Case Lenght Question

[hemidart]

I am reloading .223 R-P brass for an AR and a Mini-14 trim to lenght is 1.750 and max case lenght is 1.760. What is the issues with loading cases that measure too long say 1.770 is this a safety/accuracy issue ??????
thanks
Pete......

 

[Buck45]

Can lead to high pressure quoting from page 22 and 23 Hornady Loading Book. You crimp the mouth of the case onto the bullet The overlength case allows pressure to build to a dangerous level. This all happens in the throat of the barrel.

Just an add on it will not allow the bullet to be released from the case mouth. Hence pressure increases to dangerous levels

 

[Onagoth]

Excessively long cartridges may also not fit in the magazines properly, and might not chamber properly as well, although not likely in the situation you describe

 

[Shelldrake]

With a bottle neck, if you case is too long you risk the case mouth entering the throat of the chamber, which will risk an increase in pressure (perhaps dramatically).
With a straight walled case that headspaces on the front of the case (like 45 ACP), and if the case length is too long, then you may not be able to chamber the round.

 

[jethunter]

Maximum means.... maximum.

Yes - over length cases can increase pressures to dangerous levels, and yes - you need to trim. You can get a Lee trimmer setup for $10 or so for the initial setup. The Lee manual trimmer isn't fast, but it can be connected to a drill which speeds things up considerably. Usually you only trim brass once and they are good for multiple reloadings. Exception might be if you full length resize every time and use hot loads.