Developing a .404 Jeffery Cast Bullet Plinking / Practice Load

[Scrumbag]

what dia is your bore? although you're sizing down, are you just going to the fmj dia, or actually you're correct fit dia?

unfortunately shellhouse is a comercial manufacturer, they can't just use lee moulds, If you're willing to drop the money on a die to go with their machinery I'm sure they'll seel you correct bullets, but they aren't going to invest in one for one customer.

so are you trying to make a plinking load (ie low power, easy to shoot lots of at a middling accuracy) or are you wanting to find a cheaper source of bullet and happy to try lead (ie get close to full velocity and behaviour of the expensive bangs)?

if you just want to mess around with plinking, then that bullet, sized appropriately and a few grains of fast pistol powder will get the job done and get you punching paper.

Well, 1100fps plinker, good, if I can get more, better!

[Scrumbag]

I would recommend giving them a try as is post sizing, if you are just sizing to the recommended diameter rather than actual diameter then you could be lucky.

If you are not lucky then at least you will have some information to work from.

Proper bullet fit is the key to accuracy and no leading. Adding all the bells whistles and current fashion trends like powder coatings are at best a third hand elastoplast that will in no way address the reasons for any problems.

Interestingly most of the top cast bullet bench rest shooters will use high antimony bearing (very hard) alloy to get the benefits of its excellent castability and fill out giving extremely uniform bullets.

However they will have a mould cut to exactly fit their chamber/throat rifling with their chosen alloy or in extreme cases have barrels cut to fit their bullets, either way with bullet fit the alloy becomes irrelevant.

Unless we have that happy marriage of bullet and barrel then hard alloys are not an option and leading will occur, soft lead alloys have an instant fit at time of obturation, managed by the bullet "lube", giving lead free accuracy.

That sounds very sensible. I see Lee seem to currently have .425 and .426 dies and punches currently in stock so might have a chance for some tuning of diameter.

Scrummy

[andrew375]

First thing to do is to find what the groove diameter of your bore actually is. Apart from anything else you might find the bore is larger than you think it is and you don't need to reduce the bullet diameter at all. If you seat a .430 diameter bullet will the round chamber easily? Where oversize bullets cause excess pressure is where the neck of the case becomes so big there is no clearance between it and chamber to allow it to expand to release the bullet. In practice however, except with some "match " chambers, the diameter of the neck portion of chamber can be rather generous.