Case Trimming

forgive me if I should know the answer to this, but i am still green. I have recently started reloading for my .270 win and .223 with fabulous results accuracy wise. I have a question about trimming when the cases get a little over max length. In the reloading books, it says the max case length for .270 win is 2.540 with a trim to length of 2.530. I have about 30 rounds of brass that I have shot twice, and about half of it is right at the 2.540 mark with the other half being between 2.541 and 2.548. The brass that's a little over length will feed fine through my rifle, but I wanted to know if Its ok to load it on up at a little over length, or do I need to wait on getting a trimmer before I do?

thanks in advance!

I think, but dont quote me, that the recomended "MAX" length is about .010 less than the actual MAX length of a standard chamber usually. Like you said, you have soem thats over the reccomended max that still feeds. I would imagine if they get to .010 over that max youll start to see problems.

Before I new anything about neck trimming I reloaded brass many times without ever even thinking about the case length with no problems but now that I know I try to keep it all under the reccomended max if for no other reason than to make it all consistant.

SO, a little longer MAY work just fine. A little shorter WILL DEFINATELY work just fine. Better safe than sorry. I think I'd rather do a little trimming and be consistant and SURE it would work than one of these days getting too long and having a problem or best case only having to pull a bunch of bullets and redo it again.

The "actual" chamber lengths are usually about .020 over the Max trim length.
My BR brass lists a Max trim length of 1.560 and the "Actual Measured" length of the chambers are 1.584 to 1.585 so I know I have a long way over Max before I need to start thinking about trimming.
And it depends a lot on the type of resizing dies you use. Full length dies with the expander ball will pull the neck longer compared to shoulder bump/bushing dies.
On 99.99% of all my brass, I use shoulder bump bushing dies and my brass doesn't grow. Bushings size the neck, shoulders get bumped back maybe .001 to .0015 and size with a body die if the case starts getting snug in the chamber.
(maybe every 5th. or 6th. firing?) No trimming needed or very seldom. 8)

thanks for the replies. Another question....i have the rcbs 2 piece die for .270 and a lee 2 piece for .223. Would these be full length resizing dies or just neck sizing?

the dies should say FL or Neck on them.

T-bird, You more than likely have the standard "2 die set" consisting of F/L size die & bullet seater die. If you're getting accuracy suitable for your purpose don't change a thing. Otherwise, the hopelessly addicted accuracy buffs posting here will have you buying a mountain of gadgets to "improve" groups. Not that this is a bad thing, but it can get REAL expensive. ::)

Best to get use to what you have and "really" learn how to use it. Won't be too long till you'll be wanting the "hoplessly addicted accuracy stuff". ;) And NO, that isn't a bad thing, just more $$. 8)

The issue with over-length brass has nothing to do with feeding, but headspace/pressures. If you have brass to long, it can bottom-out on the end of the chamber, and "crimp" into the bullet. Best case senario is damaged bullet jacket, and poor accuracy. Worst case is high pressures, stuck bolts, dead monkeys,etc...
If you don't want to fool with setting up a trimmer for one case, then switch for another; buy Lee trimmers. They are cheap, retarded simple, and no setup.

Quote:

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Originally Posted by darkker

The issue with over-length brass has nothing to do with feeding, but headspace/pressures. If you have brass to long, it can bottom-out on the end of the chamber, and "crimp" into the bullet. Best case senario is damaged bullet jacket, and poor accuracy. Worst case is high pressures, stuck bolts, dead monkeys,etc...
If you don't want to fool with setting up a trimmer for one case, then switch for another; buy Lee trimmers. They are cheap, retarded simple, and no setup.

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Probably why I have had such great luck with them. They work and are very, very simple as well as cheap.

If you want to get the most life out of your brass you need to seperate the FL sizing and neck sizing step. The pull through mandrel type works the brass a lot and hardens it. I use a Lee collet neck sizer and a Redding body die. Brass hasn't grown enough to trim since I started using them. If you want a little more neck tension you can reduce the diameter of the neck collet by chicking it in a drill and hitting with a file or sandpaper. I do that rather than crimp and have never had an issue.

Dolomite

Another option is to actually measure your chamber length. Then when your brass grows to within 0.010" of your chamber length. It's time to trim. You'll know the actual length of your chamber and won't spend a lot of time needlessly trimming your brass.

You can order a Sinclair Chamber Length Gage Insert (top of photo). Just cut down the neck on a case, insert gage, feed into correctly headspaced barrel and measure the actual chamber length.

The case at the bottom of the photo is what others call "A poor man's" chamber gage. Neck size a case trimmed to the minimum spec., cut a ring from the neck, place tightly on a bullet, feed into the chamber and measure the length. Just make sure the bullet is not contacting the lands before the ring contacts the end of the chamber.

[img width=600 height=450]http://i266.photobucket.com/albums/ii276/jpdown/PICT0010.jpg[/img]

Also important is that all of the cases are the same length. Varying neck tension (due to inconsistent lengths) can really mess up your groups.