core seating

[Liseo]

Hi guys

New to the swaging, so a lot of doubts.

I received a 224 swaging dies from Blackmon , and I am using the J4 jackets.

My problem is that a feel different resistence in the core seating operation. I have the cores with very uniform weight, so I believe that this isnt the problem. Its necessary to separate the jackets by weight to avoid the problem? The difference in the ogive length is 0.010" from some bullets. Anyway, with a custon 223 rifle, I got very small 5 shots groups, in the .25" to .50" range.
But this variation bothers me.

Any thoughts?

Sorry for the bad english...

[Hickory]

The difference in pressure while seating the core may be do to air trapped in the jacket behind the core.
After seating the core, you can separate them by the amount of resistance, and check the weights.
You may find little or no difference.

[Liseo]

The difference in pressure while seating the core may be do to air trapped in the jacket behind the core.
After seating the core, you can separate them by the amount of resistance, and check the weights.
You may find little or no difference.

Hi Hickory

What can be done to avoid the trapped air? Maybe a small diameter core?

Thanks

[Hickory]

My experience is: not much.
But you can try seating the core slower,
giving the trapped air a chance to escape.

[Liseo]

One more question...:confused:
In your experience, the trapped air could cause accuracy problems, due to some imbalance ?

[Reload3006]

Yes trapped air causes accuracy problems. Not noticeable to most but in bench-rest competition can cost you a match. Using a smaller diameter core and going slower in your seating operation can most times reduce the trapped air. Any time there is a void between jacket and lead or in the lead its self there are imbalances they are believed to affect accuracy.

[Hickory]

Yes trapped air causes accuracy problems. Not noticeable to most but in bench-rest competition can cost you a match. Using a smaller diameter core and going slower in your seating operation can most times reduce the trapped air. Any time there is a void between jacket and lead or in the lead its self there are imbalances they are believed to affect accuracy.

You took the word out of my mouth.:)

[PbHurler]

Using a smaller diameter core and going slower in your seating operation can most times reduce the trapped air.

Agreed!
Your cores should be a loose fit within the jacket, and should not stay there if you invert them. Also, your external punch should be sized in diameter, to the I.D. of the jacket at the point of complete compression / expansion of your desired core weight, with little or no bleed-buy. A loose fitting core & consistent seating speed should yield no trapped air.

Hope this helps

[DukeInFlorida]

The cores can fit tight or be loose. As long as "pneumatically" the air can come out.

Try to push the press to mechanical top, rather than "felt amount of pressure"

And, the presumption is that you are starting with core blanks that are over weight, and swaging the cores to a final weight PRIOR to placing them in the jackets. If you're using raw cores for final assembly, that's NOT the way to do it.

Lastly, the process that you use depends on what you are making bullets for. If you are going to be shooting in 1000 yard competitions, then make them as accurate as you can.
If they are for self defense, no worries on how perfect they each are.

My gun shoots them out at 720 rounds per minute, and I take SOME care in matching weights (cores to jackets), but always follow the other basic steps.. and get bullets that always hit the target. At 720 RPM, you don't get coin sized groups, but that's fine with me.

[Liseo]

Seems that my cores have a tight fit, as they dont fall out if I invert then. I put the handle to the mechanical point( dont know the right word) but the press is the one supplied by Mr Blackmon, so there not a mechanical top, as the handle hit the max pressure point, and after that, release the pressure. The lead core is good quality and thers is no bleed-by
Anyway, I intent to make BR quality bullets for my rilfles. I already have a very good results,(they shot almost as good as my Barts and Sierra bullets) but this variaton in the core seating pressure and ogive length make me feel unsure about my process.


I will try all sugestions and will report what I find out.

Many thanks

[felix]

The final diameter of the finished bullet AT THE PRESSURE RING must be the same for each round in a "lot". The final weight is least important when measuring for consistency at the target. It's all about keeping the pressure-over-time curve exactly the same when making the final bullet AND also when firing the round. Remember, it's the "Curve", always!! ... felix

[GerryM]

If your working with J4 jackets the weight of the jacket should be very uniform. Heres the formula to making great benchrest bullets.
Uniform core weights = uniform core seating. uniform core seating = uniform points.
If you are carefull and make sure everything is equal in weight {cores} then your core seating should go easily. Those upside down dies that Larry makes are pretty good .
A lot of problems occur when the core doesn't go all the way down to the bottom of the jacket. reloader and some others have touched on that.
Lube is the other Key. anhydrous lanolin is probably one of the best lubes along with that corbin lube. corbin lube also has lanolin in it and some others here have their own formula.
straight lanoilin will work very well. too much or too little lube can also be a problem. The pointing on larrys dies has a different feel then the other dies like BT and the ones I use. Detsch.
after a while you should get a technque that will work for you. It just takes practice.