CASE TRIMMING QUESTION

[JPS]

My book says max.case length is 2.620 and trim length is 2.610.What is the tolerance if it is a little over or a little shorter?I mean if it is a little over 2.620 is it ok?It is a .300win.

[Deleted User]

[Deleted by Admins]

[coyoteseeker]

most data books listings are on the low side or in this case the short side.if your a little over the max length its not going to hurt anything.they do this becouse the longer the case the closer the bullet is to the lands and groves,the closer the bullet the higher the pressure.unless you can monitor pressure increases and other high tech aspects of reloading its a good idea to stay within the limmits of the guide books.the most important thing is to pick a length(within the limmits) and keep all your cases at that length.

[handloader1]

I trim my cases to the Min. spec. everytime I load. Good luck.

[Vapodog]

JPS, I've been handloading for 40+ years and for everything from .222 to .375 H&H. There will definitely be folks opposed to what I'm going to say but it's worked for me for a long time.

Your loading manual gives a tolerance......and it must be understood that "too long" a case can actually pinch the bullet if driven to the foreward end of the chamber. The camming action of a bolt action rifle is very powerful and a bullet so wedged by the end of the case can very much cause escallated pressures. This can be a very serious problem!!! A couple of thousandths may not cause a problem but you don't know how long your chamber is.....so I say never load a case longer than the published spec.

Now for too short a case.......welllllll..... practally no problem unless we remove most of the case neck!! I always measure the case after resizing and because I hate trimming cases, I trim them a full .030 under the max length specified. By doing this, I'm not likely going to ever have to trim that case again in it's lifetime. I've done this with several varmint cartridges and have never suffered any kind of problem ever.....and I certainly have never found a loss of accuracy from cutting cases .020 less than what the manuals call for.

If you believe you need to crimp your bullets then this may be a bad decision to trim so far back but in all these years, the only place I've found crimping bullets is necessary is with very powerful handgun loads and some loads going into tubular magazines.

If you follow the manual you should be fine always, but if you've trimmed some a little too short, I'd not be afraid of them in the least. Good shooting to you!!!

[stubblejumper]

Vapodog hit it on the head.If your cases are too long they could jam at the end of the chamber and cause very high pressures.Trim length does not change you bullet position in relation to the lands.That is controlled by the setting on your seating die.

I used to trim every reload. But I have saw premature case head separation when i did that on some calibers like my 300RUM. But with that said, why take a chance of super high pressures. Why not just follow the directions, trim to min. length, shoot two or three times until it reaches max again, and then trim again. I personally believe that consistent case lengths help accuracy.

[Vapodog]

Bigcountry, thanks for reminding me, if the cartridge is one that "headspaces" on the forward end of the case (such as the .30 M-1 Carbine and sorry, I don't know about the .300RUM) then cartridge length becomes critical!!!

I'm a big fan of the L. E. Wilson case trimmer!! BTW

[thndrchiken]

I usually measure about 5 to 10 cases out of the batch of brass I'm prepping, if I feel it's too long I'll trim the entire batch using a Lee cases length gauge. Puts it to SAAMI and I won't have to trim again for another 2 loadings. As far a crimps go, I use a moderate to heavy crimp on anything going in a tubular magazine and a light to moderate crimp on everything else with a cannelure ring. That seems to work for me.

[Vapodog]

while it might work for some folks, I'd not recommend a statistical sampling method for case lengths.....I'd strongly recommend a 100% inspection plan!!