Case trim length

[West Calamus]

Does every one trim back to minimum case length when trimming cases? Is there any advantage to only trimming too half way between Maximum and minimum case length?

 

[Savage 12BVSS]

I always take them back to trim length and call it good, they need to be done soon enough anyway.

 

[Rick Richard]

Yep. I do this to ensure consistency in neck tension for all the brass. However, I have found some brass brands (Lapua) to be all the same in length and I just leave it there.

 

[Bang4theBuck]

When I take the time to trim, I trim back to min. That said, one of the attributes of many of the highly accurate cartridges is a long neck. Im not sure that the difference between trimming partially and trimming fully (.005-.010") is going to be a huge accuracy contributor, but I'm sure the benchrest guys might argue that point.

 

[mwkelso]

I trim every time to maintain consistency. After all, that is the main component to reloading, right?
I trim my cases 0.010" shorter than maximum. That's how my first trim chart suggested I trim, and haven't found any reason to do otherwise.

 

[rammac]

The advantage to trimming to the long end of the spec is that you can get a wee bit more powder behind the bullet.

 

[dok7mm]

It's a good idea to measure your actual chamber case length first and trim cases to .010" short of that measurement.

I've found I get more carbon ring buildup with shorter cases, so I started trimming to .005" under my measured chamber length. I do have to take care that my cases are not over that .005".

It's fine to also use .010" under your chamber, to be safe. If your chamber and resizing die don't mesh well, you will be trimming more often.

 

[tnek13]

I set my Little Crow once and do all cases the same after each firing, and it is not min just enough to chamber reliably.

 

[PApa Black]

Does every one trim back to minimum case length when trimming cases? Is there any advantage to only trimming too half way between Maximum and minimum case length?

I trim to -.003" from Max in my 308s and 6.5CM. I find it makes a more accurate round.

 

[West Calamus]

Thx for all the responses guys. I did gather from all your responses that just be consistent and and have them all trimmed to the same length no matter the length you choose.

 

[AZShooter]

There are factory chambers with the end of the chamber being very long so that trimming isn't necessary for many firings or perhaps never during the life of the brass. Factory recommendations for trimming a case can leave a .050" to .070" gap between the end of the case and the actual length of the chamber! Unless you used a custom reamer and know the distance to the end of the chamber, it is good to know the distance for each rifle. I suggest that many cases are being trimmed unnecessarily.

Sinclair makes an end of chamber gauge:

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[ShtrRdy]

The advantage to trimming to the long end of the spec is that you can get a wee bit more powder behind the bullet.

I'm having trouble understanding how trim length affects powder capacity. Would you mind explaining that?

 

[J E Custom]

Sounds like there are many different approaches to trimming. In My loading book for each firearm, I have the actual neck chamber length of that firearm and prefer to trim .010 less than that dimension, as long as all of the cases clean up. I never take more than necessary and only enough to clean all the cases up. I also clean the chamber and bore often so I don't see the carbon problem that some see.

As stated in other post, I do this when my brass is new and gives me the best results. With minimum sizing, normally this is the only time I need to trim during the life of the case. generally I see very little case growth because of the sizing and the pressures I load to. A periodic check as you load is still prudent and recommended.

A dummy case in the die set is a good gauge to use when setting up your trimmer, and applying a blue die to the end of the gauge case and setting the cutter by turning it backwards will prevent you from removing any brass from the gauge case. This keeps the load very consistent unless you have to remove some of the case neck often and then thinning and neck tension may become the reason loads can change.

Also Most of the time, well sizes new cases with minimal head space will normally stay within .003 or .004 thousandths when fired the first time, and if you want to re trim then you could and start with uniform case neck lengths. After that, I rarely have to trim again.

J E CUSTOM

 

[BrentM]

Just get the Sinclair chamber tool and trim to your chamber. I rarely have to trim any of my cartridges using my actual chamber length.