Trim To Length Question

[MoreIsLess]

I just finally got the last of my reloading equipment from UPS today, everything except the bullets (details, details). I have Lymans 49th edition loading manual. In looking at the specifications for .45 ACP, the manual says the trim to length is .888" but the drawing provided shows a length of .898. Why are they difference and how much leeway is acceptable.

 

[Miata Mike]

Most people including myself do not trim .45acp. Not sure why the difference.

 

[Josh45]

I don't know anyone who trims .45ACP brass or any other handgun caliber for that matter. Don't worry about it tho, Load em to the O.A.L shown with your choice of powder and your good to go.

 

[Sunray]

Sounds like a misprint. My old Lyman book gives .895". .898" is the nominal max case length. However, as mentioned, .45's rarely need trimming.

 

[Jeff H]

the manual says the trim to length is .888" but the drawing provided shows a length of .898

The drawing is max length. Trim length is generally about .01 shorter. For pistol brass, I wouldn't worry about it. I don't know anyone who actually trims 45 brass.

 

[Hondo 60]

In Lyman's 49th edition the "trim to" length is always .010" less than stated case length.

 

[Walkalong]

I have never trimmed a .45 ACP case.

 

[Mal H]

Nor have I. They will split before they need trimming. Measuring .45 ACP cases (and most handgun cases for that matter) for over-max-length is a waste of time for 99.99% of all shooters.

 

[highlander 5]

99% of pistol/revolver doesn't need to be trimmed. shoot them till they split or you loose them.

 

[gamestalker]

The longer length is maximum and the shorter length is the trim too length. So when the brass gets to .898" it's time to trim down to .888". Though many don't trim certain catridges, usually the AL one's, it is at least advisable to check them from time to time so they don't get excessively beyond the maximum as established by SAAMI, I do.
Regarding such cases as the .45 ACP, .40, 9mm and a host of other AL straight walled cases, head space is maintained at the mouth which is why trimming is elemental in maintaining proper head space margins. Head space is a critical element of all firearms, and if it becomes excessive bad things begin to happen.
As time consuming as it is to trim brass, and it is, it is all part of the correct and established process of for reloading as has been clearly established by SAAMI. In my opinion, if trimming were unecessary and just a great big waste of time, none of my reloading manuals wouldn't include the process or even mention it, especially with a SAAMI specification by which to maintain.

 

[dave from mesa]

Never have trimmed 45acp brass. Come to think about it I've never measured them to see if they need to be trimmed. Wouldn't do it anyway.

 

[icanthitabarn]

I am new to reloading and trim almost everything. If consistency is the goal, then why skip trimming? This way, the case is always in the same place with regards to the breechface. I trim to .890 for SWC and .888 for RNL. Done once, they don't seem to change length at all. The cases are very inconsistent, in most instances and vary by huge amounts. To me, .880-.900 is a huge amount.

 

[soloban]

+1 dont trim 9mm or 45ACP. Don't even bother cleaning the primer pocket either.

 

[Hondo 60]

+1 dont trim 9mm or 45ACP. Don't even bother cleaning the primer pocket either.

+ anudder.