trimming the empty 7mm Mag brass

[dkbs]

Hello
Thanks for any help in advance.
My son is coming home from school this weekend and is anxious to reload some shells for his 7mm mag. Heres the problem. I have all the necessary equipment except the case trimmer, which is on back order.
His new brass measures 2.493". In his reloading manual it states Max. case length is 2.500" and case trim length is 2.490". Are these cases good to go since they are underthe 2.500"or do we need to get them down to 2.490.

Thanks
Dan

[HEAD0001]

Good to go as long as all the lengths are consistent. It is best to consistently trim before the first firing(or at least I do). But it is not mandatory. Tom.

[bronko22000]

Your cases should be fine as it. But they are getting close to max. And the 7mm mag generates a lot of energy which causes the brass to flow forward - thus the need for trimming. This flowing of the brass also causes another problem. The brass has to come from somewhere. What you will need to watch for is a bright ring just forward of the belt. This is usually a sign of too little brass in this area and upon firing will cause case separation. Most of the time this separation is a case crack in this area but can also be a complete separation.

[SJAdventures]

Good to go for at least one more time.

[eldeguello]

ORIGINAL: dkbs

Hello
Thanks for any help in advance.
My son is coming home from school this weekend and is anxious to reload some shells for his 7mm mag. Heres the problem. I have all the necessary equipment except the case trimmer, which is on back order.
His new brass measures 2.493". In his reloading manual it states Max. case length is 2.500" and case trim length is 2.490". Are these cases good to go since they are underthe 2.500"or do we need to get them down to 2.490.

Thanks
Dan

IF those cases have been processed-sized, primed, etc., and they are still under 2.500" in length, you can use them as they are. When they get to be over 2.500", then when you trim them, cut them back to the 2.490" length..........

When sizing the cases, if they are to be fired again in the same rifle they were shot in last time, it is best to "partially FL size" them which means that you set your FL die in the press so that just half of the neck or so is sized back down enough to securely hold the new bullet. This method prevents the cases from having the shoulder set back any each time, and should help prevent the incipient head separations described above by bronco........(This may or may not be a problem with your rifle-it depends on how tightly your chamber was cut.)

[eldeguello]

OOPS!!

[redgreen]

I always trim new brass to take any inconsistancy off of the necks. After a few firings, and they start to stretch, I cut them .004 under chamber. This enhances accuracy, but requires careful checking to make sure that they have not gone over length. If you trim them to 2.490 you will never have any feed problems, and will not have to trim them as often as i do.