Trying to start to determine Max COAL for my 7x57 I followed the advice below:



"Size just the tip of the neck of an empty case and seat the bullet out far enough so the lands will push the bullet back when the dummy round is chambered in the rifle. I then measure dummy round and back off additional .010" and start testing from there moving backwards."


When I did that the bullet did not meet the lands at all and it didn't get shoved into the brass.

It is a 1955 Hunsqvrana 4100

I think I will just load the bullet the minimum (one bullet diameter) and see how that shoots.

With that in mind I'd probably start with the max length your magazine will acommodate with a minimum charge and go from there.

This just means that your throat is either worn or cut longer than the bullet you are using. I have Match AR barrel that has the same problem. It will stay on paper at 1000 yards, but doesn't shoot tight groups at 600 any more.

I loaded the wth the junction of the boat tail and bullet body to the base of the neck. This also gives you maximum powder capacity.

quote:

I think I will just load the bullet the minimum (one bullet diameter) and see how that shoots.

That is a good plan as long as it feeds ok.

If your bullet is a boat tail, switching to the equivalent flat base will allow seating the bullet longer while keeping an adequate length in the case neck.
But check feeding as always.

What bullet are you working with? Most of the 7x57s are throated to accomodate the heavier bullets.
As posted, your limits may well be the magazine box.

The bullet is a 139 grain Hornady Interlock flat base.

The magazine is extremely generous.

My buddy who gave me the rifle also gave me his pet loads which were 139 grain Hornady SST bullets loaded extremely long, with less than a bullet diameter in the neck and they still fit in the magazine.

These Husqvarna 4100 rifles in 7x57 are reputed to be long-throatd. Seems that is true.

There is in 'one caliber deep' rule but there is such nonsense spouted on the web. A lot of cartridges don't even have a neck one caliber long.

I seat mine even with the base of the neck and check the mag length.
I use mostly flat base bullets in my 7x57.

Close the bolt on an empty chamber and insert a cleaning rod from the muzzle (the rod without a brush must have a flat end not a hollow threaded end) With the rod down the bore and held to the bolt face mark the rod with a fine tipped pen at the muzzle.
Open the bolt and insert a projectile using your finger or a case with a sized neck to push it as far as it will go into the chamber and touching the lands. By rocking the cleaning rod in and out while holding the projectile in at the breach end you can lightly feel the projectile against the lands. Mark the cleaning rod again at the muzzle. The difference between the marks on the rod is the maximum overall length the cartridge can be with the bullet just touching the lands. Deduct off that measurement the land clearance you want and set up your seating die to give the COAL for that particular bullet in that particular rifle.

Simple stuff, no need for any other fancy measuring devices. Of course as pointed out by other posters, your magazine may not accommodate a cartridge with the true OAL for a particular bullet combination so you just have to seat the bullet to suit the magazine.

I've heard of one other trick for the 7x57 as they were mostly set up for longer bullets.
Seat a longer boattail BACKWARD enough to hold it in place. Chamber carefully and close the bolt. It will hit the lands and give you the exact depth. The 139 is way shorter than the 154 & 175 that was so widely used.

Go to this site for an easy way to determine OAL. Remember when changing bullets, you need to redo it for that bullet. Go to Reloading/Shooting Tips and then to Best OAL.
http://www.larrywillis.com/

Happy Reloading!