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Thread: Case trimming?

  1. #1
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    Default Case trimming?

    Hey after starting my last thread on Neck Sizing it got me thinking How many of you guys trim after every firing? I do and I always trim to "Trim Length."

    As an example 204 Ruger:
    Max Case Length: 1.850
    Case Trim Lentgh: 1.840

    So if I trim after every firing would it be a good idea'r or just a waste of Brain cells to maybe just trim them to... say 1.845 to give me a lil' bit longer neck? I'm loading 35gr Berger FB HP's and there is no way in H3LL I'm going to get them seated to a max COAL of 2.260 and still maintain .204 of the bullet seated. I hope this makes sense??? I'm just trying some things to see what type of accuracy I can ring out of this ultra light weight Ruger, and am wondering if this would help me get a tiny bit closer to those lands.

    Thanks, Jake

  2. #2
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    Well it isn't done just because it is done because the cases grow in length and need trimming. If you full length resize they tend to grow a few thousandths every shot and will be at the max length the next shot so they need trimming. The max brass length is because that is the minumum chamber length and if they exceed that length they can be jamming into the throat (the part where the bullet rests and it is .001" to .002" over bullet diameter, too small for the case diameter) of the chamber. So trouble would await if we let a case get longer than max . No damage from being too short but just an unnecessary step if the case only grows about .001" or .002" every shot. If you do not crimp it is not a critical dimension so any where within the trim length to the max brass length is ok.

    I trim at the .005" level meaning if cases are within .005" of each other and about .005 less than max, I'm good to go. With your 204 Ruger it would be 1.845" ish for all cases say 1.842" to 1.847" I'd shoot and trim next time. Of course for the utmost in accuracy every case should weigh the same and be the same length and have the same size flash hole and the same neck wall thickness. This is the brass prep for the gnat's butt precision that we sometimes strive for.
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  3. #3
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    Default Thanks Murphy!

    Quote Originally Posted by Murphy View Post
    Well it isn't done just because it is done because the cases grow in length and need trimming. If you full length resize they tend to grow a few thousandths every shot and will be at the max length the next shot so they need trimming. The max brass length is because that is the minumum chamber length and if they exceed that length they can be jamming into the throat (the part where the bullet rests and it is .001" to .002" over bullet diameter, too small for the case diameter) of the chamber. So trouble would await if we let a case get longer than max . No damage from being too short but just an unnecessary step if the case only grows about .001" or .002" every shot. If you do not crimp it is not a critical dimension so any where within the trim length to the max brass length is ok.

    I trim at the .005" level meaning if cases are within .005" of each other and about .005 less than max, I'm good to go. With your 204 Ruger it would be 1.845" ish for all cases say 1.842" to 1.847" I'd shoot and trim next time. Of course for the utmost in accuracy every case should weigh the same and be the same length and have the same size flash hole and the same neck wall thickness. This is the brass prep for the gnat's butt precision that we sometimes strive for.
    Leaving my case's in the middle of the trim to length-to max length ie 1.845 is exactly what I was talking about. Since I trim every time and hand weigh all charges I figured it couldn't really hurt. I already uniform my flash holes and primer pockets but I think thats as "gnat's butt" as I'll be getting

  4. #4
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    Default

    i trim when my longest case in a batch is about .005 to max legnth.

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    This case trimming thing is where the Sinclair Chamber Length Gage Insert comes in handy. You use it to measure your bolt action rifle's OAL chamber length(inserts are caliber specific)then subtract .024" and you have the max case length for THAT rifle. If your wanting to possibly increase neck length this is one way to do it.

    til later

  6. #6
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    Quote Originally Posted by CZ_IN_AK View Post
    Hey after starting my last thread on Neck Sizing it got me thinking How many of you guys trim after every firing? I do and I always trim to "Trim Length."

    As an example 204 Ruger:
    Max Case Length: 1.850
    Case Trim Lentgh: 1.840

    So if I trim after every firing would it be a good idea'r or just a waste of Brain cells to maybe just trim them to... say 1.845 to give me a lil' bit longer neck? I'm loading 35gr Berger FB HP's and there is no way in H3LL I'm going to get them seated to a max COAL of 2.260 and still maintain .204 of the bullet seated. I hope this makes sense??? I'm just trying some things to see what type of accuracy I can ring out of this ultra light weight Ruger, and am wondering if this would help me get a tiny bit closer to those lands.

    Thanks, Jake
    This is where a custom chamber would be good. You could have a barrel chambered and throated to place the 35 grain Bergers seated .204" into the trimmed case length and have them .006" (or some other distance) off the lands. You could also adjust other dimensions of the chamber, that's why they call it custom, all it takes is money. Of course then you would have to have custom dies made......you see where this is going.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



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