Brass trimmed too short for my 7.65 x 53 ?

[mrappe]

I have converted some 30-06 brass to 7.65 Mauser for my 91 Argentine using an RCBS case forming die. After running them through a Lee full length sizing die I trimmed them with my RCBS Trim Pro to the trim to length that I found in a Hornday book of 2.08" but some how the last 2 or three some how came out as 2.07" and I have one that is 2.05" from when I was trying to set up the trimmer. How short is too short? I am not sure what the last 2 came out different other than the trimming stop rings slipped a little under pressure.

Thanks

[NavyVet1959]

A bottleneck cartridge like this head spaces on the shoulder. If you are a long range bullseye shooter, you might notice a difference, but I suspect that the vast majority of us would not notice a difference. From a purely theoretical standpoint, you will have less resistance holding the bullet in the case. This will result in less pressure developed before the bullet starts moving. This might then result in a slower powder burn which could then result in a slightly slower velocity. This would result in a slightly lower point of impact. If you are not hand weighing every charge and bullet, I doubt that you will notice.

[Geezer in NH]

You are looking to hard at this IMHO 2 thou is nothing when short. 30 to 50 years ago this was not measurable for the average guy.

[Scharfschuetze]

3 hundredths (.03") is half the width of a dime. That shouldn't be an issue unless you are planning to crimp boolits, then it would give you less crimp than the rest of your cases and thus a different pressure curve to some extent. As noted above, probably only noticeable at long range.

Given the 7.65X53's abbreviated neck length, it's probably not something you want to repeat, but you'll be fine shooting them as they are. If you are still uncomfortable with it all, mark the cases and then use them for sighters or bore fouling rounds while saving your correctly trimmed cases for the targets or game.

By the way, I also use the RCBS form and trim die to make my 7.65 Mauser cases from Lake City Ought-Six brass. It is hardened and it is designed to use a file for a proper trim to length after cutting of the excess brass. The file will only polish the hardened surface at the top of the die. Mine is nicely polished, but case length has remained the same for some 20 or more years using this procedure.

[mrappe]

I found that after filing then sizing that the length was too long.

[mrappe]

Also, I have found that many of the empty cases will not chamber fully or are too tight. I think that i might need to turn the case necks down or something.

[Scharfschuetze]

That could be due to excessive length of the case's base to datum line on the shoulder of the case after sizing. Are you using Lee dies? If so, several here have reported the need (including me) to take a few thousandths from the base of the die or from your shell holder.

I started with the shell holder route, but a case pulled through the thinned metal so I ended up taking a five thousandths from the base of the FL sizing die. That solved the problem. Larry Gibson reports that the Lee dies were actually proportioned for the 7.65X53 Belgian Mauser and that the Argentine Mausers have a slightly short head space dimension. I just received a set of RCBS 7.65X53 dies, but I haven't tried them yet as I generally just neck size my cases for cast boolit use.

[mrappe]

How did you take the metal off of the die?

[Patricklaw]

I'm anxious for this answer as well. Without a machine shop at my disposal how can I work a die? A belt sander may be effective but it seems pretty crude.

[Hardcast416taylor]

If you are worried about this difference in OAL, just measure new virgin brass that comes bulk like Remington for instance to see variance in length.Robert

[leadman]

When I was using Lee dies I took metal off the shell holder on a belt/disc sander. A file will work also. I use Hornady dies now for the 7.65 Belgian and it will size enough to fit all of my 7.65X53 and 54 guns.
There was a slight difference in the length of the Belgian and the Arg. from what I have read.
You may also want to leave your brass a little on the long side as it usually shortens when fireformed.

If you have continuing problems with the case not fitting in the chamber you may have to anneal the shoulder and neck of the brass to lessen the springback. Be aware that the "heat the neck red hot" method heats the brass too much with a possibility the shoulders will collapse during boolit seating.

I use 400 degree Templac marker and place the mark just below the shoulder. When it melts from the heat transfering down the case the neck is hot enough.

[30calflash]

That could be due to excessive length of the case's base to datum line on the shoulder of the case after sizing. Are you using Lee dies? If so, several here have reported the need (including me) to take a few thousandths from the base of the die or from your shell holder.

I started with the shell holder route, but a case pulled through the thinned metal so I ended up taking a five thousandths from the base of the FL sizing die. That solved the problem. Larry Gibson reports that the Lee dies were actually proportioned for the 7.65X53 Belgian Mauser and that the Argentine Mausers have a slightly short head space dimension. I just received a set of RCBS 7.65X53 dies, but I haven't tried them yet as I generally just neck size my cases for cast boolit use.

I never knew that, thanks for the info. It's been a while since I've loaded and fired my 09 Argie, I'll check it out soon.

[mrappe]

How do you take the metal off of the die evenly and measure the amount taken off?

[leadman]

It is difficult to take metal off a die if you do not have a lathe. My suggestion would be to use a marker and mark the bottom of the die while you spin it. Might be able to chuck the die in a cordless drill by the expander stud. The marker will give you a reference as to how much you have taken off.
Dies are hard so a file may not work. Sandpaper on a file or pad will work but will be slow.
It is much easier to take metal off the shellholder as these can be chucked up in a drill and most a file will cut. A piece of sandpaper on a flat surface taped down and then the shellholder worked in a figure 8 will help keep it flat.

[Larry Gibson]

How did you take the metal off of the die?

I use a grinder with a fine wheel to just take of the hardened surface. It can be done with the die in a lathe using a Dremel with a fine grinder also. I then face off the die bottom the correct amount. Best to remove a couple extra thou for final headspace size adjustment done with the die in the press. I bevel the die mouth slightly and polish ideology with the Dremel. Harder to describe than to do.

If you've a steady hand it can all be done with a bench grinder and the Dremel.

Larry Gibson