Brass Trim Length

[Cort]

How do you determine the appropriate length to trim cases? Does each rifle has its own preferred length? Or, do you trim to the minimum, standard case length each time that trimming is required?

Thanks,

Cort

 

[RonAKA]

My theory for what it is worth is to let the brass grow to max length, and then trim it to that dimension every time you load. My 6BR Lapua brass came new at 1.555". My plan is to let it grow to 1.560" and then use a Lee trimmer to keep it there. I want all the neck I can get. The Lee is so fast and easy with no setup, that it takes little time.

Others who load a lot more rounds may select a range, and for example let it grow to 1.560 and then cut it back to 1.555. Will save you some time.

 

[jimbires]

sinclair makes a chamber length tool . you can measure the chamber length of your rifle . that will give you the true max case length for that rifle .

http://www.sinclairintl.com/.aspx/pid=32925/Product/Sinclair_Chamber_Length_Gage

 

[750k2]

I second the Sinclair tool - you will be surprised how long
your chamber really is - There is a lot of unneeded trimming.

 

[Shynloco]

Cort,
I pretty much go by whatever the Sierra Manual says for "Trim Length" because I use mostly Sierra bullets in several caliber. Now as my friend Ron AKA points out, he trims his Lapua brass for his 6mmbr to 1.555 whenever it "grows" longer. Since I first bought my Savage 6mmbr, a close friend who shoot Benchrest Competition suggested I trim my Lapua brass and keep it at 1.550. Now my rifle admittedly has a tight chamber, but after fireforming all my Lapua brass and trimming it to 1.555, I'm on my 11th reloads with that same brass and have only had to trim a very few casings perhaps once during all those reloads. And I remeasure each piece of brass after every shooting.
My suggestion to you would be to take a look at whatever manuals you have and check out the "trim length" for whatever caliber you are loading for. Beyond that, ask around with some of the experience and accomplished shooters to see what they do. But I also believe, if you are uncertain, go with what your manual indicates because the guys who write those manuals test everything they write about.

 

[Joe O]

+3 on the Sinclair chamber length gage.For about $7 you should have one for every caliber you have.I trim .010-.015 shorter than chamber length,depending on the cartridge.

 

[NorCalMikie]

The Sinclair Chamber Length Gauge (plug) is the way to go. Get one for every caliber you have. Example: I've got 2 different 6 BR barrels.
Max trim length on Lapua brass (by the book) is 1.560".
One chamber measures 1.580" and the other measures 1.584". That gives you lots of room before you "need" to trim. Set the trim length where "you" want it. Once you know the "actual chamber length", you can decide what length you want your brass. .010" to .015" short of actual chamber length would be a good.
If you shoulder bump .001" to .002" and neck size, your brass won't grow and will last much longer. Don't cut your brass unless you "need" to. JMHO, Mike.

 

[fdshuster]

The "trim to length" dimensions shown in the reloading manuals are "one-size-fits-all". If you're happy doing that, ( and most likely over trimming your brass), then by all means continue to do so, and you'll also be creating an even longer gap in front of the case mouth that will soon fill up with a ring of carbon. I've seen it with my borescope, so know what I'm talking about, not what "I think". I use the before mentioned Sinclair gauges for each of my rifles, record those lengths and trim accordingly, usually .010" shorter than actual chamber length. Some of my factory rifles have chamber lengths that are .040" longer than maximum case length.

 

[Preacher]

Franks dead on with that one size fits all remark... How can they possibly know how long your chamber is... you really need to check out what your's is and cut to that..
The Sinclair tool works very well, and a Hawkeye borescope in a opened up case will tell you where your at also... Most times a case needs no trimming at all especially in a factory chamber..