So who all full length size new brass? I have got different answers on this some people say they do others don't. A few Google searches came up with a guy saying the accuracy is way different. So thought I would see what you folks had to say on the subject.

I always do. Check the length too. Winchester brass especially. Case mouths get battered a bit often. I have a neck sizing die for my 22-250 but quit using it. The improvement in accuracy is not much and quick reloads are a problem. Takes a lot of forward pressure on the bolt sometimes. For hunting full length is better IMO. So they all get ran through FL die since thats what I have.

I still full length size the first time , it may hardly give the handle much resistance on the press at all but every once in a while you get one that does or has some issue.
New doesn't mean always perfect

I don't often get new production brass any more and the fired stuff I have bought in 500 or 1000 piece lots of cleaned but not sized Definitely needs to be sized.

with my 308 ammo for bolt action rifles after the initial loading , I use a Lee collet neck size die , but I keep those rounds in labeled 50 round boxes labeled with the gun they are for this makes them reload fast because they don't need trimming then FL and trim on the 4-5th reload.
those are mostly shot at bench or mat rounds if they go hunting they go in the bucket for FL and trim
my 308 really don't need the shoulder set back hardly at all I am not trying to hot rod anything.

I just went through this last week and did not size new Hornady brass. I had 5% fail to fully chamber. Pulled the decapper pin and resized all the primed brass.

Found a bad case in a bag of WW bulk brass. It was a WSM223 run on a WSM300 die. Had almost no neck because the smaller case was stretched so much.

Sent it to WW with a letter. No reply in 10years.

I check new brass for cracks after getting a bad batch of Winchester 257 Roberts. It had 6 with cracked necks Winchester refunded me a sent some coupons. That being said I just run new brass through a neck sizer.

About 6 to 8 years ago, asked a friend who is an experienced reloader, to load me some 6mm Rem rounds. He bought 3 bags of R-P brass, he did everything right, except he assumed that since it was new brass, it was good to go, so he loaded it as it came out of the bag. When I tried to shoot it, one entire 50 round box, none of the rounds would chamber. Some were as much as 0.004 over a no-go gauge. Others were simply to fat to chamber. Of 150 rounds, less than 50 of them would even chamber.

So a few years back, I geared up to reload on my own, so ended up pulling down the majority of it, then got to resize it with primer still in place. It all shoots fine now.

But lesson learned was to size it all and to check it all for length after it is sized.

A year or so back, bought some Lake City pull down brass in 308, and resized all that too. If nothing else, to get consistent neck tension.

Here, new brass gets the full spa treatment. Full length resize, trimmed to equal length, flash hole de burred chamfer and de burr the case mouth, then a round in the dry tumbler to get rid of sizing wax. That way I know I start with a batch of equal cases leaving less guess work as to why my groups are so bloody big

I think the other lesson is never make up more than a few rounds without trying them in the gun

I hear this frequently enough , loaded up 200 rounds 50 will load in the gun

why wouldn't you have checked any in the gun

I don't load for other people hardly ever but when I do you need to leave me the gun and I am going to shoot some to make sure they are right and all the dies are set and the load is good so far I have only done this for my brother.

you need a case gauge or the chamber of the gun your loading for to test

and how would you know if you have a good load without making some and shooting test groups.

At present I am using Lapua brass in my 308, Nosler in my 7mm RM, Remington in my 338 WM and 300 WM, and Winchester in my 223 bolt gun. When I take possession of a new rifle the first thing I do is buy a box factory ammo, usually Remington. I will fire half a dozen rounds through the gun, just dump them into the berm. This is the start of my barrel break-in, but that's another subject. Those cases are segregated and kept track of. Then I go to work on bedding the action and floating the barrel. While I wait for the epoxy bedding to fully cure, I give it 2 or 3 days. While I wait I use my case comparitor to give me a head space dimension using the fired cases. I use full length neck bushing sizing dies. Using the comparitor I set the die to bump the shoulder back .002 minus the neck bushing. I then turn the case necks using a K&M neck turning set up. The first operation is to use the neck expander that is sized to accept the turning mandrel. Then the necks are turned. I want to shave off JUST enough brass to get complete clean-up. You want to remove a minimal amount. Then I use a tubing micrometer to find out the wall thickness. I like to start with .002 neck tension. To get that state you take 2 times the wall thickness plus the bullet diameter and subtract .002 from that total. This gives you your starting neck bushing size. I order bushings .001 on either side of my target diameter. All this is done on the 6 cases from the factory ammo and a couple of your virgin brass. Once you have reached this point I put the neck bushing I feel is right in the sizing die and run these test cases through it, trim them to the proper length and seat a couple bullets just to double check. Make sure they chamber smoothly.

Now you are ready to start processing your virgin brass. Full length size with the bushing installed, expand the necks to take the turning tool, resize, trim to length, prime, powder, bullet, shoot. Put the neck turning tools away till the next time you want to process some virgin brass. There are other steps that I take like deburring the flash holes and squaring up the primer pockets on the Remington and Winchester brass. The Lapua and Nosler brass doesn't seem to need it so far as I have seen. I also anneal case necks every couple of firings.

I absolutely refuse to use digital calipers. They are simply not accurate. I have 3 right now that are relegated to the wood shop. None of them read close to size when checked with my gauge blocks and get worse over larger dimensions. They are almost correct on bullet diameters but go off in the weeds when checking case and overall lengths. Invest in a good quality analog micrometer and DIAL caliper, learn how to read them. I also have 1 and 3 inch gauge blocks to check them and keep them honest. My measuring tools are Brown & Sharp. My tubing mic is Mytitoyo. They are adjustable if they go off which is unlikely if kept clean and used carefully. I use the Hornady bullet and case comparitors which simply attach to the calipers.

This road to real accuracy and precision isn't cheap. It takes some cash and is time consuming. Money, there's more where that came from, and time, sure beats watching the idiot box. At present my 223, 7mm RM, and 300 WM give me 3/8 inch groups at 200 yards. My 308 goes 1/2 to 5/8 inch at 200 but needs more work with powders and bullets. The 338 WM is just under an inch at 200, good enough for whatever I want to destroy.

In my case, he did have the gun and claims to have shot some, which makes rest of it curious. In one batch of 50, many did chamber, so maybe he shot the good ones, then just went to work loading?

Now that I'm in charge, I found the fired brass to be about .001 less than no-go chamber length as determined by a no-go gauge. I set the full length dies so they will bump shoulder back about 0.001 to 0.002 less than fired length. Then check to make sure all of those will chamber, and check if they need to be trimmed. Once loaded, will check again to see that all will chamber.

Just discovered that Forster makes a depth stop ring for their full length sizing dies that has markings on them set in 0.001 increments. So if you want to adjust them up and down a known incremental amount, you can.

HayDay, Redding makes a set shell holders that does the same thing.

When my son finally got his custom built 300 WM I got my hands on 2 bags of virgin Winchester brass, both of the same lot number. Ran them thru the full length sizer and just on a whim we tried chambering some of them. We ended up doing them all. Forty-nine of the 100 absolutely would not chamber. Being the anal engineer that I am I gave them to a toolmaker friend who took them to work and put them on the optical comparitor. They were all okay for length, just a couple thousandths over trim length. The diameters were good. The killer was the belt, it was too long. They did however chamber in his old 300 that just shot almost okay even with tweeked loads. That gun and cases got sold to a guy that was ecstatic with a gun that shot minute of trash can in his hands with his loads. All the virgin brass I get is run through its corresponding gun before anything is done to it.

I also do as Scuba does. All brass gets a dry tumble to take care of the sizing wax. I use Imperial Sizing Wax, far less mess and waste. All fired brass gets deprimed and run through the wet tumbler with stainless pins before being loaded.

All this prep and loading may seem tedious and time consuming. But I personally find it very relaxing and satisfying.

I am a cheap skate in that respect and use feeler gauges to set the dies up and write down the values on my loading chart.

I size, check length, trim if needed and chamfer case mouths on new brass.

Depends on whether the brass was last fired from my gun or range picked up brass, my gun just the neck picked up brass full length

x2