Small Rebated Boat Tail On 68 Grain 6mm……Tested Today

[JPB3]

Maybe what Tim was alluding to is it looks like the core seating pressure was light and not making the base fill out completely.. BUT BUT don't change a thing... Looks to be shooting very well, Congrats Jackie, glad you're still in the hunt. Merry Christmas, Sir!

Pat B.

 

[ShtrRdy]

Impressive!!

 

[boltfluter]

That's some first class shooting on your part! Nicely done. Always enjoy reading about your experiments.
Paul

 

[jackieschmidt]

Maybe what Tim was alluding to is it looks like the core seating pressure was light and not making the base fill out completely.. BUT BUT don't change a thing... Looks to be shooting very well, Congrats Jackie, glad you're still in the hunt. Merry Christmas, Sir!

Pat B.

I do my core seating pressure the way Randy Robinette and a few others advised.

As you seat the core, the jacket expands to meet the walls of the die.
It also grows shorter. However, as more core seat pressure is applied, and after it can grow in diameter as much as the die will allow, it will start to grow back in length. When it hits about .005 in growth, that is where I stop.

Of course, you can keep adding core seat pressure ,until the jacket pops. I have heard of bullet makers, the late Skip Otto in particular, doing just that, adding pressure until they pop a core, then back it back a little.
I do not prescribe to this practice.

Doing it the way I described will sacrifice perhaps 10 jackets and cores, but after it is set, you are ready to go.
Of course, there is also arriving at the correct amount of lube, if any, and of course getting the punch diameter perfect.

And then there is everything else

 

[Tim Singleton]

I do my core seating pressure the way Randy Robinette and a few others advised.

As you seat the core, the jacket expands to meet the walls of the die.
It also grows shorter. However, as more core seat pressure is applied, and after it can grow in diameter as much as the die will allow, it will start to grow back in length. When it hits about .005 in growth, that is where I stop.

Of course, you can keep adding core seat pressure ,until the jacket pops. I have heard of bullet makers, the late Skip Otto in particular, doing just that, adding pressure until they pop a core, then back it back a little.
I do not prescribe to this practice.

Doing it the way I described will sacrifice perhaps 10 jackets and cores, but after it is set, you are ready to go.
Of course, there is also arriving at the correct amount of lube, if any, and of course getting the punch diameter perfect.

And then there is everything else

That method sounds like what you typically see with flat base core seaters the getting shorter then a little longer
But with a boat tail core seater they are longer from the start because of the length of the boat tail
Only thing that really matters is they shoot!
Yours are shooting great!

 

[Bill Norris]

I do my core seating pressure the way Randy Robinette and a few others advised.

As you seat the core, the jacket expands to meet the walls of the die.
It also grows shorter. However, as more core seat pressure is applied, and after it can grow in diameter as much as the die will allow, it will start to grow back in length. When it hits about .005 in growth, that is where I stop.

Of course, you can keep adding core seat pressure ,until the jacket pops. I have heard of bullet makers, the late Skip Otto in particular, doing just that, adding pressure until they pop a core, then back it back a little.
I do not prescribe to this practice.

Doing it the way I described will sacrifice perhaps 10 jackets and cores, but after it is set, you are ready to go.
Of course, there is also arriving at the correct amount of lube, if any, and of course getting the punch diameter perfect.

And then there is everything else

Sounds like you got a really good grip on your methods Jackie. The target is the proof every time. Keep up the good work.

 

[jackieschmidt]

Interesting stuff Jackie! How is the boat business.

We are set to have our best year of the past five years.

 

[dcali]

George Ulrich told me to put a flat of about .005" on the punch if I wanted to greatly extend the life of the punch. I haven't bothered - I just use as much lube as I can without causing issues to keep the point up forces as low as I can without sacrificing quality. I'm suspicious that rebated boattails do anything but ease manufacturing I have not tested that. but anecdotally, others who have don't seem to have found much to write home about. Punch life and durability is no small thing, though.

I also talked with George about making some concave boattails to increase the angle at the punch edge without resorting to a rebated boattail. But that winds up not making sense ballistically. It slightly increases drag vs a conical boattail.

The above is all in the context of long range bullets.