiff. In my rifle, accuracy is disernably affected. I fire-form with 12g of Unique capped with COW and a canning wax plug lighted with the cheapest large rifle primer I can press in the case. Have fun be safe.

 

[RHC]

If I were you, fire all the new cases with cheap bullets and a random, but safe powder charge and fireform them all to your chamber. One of the good things about this is you get a little trigger time. How are you planning to work up a load?

 

[duckaholic25]

I plan on using Dan Newberrys optimum charge weight. At least that is what I have been doing and it seems to work well. I have never done the ladder method but I'm not opposed to it. Also I forgot to add the chamber is saami spec I just had it throated a little longer.