Core length and jacket length

[Hammer]

Question for the Swage Sages: (Flat Base or Boat Tail Hollow Points)

Is there an optimal length/depth for the seated core in relation to the unpointed swaged jacket/core?

I have read it should not rise above the start of the ogive....Then the point forming would occur on pure copper jacket only.

I can see how that would work, but does it matter as long as there is open tips on the point of the bullet.

Also, is there a rule of thumb for how deep the hollow point should be if that is not the case...

When I swage .800 J4 Jackets to make 60 gr, 62gr and 64 gr bullets, I have varying degrees of success with getting the open tip to stay open....

Thanks
Ed

[onomrbil]

Core length is what it is to make weight. Not much you can do with that except to maybe try some different alloys (another can of worms) to take more room in the jacket than soft lead. Insufficient core will cause tip forming problems; excessive core and you have a lead tip instead of an open tip. I doubt I am relating anything you don't already know there... Perhaps you can try a conical core seating punch to help keep the tips open as I do from time to time. It gets lead into the nose when you don't have quite enough core and makes the point-form process go a lot better and gives you a true hollow point instead of an open tip. Cores, because of varying degrees of lead purity and consistency in your lead wire, end up being a sort of variable in the process thereby making what you want to know difficult. Get a LOT of one lot of lead or lead wire and experiment. That way you will have enough of a supply buffer to learn how it all works together and you can make consistent bullets from batch to batch, which is the name of the game.

[Utah Shooter]

Just before I go to bed... I remember reading something along the lines of this before. There is a correlation but will not get to it tonight. I will find it and post tomorrow!

[aaronraad]

Ed

Can you post a couple of pictures showing the failures you are getting? Picture vs. 1000 words etc. :smile:

There might be a cutaway image on the Corbin site or similar showing the seated core. I work on about 2/3rd's to 3/4's of the jacket length but it is very dependant on both your boat-tail to flat base finish and you ogive radius. Jackets can be stretched when forming boat-tails.

Regards
Aaron

[Hammer]

Thanks for the answers. It really isn't a question of failures; it is a point where the lead flows into the open point and is no longer an open point bullet. (i.e. - overloaded and now a lead tip). I have seen cases where some folks use .800 jackets for a 64 grain bullet and then some folks use the same jackets for 60 grain bullets. Diffferent ogives give different lengths as well. I'm just curious if there is a rule of thumb for a bullet weight and jacket.....

May be just too many varialbels......

I can take the same cores and the same jackets and produce (sometimes unrepeatable) lots of different styles and weights. Not sure if I am making progress or wasting lead and copper....

The more I read; the less I know!

Thanks
Ed

[Utah Shooter]

Shoot I wished I could find the information. It was something that was talking about how being dead on accurate in weight was not as important as the ration of lead fill in a jacket. I will keep searching.

Aaron do you remember this from the other forum?

[aaronraad]

Joe, it might have been from Saubier.

I recall a few lists of jacket and core weights from Corbin's Rediscover Swaging but the detail was most likely very generalised.