What to trim cases to?

[diego-ted]

Tikka 308. I measured my chamber with the Sinclair gauge that fits in the neck of the case, my chamber measured 2.048 Now I know the recommended case length is 2.005. Based on this info what length should I trim my cases to? How long should I let them grow before trimming?

Thx

Diego

 

[cstmwrks]

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[armorpl8chikn]

Re: What to trim cases to?

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

Buy one of these and you will know exactly when and how much to trim your cases.

 

[MinorDamage]

Re: What to trim cases to?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cstmwrks</div><div class="ubbcode-body">...guys who shoot <span style="font-size: 14pt"><span style="font-weight: bold">parma</span></span>...</div></div>

I ruv parma.

Josh

 

[turbo54]

Re: What to trim cases to?

Remember 2.805" is MINIMUM SAAMI. I like to leave them as long as I can.

I find lapua necks get uneven around 2.825, so that's my trim length. Most NATO cases I have arrive once fired at 2.830, so those also get trimmed to 2.825.

Perhaps one could argue that less neck length equals less tension and therefore more accuracy...who knows? Another argument is longer necks means less throat wear...?

I think the key is not jamming your case mouth into the throat. Provided that doesn't happen, I think your fine.

 

[MinorDamage]

Re: What to trim cases to?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">Remember 2.805" is MINIMUM SAAMI. I like to leave them as long as I can.

I find lapua necks get uneven around 2.825, so that's my trim length. Most NATO cases I have arrive once fired at 2.830, so those also get trimmed to 2.825.

Perhaps one could argue that less neck length equals less tension and therefore more accuracy...who knows? Another argument is longer necks means less throat wear...?

I think the key is not jamming your case mouth into the throat. Provided that doesn't happen, I think your fine. </div></div>

I think you mean max 2.015 and trim to 2.005.

Josh

 

[turbo54]

Re: What to trim cases to?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MinorDamage</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: turbo54</div><div class="ubbcode-body">Remember 2.805" is MINIMUM SAAMI. I like to leave them as long as I can.

I find lapua necks get uneven around 2.825, so that's my trim length. Most NATO cases I have arrive once fired at 2.830, so those also get trimmed to 2.825.

Perhaps one could argue that less neck length equals less tension and therefore more accuracy...who knows? Another argument is longer necks means less throat wear...?

I think the key is not jamming your case mouth into the throat. Provided that doesn't happen, I think your fine. </div></div>

I think you mean max 2.015 and trim to 2.005.

Josh </div></div>

Whoops! Sorry about the confusion guys!

Please subtract .800" from all dimensions I mentioned.

 

[Fuzzball]

Re: What to trim cases to?

"How long should I let them grow before trimming?"

Keep your cases shorter than the chamber. SAAMI does not set a minimum trim-to length.

 

[armorpl8chikn]

Re: What to trim cases to?

I can't believe no one called me on telling you to buy something you already had purchased. Admittedly I did not read your post simply the title.
The whole purpose of these case neck tools is to eliminate your need to trim until you get near YOUR chamber max length. If you have used one of these tools your trim length should be glaringly obvious, but let me get my spoon.
You MUST trim before you get to 2.048, hopefully you had figured that out at least. Now we need to decide what motivates you, do you load a lot or a little? If you load a lot then pick a number that will allow you to get several firings without trimming...lets say 2.024" or maybe just round it to 2.020" for a nice clean number. That will be your "trim to" length. Now you need to decide how close you will go to 2.048", to be on the safe side I would trim at 2.038". I run a lot closer on my cases but I have been at this a lot longer and I know how my cases grow each firing and my chambers and guns are custom.
Between those two numbers (2.020" and 2.038") you do nothing. Now if you are a glutton for punishment you can go to 2.038" and try to maintain that length and trim every firing but accuracy wise in my opinion it would be a waste of time. Keep em long but not too long and you don't have to trim every time you pull the trigger.

 

[diego-ted]

Re: What to trim cases to?

I think the case would disinagrate before it grew to 2.038!! So I guess there is no ideal lenght as long as they a shorter then the chamber?

Diego

 

[BobinNC]

Re: What to trim cases to?

Diego,

In terms of safety, shorter is better than longer. Nothing will get you in trouble faster, than a case that is too long for the chamber. There is no danger having a case 2.005 long in a 2.025 chamber. But you can run pressure problems by having a 2.035 case in a 2.025 chamber.

Of course you can measure and run them as long as the chamber, but then you really have to watch the growth, and be conscientious, and measure each case, every reload. Why bother, when you can cut'em short, and then be lazy. They will shoot well short or long.

Since I hate trimming cases, and then camfering and deburing them, I trim them back to minimum (for 308's 2.005"), when I trim. When they need a second trim, having grown to 2.015 or longer, I trim them, and put them into them recycle bin, meaning one more loading then out the door.

 

[armorpl8chikn]

Re: What to trim cases to?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: diego-ted</div><div class="ubbcode-body">I think the case would disinagrate before it grew to 2.038!! So I guess there is no ideal lenght as long as they a shorter then the chamber?

Diego </div></div>
Now you are getting the picture. I do not push my loads for competition and I know how to set up FL dies for maximum case life so I tend to let my cases grow. I do an initial clean up trim and like Bob I will end up throwing them out with primer pocket issues before they need trimming again.
If you set up your dies correctly for minimum bump you will probably never need to trim again with .043" extra beyond 2.005". My 6BR is another story. I tend to run them a bit hotter but I don't have as much extra length in the neck area either. It is also Lapua brass so I will get many more loadings than the dukes mix of 223 brass that I currently run. I have some Lapua brass for the 223 but have yet put it in service.

 

[18Echo]

Re: What to trim cases to?

call me crazy but to keep things simple I trim to 2.000 and call it good.