Trim-to-length... how critical?

[mpthole]

I just got a Lyman trimmer and have been working on a batch of .308 brass. How critical is it to stay at or above the trim-to-length of 2.005? If I get some that are at 2.000 am I risking a kaboom?

FWIW, it seems like I get more consistent results when I use the hand crank versus the drill adapter.

 

[Kimber1911_06238]

Stick to the max case length in your reloading manual...any longer and it may fail to chamber correctly and risk increased chamber pressures. I like the hand crank just because I feel that i ahve better control...just my $0.02

 

[USSR]

How critical is it to stay at or above the trim-to-length of 2.005? If I get some that are at 2.000 am I risking a kaboom?

Trimming your brass shorter than the specified trim-to-length will not cause any problems at all. The actual length you trim them to is irrelevent, as long as they are all the same length and shorter than the specified maximum length. I typically trim mine to the same length as my shortest length case.

Don

 

[The Bushmaster]

If a rifle case gets too long it will start to enter the lede of the throat and this will cause the case mouth to be restricted causing a large increase in chamber pressure. You can tell when you have a problem when the loaded round chambers hard at the end of the bolt stroke. Keep your cases at or below manual specification as stated in above posts...

 

[mpthole]

Gotchya. That is kind of what I figured. This is a bunch of gunshow brass I picked up and when I measured a random sample, almost all were over the 2.014 max length, so I decided to just trim all of them.

Thanks again!

 

[Walkalong]

Too short might hurt accuracy, but too long can cause real problems like Bushmaster pointed out.

 

[scrat]

you should do a full size on them first


then trim to length as they could get longer after a full case sizing

 

[The Bushmaster]

Yup. Yup. Forgot about that...What scrat said...

 

[mpthole]

I've run everything through the full-length size die already. That's pretty much my standard when buying "once-fired" gunshow brass. These will most likely be used for plinking ammo or at the most, 3-gun matches in the heavy metal division. Minute of pie-plate is as accurate as I need to be for those. Of course, I may load some up for my bolt gun and see if it really affects MOA accuracy or not.

 

[TooTaxed]

I have found that virtually all fired rifle brass needs trimming, even .223. On the other hand, pistol brass rarely needs trimming, as long as maximum loads weren't used.

I've used a Forster manual trimmer for many years...but check out the Lee Zip Trimmer on the Lee website...a rather interesting and inexpensive innovation. You can also read the User Ratings on Midway...most good, some noting problems.

 

[HSMITH]

I usually trim a little short, then I get a couple more loadings out of them before trimming again. .005" short isn't going to hurt a thing.

 

[Bullet]

You could buy a chamber length gage and know your chamber length –

http://www.sinclairintl.com/cgi-bin/category.cgi?category=RESDTCL&item=G-308&type=store