450 marlin

[nail]

I loaded up some 350RD cast with 44.0 gr and 45.0 gr of re-7 and at 100yds they shot a 11/4" group at 1640fps and was very happy.
I went home and loaded some more of the same load and back to the range and they were all over the target. The only difference that I noticed was the first loads were new not fired brass just sized and flared, When I resized the fired brass I felt a the expander going inside the shell,with the new brass I never felt the sizer going into the case but they were all full length sized.
What am I doing wrong, I never changed anything on the dies. Is the tension on the bullet a big thing with cast. Thanks Steve!!:confused:

[44man]

I use a hard boolit and a lot of tension in revolvers. You don't need it in a rifle and if your boolits are soft for hunting you are sizing when you seat the boolit.
This is where the Lyman expander will help and all you need to do is keep boolits in the brass if you have a tube magazine. A decent crimp will do it.
Get a larger expander and you should be OK.

[singleshot]

Both charges of re-7 shot the same group at the same velocity?

What was the contition of your bore? How many boolits did you fire initially? Did you measure the brass before and after to see if the shoulder is in the same place? What were the weather conditions on the two days? Were you firing from a bench both times supporting the rifle at the same point? What kind of rifle is it? Did you measure and weigh your boolits? What kind of lube?

It sounds like you're suggesting the brass was smaller after you fired it, hence the expander plug hitting the case mouth harder the second time around. What brand of dies? Just b/c you didn't change anything on the dies, doesn't absolutely mean the dies didn't change.

I have noticed more perceived force with dirty brass (residue on the INSIDE of the case mouth) than new or clean brass based on friction. How do you clean and/or lube your brass?

Boolit tension can certainly change things, less tension can give you incomplete ignition and lower muzzle velocity, thus higher point of impact. What was your MV on your second day?

[HangFireW8]

Well, I'm assuming there's no shoulder on the brass, before or after, and Nail is using a Marlin lever action. :)

Singleshot makes a point, though, there are a lot of things it could be besides bullet pull (neck tension+crimp). Primer changes, a leaded bore, a temperature sensitivity threshold, a stabilization threshold (slightly slower velocities causing boolits to fall below the necessary RPM for stabilization).

As 44man pointed out, there could be unintended sizing. As you noticed, the sizing dies for big straightwall cases often overdo the job, and we rely on the expander to bring the case back up to size again. It is quite possible to take as much as 3 thousandths off of a boolit through unintentional sizing in the seating process of a too-small sized case. Worst of all, it happens at the base of the boolit, where we need it to seal the most. Many straight-wall shooters "PFL" or Partial Full Length Size their cases, which just means they screw the sizing die out some. Others have neck sizing dies, same idea only you can screw the die in all the way but it's less hard on the brass.

Using Hornady dies on the 444 I had the problem of difficult seating, shaved copper and wasp-waisted cartridges. I had to flair the case a ridiculous amount to accomplish seating, and then I had cracks show up in fired cases after 2 reloads. I called Hornady up and they made me an expander die with an extra-deep seater. Not any wider, but it expanded the full length of the 265gr bullet and then some. That was when I only loaded J-words but boy, has that expander come in handy reloading cast! As 44man said, have you tried the Lyman M die?

I disagree a bit with 44man about bullet pull for rifles, in general he's absolutely correct, but if you intend to use your 450 Marlin cartridges in the magazine, you'll need at least a medium amount of tension and/or crimp to prevent the boolits being seated deeper by recoil.

I have a fair amount of experience with the other two Marlin big bore calibers. One difference is your bench rest- I always put my hand under the forearm while shooting. Resting the forearm on a somewhat hard benchrest causes a bit of bounce and some vertical stringing.

Another factor can be flinching- though this never happens to me and my big-bores. :) Despite my immunity to recoil :) I put 1" Pachmary Decelerators on my two Marlin big bores. I also cut the stocks slightly with a toe 2.5 degrees forward and a 2.5 degree slant on the butt. This nestles into my shoulder better, with more contact area and I don't get a bruise on my peck like I did with the stock Marlin configuration.

Tell us what you come up with.

HF

[singleshot]

Well, I'm assuming there's no shoulder on the brass, before or after, and Nail is using a Marlin lever action. :)
HF

Hee hee, not too familiar with 450 Marlin, thought for some odd reason it had a small shoulder. Since it's supposed to replace the 45-70 it makes sense it wouldn't.

I'm interested to hear the outcome of this one.

[44man]

Yes, you always need some tension and as even as you can get it, I agree but the rifle does not need to be as tight as the revolver.
I wasn't saying to eliminate tension, just find the right expander.

[nail]

Thank you gentlemen for your reply,s,I have read and heeded all of them.
Now I have a question, I have a lathe and milling machines and can make an expander for my die,s, I am shooting the Ranch Dog 350 sized to 360" What size should I make the expander. Thanks Steve!!

[HangFireW8]

Allow for .001" springback, more if the brass is only being sized .003-5", and be sure to make it deeper than the deepest cast boolit you'll load. Shoot for .001" or less under boolit diameter.