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Discussion Starter · #1 ·
What do you reloading aficionados trim your cases to when necessary?

My Hornady manual includes a case trim length for each caliber which is on average 0.01 lower than the SAAMI max length but my Nosler manual shows no such thing...I've been using the Hornady trim length and frequently get inconsistencies during the trimming phase. Any trimming tips would be appreciated.

As I move towards neck/bump sizing instead of full length sizing to help minimize case wear I'm trying to identify good trim/prep practices.

Another ? Is that if I bump the shoulder back by 0.02 it will also move the case neck by that amount correct? So in theory if the case is at 2.32 before firing it should be the same after a firing then bumping back correct?

I have ordered a case comparator and bullet comparator so I can start measuring my loads that way instead of using only the C.O.A.L.

All this is driven by a .270 that seems to have overly generous headspace, inconsistent accuracy and that appears to be wearing out brass at a high rate.
 

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What do you reloading aficionados trim your cases to when necessary?

My Hornady manual includes a case trim length for each caliber which is on average 0.01 lower than the SAAMI max length but my Nosler manual shows no such thing...I've been using the Hornady trim length and frequently get inconsistencies during the trimming phase. Any trimming tips would be appreciated. You only need to trim to a length that will function in your gun's chamber. Try to identify what that length is, then trim to that length, or whatever length your shortest case is that is below that number. Trimming all cases to the same length is most important.

As I move towards neck/bump sizing instead of full length sizing to help minimize case wear I'm trying to identify good trim/prep practices.

Another ? Is that if I bump the shoulder back by 0.02 it will also move the case neck by that amount correct? So in theory if the case is at 2.32 before firing it should be the same after a firing then bumping back correct?Not correct. Cases actually become longer after sizing many times. This is why you always size, then trim, then chamfer.

I have ordered a case comparator and bullet comparator so I can start measuring my loads that way instead of using only the C.O.A.L.

All this is driven by a .270 that seems to have overly generous headspace, inconsistent accuracy and that appears to be wearing out brass at a high rate.
If you are hand loading for a bolt action rifle and don't plan on sharing rounds between rifles, I would size and trim as little as possible to allow the cases to function in your specific gun.
 

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Discussion Starter · #3 ·
"You only need to trim to a length that will function in your gun's chamber. Try to identify what that length is, then trim to that length, or whatever length your shortest case is that is below that number. Trimming all cases to the same length is most important."

Any suggestions on how I determine this? Do I make a dummy round trimmed to SAAMI max specs then work backwards (shorter) from there? Or can I chamber JUST the case without projectile and work backwards trimming by 0.001 until it chambers well?

What are the chances that a once fired case will provide me this info if measured? What if my chamber allows a case longer than the listed max spec, is that a bad thing?

I have 3 different .270 bolt guns but plan to use loads developed for each solely/specifically.
 

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I've never really noticed an accuracy change from trimmed to length brass and brass that has grown over a few reloadings. I know it has an effect, neck tension, chamber binding and whatnot... but none of my rifles seem to care about it. I trim it when it gets excessive.

I use those simple cheap "goof-proof" lee case cutters. You can zip through a ton of brass soooo fast. Seems to give pretty consistent case lengths too. Very economical cutters for sure.


-DallanC
 

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Discussion Starter · #5 ·
I've never really noticed an accuracy change from trimmed to length brass and brass that has grown over a few reloadings. I know it has an effect, neck tension, chamber binding and whatnot... but none of my rifles seem to care about it. I trim it when it gets excessive.

I use those simple cheap "goof-proof" lee case cutters. You can zip through a ton of brass soooo fast. Seems to give pretty consistent case lengths too. Very economical cutters for sure.

-DallanC
What do you mean by "Trimmed to length" brass? As I mentioned, Hornady lists a test fired trim length but Nosler only shows a diagram of the SAAMI specs but doe not specify what they trimmed to during their testing.

So far, I've been trimming to the Hornady list length then reloading and as long as it hasn't grown past the SAAMI max, reloading them again. This poses an issue if the brass does not grow consistently across the batch because you end up with brass of different lengths.
 

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Trimmed to the SAMI spec for overall cartridge length.

Everytime you fire a cartridge, the brass flows forward as the case stretches. Upon reloading, typically all but neck sizing sets the shoulder back to SAMI specs. There isnt a way for a die to return the neck growth back to SAMI spec with regards to overall cartridge length, hence is must be trimmed (and btw, your cartridge gets thinner on the sides down near the case head, so watch for case separation signs there in brass thats been reloaded alot).

Lee case trimmers (the ones I use), the mandrel itself is already made to SAMI spec, so there really isnt even any measuring. You chuck the case into the base (which is in a drill), insert the mandrel / cutter in the neck and give it a quick spin. Anything longer than SAMI spec is cut off. Its really very fool proof... and faaasssssttttttt!


-DallanC
 

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This thing is base / cutter for $8, stick base in a power drill:


You get different mandrels for other calibers. You can never insert a mandrel "too far" as it spaces itself off the primer hole.

-DallanC
 

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Discussion Starter · #8 · (Edited)
Thanks for the replies DallanC!

I'm aware of the case stretch and incipient case head separation that can happen when brass becomes thin near the base. That is one of the reasons I want to start only bumping the shoulders back enough to chamber properly instead of FL sizing everything.

I have a ton of .270 brass that I sifted through this weekend, feeling each one inside with a bent paperclip to check for signs of the dreaded separation...I only threw away about 10 pieces, even cut one open as a cross section to see the thinning in person. Turns out it wasn't hardly even noticeable although I could feel a ridge on the case exterior with my finger.

My confusion really stems from the lack of definite information provided in my manuals. The SAAMI COAL is a measurement from the base to the tip of the projectile once fully reloaded, included in that are the measurements for the individual components. However, SAAMI specs also allow for some flexibility in the manufacturing process so there is both a high and a low end of each tolerance.

I've been using a Hornady LNL Case Trimmer with a drill to speed up the process which is great but I still get variances in case length and cannot seem to adjust it by small enough amounts to get every case exactly the same, every time and when they're trimmed, I can't help but feel the reaming process removes additional material which further changes the case length.

I will look into the trimmer you've mentioned and see how that goes...does having a deburred flash hole affect the cutting depth at all or is the mandrel set up to accommodate the reamed interior flash hole?
 

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Mandrel spaces off the inside of the case, it has a pilot that goes through the primer hole... so deburred holes wont affect it. There are some snazzy trimmers out there, not saying this one is the best... but its been good for me and fits my budget.


-DallanC
 

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I like to FL resize and trim to the "trim to length" after every firing. I know its not needed and may age my brass a little quicker but I like consistency. As for the trimming process, I use my forster trimmer and their 3in1 head which trims, chamfers, deburrs each brass in about 3-5 seconds with the drill attachment. http://ads.midwayusa.com/product/142441/forster-original-power-case-trimmer-3-in-1-case-mouth-cutter-carbide-30-caliber-308-diameter?cm_mmc=pf_ci_google-_-Reloading+-+Metallic+Reloading+Equipment+%28Not+Presses%29-_-Forster-_-142441&gclid=CLT81N33rswCFYKBaQodbr4Now
 

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I FL size my 6mm rem but neck size my 300 wm. I started off neck sizing both but couldn't get consistent neck tension on my 6mm; the die had issues. Switched to FL on my 6mm and at my skill level and rifle limitations, didn't notice any degradation in accuracy. I neck size the WM to hopefully extend brass life. I'm on reload #5 with some of the brass so I guess I'll see. I do notice that I don't trim off as much on the WM as the 6mm in spite of running it at a higher pressure.

As for trimming, I also use the lee mandrel system. It's really about as close to fool proof as you can get. I started out with it for cost and have never seen a reason to switch. If you wanted to trim slightly below SAAMI specs, you could always file a bit off the end of the mandrel and get to where you want.
 

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Discussion Starter · #12 ·
I like to FL resize and trim to the "trim to length" after every firing. I know its not needed and may age my brass a little quicker but I like consistency. As for the trimming process, I use my forster trimmer and their 3in1 head which trims, chamfers, deburrs each brass in about 3-5 seconds with the drill attachment. http://ads.midwayusa.com/product/142441/forster-original-power-case-trimmer-3-in-1-case-mouth-cutter-carbide-30-caliber-308-diameter?cm_mmc=pf_ci_google-_-Reloading+-+Metallic+Reloading+Equipment+%28Not+Presses%29-_-Forster-_-142441&gclid=CLT81N33rswCFYKBaQodbr4Now
$64 for each and every caliber would be well above my desired price range.

I like the idea of the Powered Lee Deluxe system that fits in the press, trims and chamfers all at once and is pretty inexpensive. I already have an RCBS case prep center though and would hate to make it obsolete by no longer needing the chamfering tools...I suppose I could sell it second hand to pay for the Lee system...or to put the money towards an awesome RCBS ChargeMaster (I'm already growing weary of trickling every round one at a time on my 5-0-2 scale)
 

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I use the RCBS Trim Pro Power Case Trimmer.

RCBS has discontinued the device, a good thing.

.
 
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