Trimming help/information/advice

[kalielkslayer]

So I’m new to case trimming and have some questions, and confessions.

I bought 2,200 .223 range brass, mixed headstamps. I tumbled em all shiny clean and was in the market for a case trimmer. During that search, I was gifted 3,500 more .223, same headstamp brass. More cleaning including sizing/depriming/another wash the get the lube off and primer pockets clean on about 1,200 of them. That’s the back story.

Now my confession. I couldn’t find a motorized case trimmer anywhere. So I overpaid for one on EBay. While waiting for it to arrive I found one on a shelf, and one online.

New to me case trimmer arrives. Everything there, looks like new with machine oil on some of the parts. (Should mention it’s the Franklin Arsenal). I start getting it set up, and trimming. I struggled for consistency. I was striving for 1.175. My cases measured 1.1748-1.1756 I wasn’t good with .008 variance. I posted on here, but a typo on length made my question weird.

So I ordered a new cutter (this was 1st week of March). Delivery date of 5/08/2021. With all that brass to trim, I got impatient and ordered a “new” Franklin Arsenal case trimmer (I know).

We got great weather so I left the reloading room to complete a few outdoor projects.

Today, with rain and snow, I set up the new trimmer. And was disappointed! Better at between 1.1748 and 1.1751 But why can’t I cut 2 pieces of brass the exact same length??? And it’s taking me 45-60 seconds to trim from around 1.1762 to 1.175. Is this normal?

If what I’m doing lengthwise is acceptable, I just want to know. PS: I am twisting the brass 90 degrees after it gets done cutting.

If 45-60 seconds per piece is normal, I just need to know that.

Straighten me out, someone.

 

[peels]

The trimmer that you are using is using the shoulder to locate and determine the trim length. If you are trimming mixed head stamp brass, it is quite possible for datum differences from shoulder to the brass base due to differences in brass hardness and springback. Even same headstamp brass will have some variability. That variation translates directly to trim length variation.

Another thing that will affect trim length is hand pressure when holding the brass against the trimmer. The more consistent you are, the more consistent the trim length reaults.

Lastly, it depends on your application for the brass. If this is meant for some AR plinking fun, I think what you are getting is quite acceptable. If for precision shooting, I recommend at least sort by head stamp and see if the consistency improves.

 

[NMexJim]

So I’m new to case trimming and have some questions, and confessions.

I bought 2,200 .223 range brass, mixed headstamps. I tumbled em all shiny clean and was in the market for a case trimmer. During that search, I was gifted 3,500 more .223, same headstamp brass. More cleaning including sizing/depriming/another wash the get the lube off and primer pockets clean on about 1,200 of them. That’s the back story.

Now my confession. I couldn’t find a motorized case trimmer anywhere. So I overpaid for one on EBay. While waiting for it to arrive I found one on a shelf, and one online.

New to me case trimmer arrives. Everything there, looks like new with machine oil on some of the parts. (Should mention it’s the Franklin Arsenal). I start getting it set up, and trimming. I struggled for consistency. I was striving for 1.175. My cases measured 1.1748-1.156. I wasn’t good with .008 variance. I posted on here, but a typo on length made my question weird.

So I ordered a new cutter (this was 1st week of March). Delivery date of 5/08/2021. With all that brass to trim, I got impatient and ordered a “new” Franklin Arsenal case trimmer (I know).

We got great weather so I left the reloading room to complete a few outdoor projects.

Today, with rain and snow, I set up the new trimmer. And was disappointed! Better at between 1.1748 and 1.151. But why can’t I cut 2 pieces of brass the exact same length??? And it’s taking me 45-60 seconds to trim from around 1.1762 to 1.175. Is this normal?

If what I’m doing lengthwise is acceptable, I just want to know. PS: I am twisting the brass 90 degrees after it gets done cutting.

If 45-60 seconds per piece is normal, I just need to know that.

Straighten me out, someone.

Once set-up, I don’t think it takes me longer than maybe 15 seconds and that’s with a Forster hand unit and a 1/4” electric screwdriver. Let the trimmer do the work and for sure you shouldn’t need a lot of pressure.

 

[kalielkslayer]

The trimmer that you are using is using the shoulder to locate and determine the trim length. If you are trimming mixed head stamp brass, it is quite possible for datum differences from shoulder to the brass base due to differences in brass hardness and springback. Even same headstamp brass will have some variability. That variation translates directly to trim length variation.

Another thing that will affect trim length is hand pressure when holding the brass against the trimmer. The more consistent you are, the more consistent the trim length reaults.

Lastly, it depends on your application for the brass. If this is meant for some AR plinking fun, I think what you are getting is quite acceptable. If for precision shooting, I recommend at least sort by head stamp and see if the consistency improves.

The cases I’m doing right now is all RP brass.

These cases are all for AR platform guns. Not expecting the accuracy of a bolt gun but trying to be as consistent as possible.

 

[Blue68f100]

Have you checked the sized brass with a case gauge or some means to see where the shoulder is before and after sizing? I think the differences your seeing is due to the shoulder begin in a different positions. I use the drill press cutters with the 3way cutter. I only vary about 0.002" max, mainly because I anneal the brass prior to sizing. In any case what your getting is acceptable for general shooting.

 

[243winxb]

Full length size brass first, before trimming.

What machine gun are you running, that all that brass is needed?

 

[edwardware]

These cases are all for AR platform guns. Not expecting the accuracy of a bolt gun but trying to be as consistent as possible.

Eight thou variation in trim length will not have a measurable effect of accuracy in an AR, or in a bolt gun until you're at least sub-MOA. Measure less, shoot more.

 

[kalielkslayer]

Have you checked the sized brass with a case gauge or some means to see where the shoulder is before and after sizing? I think the differences your seeing is due to the shoulder begin in a different positions. I use the drill press cutters with the 3way cutter. I only vary about 0.002" max, mainly because I anneal the brass prior to sizing. In any case what your getting is acceptable for general shooting.

No I haven’t.

 

[kalielkslayer]

Full length size brass first, before trimming.

What machine gun are you running, that all that brass is needed?

The cases I’m trimming have been full length sized/deprimed/tumbled again.

 

[entropy]

I use an RCBS trim die. Run 'em up in, flat file anything sticking up, and chamfer inside and out. Quick, easy, and cheaper than an electric one.

 

[mrawesome22-250]

The acceptable range per SAMMI is 1.730" to 1.760" case length for 223Rem. If they fall in that range, load 'em and shoot 'em.

As said, that trimmer uses the shoulder of the case as a reference point. Expect variations.

 

[PWC]

I trim by hand with a Lee trimmer. Length is determined by preset pin. I have never been faced with such a large lot nor sich a predigious task.

I get small variations; before you measure, carefully chamfer ID/OD, because there may be small "whiskers" that can affect your reading.

 

[AJC1]

If you are indexing off the shoulder you should be getting consistent neck length. If you index off the base of the case you should get constant case length. Trimming off the shoulder became popular because people neck turned and it allowed easy setup for those types of tools. It's funny that now bushing dies are popular but neck turning is less in favor.... makes no sense.

 

[cfullgraf]

Fire and reload the cases in your rifle and see if the varibility goes away.

The cases were probably fired in many different rifles and not all chambers are exactly the same. The sizing and shoulder set back could vary some case to case.

Just a thought.

 

[jonas66]

before you measure, carefully chamfer ID/OD, because there may be small "whiskers" that can affect your reading.

For a while I was getting odd variations in .223 cl that didn't always seem right.

Someone here once advised using a soft abrasive sponge to just barely swipe the case mouth over, after trimming and de-burring, but before measuring.

I use the 3M 'fine' grade all purpose large size wet/dry sanding sponge after trimming and a quick de-burr.
Then measure, (re-trim and repeat if necessary) then chamfer.

Those 'whiskers' of brass aren't always visible to my eyes but there's always a pile of them in front of the sponge when I'm done.

I use the Lee lock stud in a drill, mounted in my bench vise, and the Lee case length gauge and cutter handheld.

It took some practice, but I can almost always nail 1.750", with occasional variations.

It's satisfying to get exactly 1.750", but I usually accept anything from 1.7485" to 1.7515".

I load and shoot the longer or shorter also, they just get sorted into their own groups.

Oh- and time: The brass-cutting part of the trim takes about 4-5 seconds, the whole operation probably gets me a trimmed, chamfered & de-burred measured piece every 20-30 seconds.

Edited for clarity. Edited again: "3M", not "GM". Heh.

 

[jonas66]

I was striving for 1.175. My cases measured 1.1748-1.156. I wasn’t good with .008 variance. I posted on here, but a typo on length made my question weird.

Better at between 1.1748 and 1.151. But why can’t I cut 2 pieces of brass the exact same length??? And it’s taking me 45-60 seconds to trim from around 1.1762 to 1.175. Is this normal?

I'm assuming there are a few more typos here...

 

[kalielkslayer]

I'm assuming there are a few more typos here...

Yep. Fixed.

Maybe I should proof read before posting?

 

[jonas66]

Sorry- I wasn't trying to be a grammar nazi...I was referring to your listed case length measurements.

Are you really trying for 1.1750"? Or 1.750" ? etc., et al..."1.1748" Shouldn't that be "1.748" ?

I know everybody probably knows what you mean, but to avoid confusion...

 

[Bfh_auto]

I trim by hand with a Lee trimmer. Length is determined by preset pin. I have never been faced with such a large lot nor sich a predigious task.

I get small variations; before you measure, carefully chamfer ID/OD, because there may be small "whiskers" that can affect your reading.

Same thing I use. I chuck the cutter head in a drill though. I don't get noticable variations after I de burr.

 

[Cypress]

The fastest way I’ve found to trim that much brass is the Little Crow Gunworks WFT. 5 seconds per piece until your fingers wear out. Takes longer to deburr than to trim. They come out +-.001 with good technique.

 

[kalielkslayer]

So I tightened up the collet today so it was hard to get the case in and it made a difference, in consistency, not speed.

But I have a plan, kinda scary. Set the 2 trimmers up, side by side. Tie a flat bungee cord around it. Put a case in it and let the bungee do the work while I turn the other case 90 degrees, deburr, measure and put another case in, repeat.

I’ll see if that doubles my production.

And next time I size I’ll pay more attention to consistency. I truly believe I’m not setting the shoulder back enough on some of them. And I have both a full length die set and a small base die set. I don’t think I used the small base set on these first 250.

 

[AJC1]

I

So I tightened up the collet today so it was hard to get the case in and it made a difference, in consistency, not speed.

But I have a plan, kinda scary. Set the 2 trimmers up, side by side. Tie a flat bungee cord around it. Put a case in it and let the bungee do the work while I turn the other case 90 degrees, deburr, measure and put another case in, repeat.

I’ll see if that doubles my production.

And next time I size I’ll pay more attention to consistency. I truly believe I’m not setting the shoulder back enough on some of them. And I have both a full length die set and a small base die set. I don’t think I used the small base set on these first 250.

You will have to trim more or again if you use a SB die. Brass only goes one direction.