Tolerances

[Roooster_11]

When is it good enough? I'm new to reloading and I was reloading some .308 last night, and I don't have the absolute top of the line equipment, but I have good equipment. Well, it seems the best I could get when trimming cases was about +/- .005, and COL was about +/- .003. For really trying to tighten up groups, is this acceptable, or should I expect .000?

 

[cmillard]

the variances in your OAL is more than likely from differences in bullet dimensions. get yourself a comparator and sort by bearing surface length and your OAL differences will be much smaller.

 

[necchi]

For "new too it" that's pretty good. Don't worry, as you gain experiance your techniques will become improved and you'll begin to gain the "finese" that tightens things up.

You'll get many varied opinion, and it depends on what your loading for. Off the shelf hunters or custom bench guns,,, Those BR guy's can be in a whole nuther world ???

Just don't get stuck,, keep reading,, keep learning,, and most of all keep it safe and fun ;D

 

[Greg110]

What necchi said. PLUS dont forget about the effects of shooting technique and bench equipment!

 

[mikecr]

Neither seems a 'problem', but where are your errors coming from?

 

[lynn]

I may be reading your numbers wrong but +/_0.005 is 0.010 on your trim length and that is quite large.If you still have primers in your cases that may also affect your numbers.You want the comparator that mounts to your caliper with a hole were the primer seats so it doesn't influence your measurements.
Lynn

 

[Roooster_11]

I'll check into a comparator. Mike, I think I may need a different trimmer, I have an older Lyman and i can't seem to trim my cases to the same length.

 

[JaxCatm]

I am sort of in the same boat with reloading. New and still learning the game. When I first started my loads were all over the place. I saved some money and purchased good presses, Forster dies and a forester trimmer. After directing my energy towards getting each step in the process right from start to finish it is starting to pay off. Get yourself a Wilson case gauge to help out with setting the sizing die. The Forster trimmer is very simple and accurate just be patient and work with it. One other word of advice get gauge to check how concentric your loaded rounds are. Read a lot and try to make a check list of potential problems then start working to eliminate those problems one at a time. I'm not the most mechanically gifted person in the world and I don't know tons about reloading or rifles. But by starting with a checklist of potential problems and solving them one at a time I am now producing very good ammo that works for my rifle. I basically started from step one of sizing and depriming worked that until everything was ironed out and moved to the next step then so on. Yes I spent a ton of time at the bench and ruined some brass but I learned a hell of a lot in the process.

 

[Roooster_11]

Lynn, sorry about the confussion. I wrote my numbers wrong. What I actually meant was that I'm getting differences up to .005. Some are .003, .002, with the worst being up to .005.

 

[potatoe]

Lynn, sorry about the confussion. I wrote my numbers wrong. What I actually meant was that I'm getting differences up to .005. Some are .003, .002, with the worst being up to .005.

Are the differences .005 shorter of your normal case length? If so there for awhile I was fighting pretty much the same thing. I (using a forster original case trimmer) found that I just had to take more time and caution. Even though I have my set screw tight, if I pushed hard enough I could over trim the cases, also I measure before I start cutting, to get an idea of how much should be coming off. And slowly I trim, measure, trim, etc. thats been the best way I found to get them to be consistent with this trimmer. Also make sure you wipe of the case mouth, the shavings can give you a little variance.

 

[necchi]

Well said JaxCatm, well said indeed.

I'm sure many did that very same thing, I know I did. Anxious to get started, somewhat over confident from at least some reading, etc,,,
Then the first "groups" aren't turning into those cloveleaf's you where expecting,,

, What's going on here ? Am I doing this right?

Then ya slow down, "study" instead of light reading the books you may already have, pick up some more gear or replace the stuff you bought in haste, find a local mentor or trusted shop where questions can be answered.
This site is one of the GREATS for the Novice thru Expert levels,

This thread is a good example, Rooster is doing just fine, and will do better because of questions asked. It's all part of a learning curve that at least in my case, I hope goes on for a long time. I hope to keep learning and improving,,

 

[lynn]

Rooter11
I didn't see which trimmer you were using but as alot of the other posters are mentioning it here is how I would trim with it.
When you slide the case into the clamping collet make sure you push the alignment mandrel into the cases mouth and hold it firmly.By doing this one simple step you are making sure the the casehead is all the way against the collet and not 0.002 off.
I don't like/use the rotating section at all.It is the part that feeds the case into the trimmer.
I just set the set screw so it cleans up my shortest case and trim all of my brass to that length.When you hear the trimmer start squeaking you are very close.The squeaking is caused by light friction meaning the major trimming is all over.
I use a very expensive $9 Harbor Freight 6 inch digital caliper and measure each piece of brass.If one comes out too long I re-trim it.
You absolutely have to remove your spent primers before trimming your brass.If you don't you'll get bad numbers as the primers will hold the casehead away from the collet.
Lynn

 

[farmerjohn]

HI NEIGHBOR, I'VE FOUND THAT SOMETIMES YOU CAN GET "HUNG-UP" ON NUMBERS. TO PUT THINGS IN PERSPECTIVE, AN OLD MACHINIST TOOL IS A HUMAN HAIR, MOST ARE .003 IN DIA. GOOD SHOOTING

 

[Roooster_11]

Thanks for all of the good advise guys. I was definitely locking down the collet before putting the the mandrel to the case. I will give that a try, also I see that Lee makes a cutter with an attachment that goes into the case and stops at the flash hole....this seems like it would work very good and not allow you to trim too short and stop your trimming at the same point everytime. Anyone have experience with this product?

 

[RJinTexas]

Buy yourself a new Sinclair/Wilson SS Ultimate Trimmer #05-6200. The Micrometer head allows you to adjust in increments of .001 and reads in actual case length making it the easiest to work with and gives you identical trim lengths for every case. It cut 2/3 of the time off of the time it was taking me to trim my cases and they're spot on.

RJ

 

[necchi]

I see that Lee makes a cutter with an attachment that goes into the case and stops at the flash hole....this seems like it would work very good and not allow you to trim too short and stop your trimming at the same point everytime. Anyone have experience with this product?

Oh Ya! ;D
The Lee sytem works great! No Fuss, No Muss, The Same Every time. It's Too easy and Too affordable to not use.
It eliminates the "I hate Trimming" you hear so many say after they've wrestled with all the adjustments.
I'd recomend the "Zip Trim" tool also. Less hastle than the drill attachment.