7mm REM MAG

[rabbit20]

got a quick question that I hope I am right on.

I ordered a RCBS Precision MIC to measure the brass for reloading and my brass was larger than the Dimensions according to ANSI (American National Standards Institute) According to ANSI the brass Dimensions from Base to the datum point on the shoulder should be 2.1253 to 2.1353 inches. After FL resizing my brass even to the smallest possible size its still long. I measured factory ammo and it was under ANSI by 15 thousands of am inch. I just want see if anyone else has come across this and if there is anything I need to worry about.

[okie2]

To start with there is no 2.1253 to 2.1353 inches on a 7 mag brass case
to the shoulder is 2.040 and to the neck shoulder point that is 2.228
and over all is 2.500.
Now you say on re sized brass you get .015 longer is this after fired in your gun?
make it clear what you are doing if you want some help.
here is your case dimensions and load data for 7 rem mag
http://ammoguide.com/cgi-bin/ai.cgi?sn=fWugXsfuft&catid=13

[rabbit20]

Need a UN and PW for that link. And the measurements that I got are from RCBS's manual that has the ANSI chart for all the different calibres. And the measurement is not the base of the shoulder or the base of the neck. The measurement is the datum point which is half way up the shoulder. Once again this is according to the manual from RCBS

[nova1194]

7 rem mag head spaces off of the belt, not the sholder, as long as it chambers in your rifle easily after its resized I wouldnt worry about it. The longer brass wil help it fit the chamber better, with less slop than factory ammo and may help accuracy.

Mike

[rabbit20]

7 rem mag head spaces off of the belt, not the sholder, as long as it chambers in your rifle easily after its resized I wouldnt worry about it. The longer brass wil help it fit the chamber better, with less slop than factory ammo and may help accuracy.

Mike


Ok thanks mike...have been reading about reloading and head space and all that and was concerned because the measurements from the factory to resized are pretty far off. I think im good now. I just done want to over work the brass thats all. Have never seen what a separation in the brass does to a rifle.

[okie2]

even if you think it head spaces off th belt you still need to get your die set to the same as your fired case from that chamber.

[jwolf]

The dimensions you stated are correct for the 7mag. If your fired cases are longer, then the gun they were fired in must not be headspaced correctly. It is also normal that unfired new cases be small. Most new brass and new ammo I measure is anywhere from .011 to .018 thou. shorter than min. ANSI. I'm guessing so they will chamber in anything. If you suspect your Precision Mic is off, you can put a 7 Rem mag Go Guage in it and it should measure "Zero" (The ANSI minimum 2.1253)

[rabbit20]

wolf, I think im good. im within the ANSI specs. I am 6 thousands of an inch over the min and 4 thousands of an inch under the max.