Case length tolerance

If it matters, .223, varmint contour, 26" barrel.
Haven't found anything definitive in searching. For general plinking(no bench rest accuracy needed, just decent groups), wondering about case length variance around the 1.750 recommended length.
I can trim to ~1.750, but sort 1.746-1.751, and call it good. Without going through unnecessary testing, have you experienced much difference in this small tolerance, and could I even go down to 1.743, without sacrificing much?

Basically, have you found 1.743-1.751 to be good enough or should I stay closer to 1.750?

Aside from getting way too long and not chambering, I have not found any noticeable difference between freshly trimmed necks and those that are 1 firing from needing trimmed, which are about .005" longer than the fresh trimmed. Consistency is the goal, so a better tool would give you more consistent trim lengths but is it worth $100 to get an le wilson or forster trimmer?

The Wilson trimmer is awesome. Well worth the money, at least to me.

For general plinking 1743 to 1751 is good enough. The concern is getting them to long which will give you a pressure spike to the moon or worse.

I like to get them as close to the same length as possible.

For general plinking I use a AR or Rem 700 with cast in the 223.

1.760 Max
1.750 Min
You are OK but the brass is short under 1.750

Don't trim until you get to 1.760. One reason to keep it in the correct range is carbon buildup.

Quote:

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Originally Posted by Robinhood

1.760 Max
1.750 Min
You are OK but the brass is short under 1.750

Don't trim until you get to 1.760. One reason to keep it in the correct range is carbon buildup.

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From what I can find, SAAMI says 1.76-.030, which means 1.730-1.760.
I am just trying to learn from other's experience if 1.751-1.743 is going to change POI more than MOA.

You are correct on the saami drawing. However most manuals will tell you to trim to 1.750. I trim to the book. They are smarter than I am. Longer necks have been claimed to have better accuracy. shorter necks have been rumored to cause carbon rings. The sky is not falling. It is your brass and your rifle. I think you wont notice a lot of difference for short range stuff.

Thanks Rh for the longer necks info. I was not aware of that.
My original post mentions the 1.750 target length, so I am aware of that. I have been trimming everything >1.752 back to 1.75. Sometimes they come out 1.748. I have a few pieces that are in the 1.745 range, would like to use them, and thus my question. I'll leave the longer ones alone for now as long as they are not over 1.760. Since I neck size only, I don't get much growth after my first firing, and little trimming is needed.
Obviously, group size will tell me if if I need to change.
Sounds like I can use the shorter ones with little concern.

Typically SAAMI spec chambers are always .020" longer than stated max length. If you measure your chamber length with a plug, it's probably closer to 1.780". SAAMI states 1.772-1.787".

Quote:

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Originally Posted by Robinhood

1.760 Max
1.750 Min
You are OK but the brass is short under 1.750

Don't trim until you get to 1.760. One reason to keep it in the correct range is carbon buildup.

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I find that the regular use of a pistol bore brush that closely matches the neck area ID keeps carbon buildup to a minimum. I set my trimmer (Wilson/Sinclair) and just leave it alone (I do periodically check however). Some new cases are a little short but a few firings later they have grown to the point they need a little trim.

In my shooting I don't find case length to be a big accuracy factor. Neck tension, yes, but a few thousandths of difference in case length doesn't seem to contribute all that much effect. Maybe on paper it might but apparently so small that I can still get sub .25 MOA performance even with cases varying in length .005" - .010". I just want the cases short enough so they fit in the chamber and don't expand under firing to the point they create high pressure as the bullet is leaving the case.

Quote:

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Originally Posted by Deadshot2

In my shooting I don't find case length to be a big accuracy factor. Maybe on paper it might but apparently so small that I can still get sub .25 MOA performance even with cases varying in length .005" - .010". I just want the cases short enough so they fit in the chamber and don't expand under firing to the point they create high pressure as the bullet is leaving the case.

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Thanks, Ds
This was the kinda info I was looking for. I realize every chamber is different, but I will feel more comfortable not being so picky.

Ok, my take is as long as your length is consistant you are good. I don't know if it makes that much difference, but as long as its not too long (or gets too short) no issue.

You can process at very fast speeds and its darned accurate. Maybe .004 variation. I would guess I can do 500 in 30 minutes.

I will also make some recommendations.

My brother had a Gerara self diven and it works wonders, he has 4 or 5 heads for it for the different calbiers and easy to swtihc. Also first jump in is costly.

I went with a drill driven, but came up with a variation that rivals (comes close) but does not exceeed the Gerard self diven unit.

I clamp a 1/2 inch drill in a vice, no hand holding. Set the speed and lock the trigger. You can buzz through them really fast.

1. Off the shoulder trimmers are the best.

2. I have tried two of the three and have the third on the way.

a. WTF: Good enough, the II has inserts so you can change to different calibers. You still have to chamber and de-burr.
Not a bad choice, mine worked good enough, I like the Gerard with the deburr and chamfer though. About $100 for the II that allows caliber changes.

3. Gerard: Two choices, Tri Trimmer which works in a drill, my favorite but you have to buy a separate one for each caliber.
No 7.5 Swiss so that one was off the table. Around $100 for each caliber.

4. Trim it II: I went with this one as it does the 3 way cut, but you can get different inserts. That allows a lower future change and still uses the drill for the driver.
Mixed reviews, early ones not so good, latter ones much better. Have to see.

You do have to set the cutters for each new insert, so how annoying that would be will see if I go another caliber. $150 or so with a caliber insert.

I do keep 500+ cases on hand so I trim a bunch at a time. The 7.5 PPU came in at the long end.

The two I have had are quick, accurate and no fussing.

delete

I use a WFT trimmer for my Lake City brass that trims off the shoulder location so the OAL of the case varies approximately the same as your trimmer.

I use this trimmed brass in my AR15 rifles and my Savage .223 without any problem.

https://littlecrowgunworks.com/wp-co...09/WFT01-2.jpg

I use foam bore cleaner in the chamber and bore and never have a carbon problem in the neck of the chamber or bore.

The foam bore cleaner lets you use the minimum cleaning rod time in the bore. Spare the rod and spoil the bore.

Below one shot of foam bore cleaner in a pitted and frosted No.4 Enfield rifle removes all the copper and carbon when left to soak overnight. (without any brushing)

https://www.milsurps.com/images/impo...IMGP5065-1.jpg

Below a bore scope photo of a Savage button rifled bore that will "eat" copper bore brushes just like a pitted and frosted milsurp bore and give false copper readings.

http://i.imgur.com/GpTCke2.jpg