I FL sized amd reloaded about 20 rounds of 270. Some will chamber fine and fit in my checker and others are a little tight on the bolt and the bottom of the shell hangs out a tad of the checker. It’s about 50-50 in the batch and random throughout. When I sized I bumped the shoulder back a tad. COAL and CBTO measurements are all consistent from round to round. What would cause this and is it safe to shoot or pull the bullets and start over?

Did you trim the brass after you resized it?

Few things.like said above did you trim brass or check length?

Also ignore the gage .I'm assuming you a have a case gauge is what your talking about? Really only helpful if your sizing for several different rifles or pistols for a one size fits all without oversizing or sizing least you can making ammo to fit multiple rifles or pistols.otvhrwise they are useless.also burs on case rims can cause brass to not slide into a gauge.anyways just use your chamber fo fit.you really want to make bolt action rifle ammo only fit or customized to each rifle

Otherwise you needed to turn down die some more to avoid tight fit.its ok to shoot with slightly tight bolt drop just barely though.you will wear down back of locking lugs if forcing bolt down all the time.hard camiing

Probably didn't size enough and safe to shoot.people who neck size run into this eventually you have to bump shoulder back slightly
You just don't want to force down bolt.a slight bit if resistance is ok

Also one other thing if using once fired brass from another rifle.it could have had chamber on extreme side of headspace and once you fire in your chamber they will be fine.ive had to use small base die before on brass once fired from unknown rifle but normally this isn't necessary but it does happen.dies are designed to bring brass back into middle of headspace without over sizing but sometimes they can't overcome excessive headspace from another rifle without small base die.

Most likely you didn't size enough and needed to keep bumping till brass chambers
It's best to start with new brass and fired in that specific rifles chamber.

but anyway I have zero idea of what you know or have done just giving information

I appreciate the help. Still pretty new to reloading. I checked length and trimmed after resizing and yes I was referring to a case gauge. Now that you mention it, some of the brass I used has been fired in my rifle once. When components were more scarce I did purchase some once fired Winchester brass ( also had Winchester brass from my rifle). I just FL resized everything in one batch and guess some of that could’ve gotten mixed in. That may be the cause of the issue. I probably didn’t tighten down the die far enough in retrospect. I just thought that FL sizing would get everything back to spec. I think I checked the first few in my gauge and thought the rest would be fine. Luckily it’s only about 20 rounds and not more. Is there anything I can do different next time?

3% offered good advice.

Get yourself a Hornady Headspace gauge. Very easy to use and helpful tool.

Don't mix your brass.

Get a bump gauge too

What lube are you using inside the case necks? I n the past, with a rough expander ball in the sizing die or not enough lube in the neck, I have pulled the shoulder angle forward when withdrawing the case from the die. A good idea is to use a brass brush (dedicated just for this purpose) to clean residue from the neck.

One other possibility you could have bullets touching lands/rifling.if your shooting a heavy bullet for cartridge .best to take time to find lands before Seating bullets.ive run into situation years ago where I didn't take time to find lands and seated bullets by the book and rifle barrel had a very short throat compared the every else I had fooled with in that cartridge.any way I was jamming bullets into lands this can happen also and cause heavy bolt.

But to answer your last question.you can mix and match brass brands and number of firings but you'll need to completely full length size to shell holder just like your dies instructions say.but only load those 3-4 times max so you don't have split necks or possibly case head separation.your losing out on top accuracy mixing up brands and number of firings but they can and will work for ok groups just for deer hunting and or learning .

Top accuracy keep all your brass on same number of firings and same lot.dont mix em as said above

Just blasting stuff out of a AR go ahead mix it up for shtf or whatever but yeah if your wanting precision don't mix brass .brands or numbers of firings

To answer above I’m using Hornady unique lube I think. I’m not at my bench so I can’t check. I found the lands and seated the bullets back 30 thousandths. I also have a headspace gauge and bumped the shoulder back slightly. I used a q tip to clean the lube from the neck because it’s what I had on hand at the time.

I appreciate all of the help. Like I said I’m relatively new to all this. I followed the manual and watched a ton of YouTube videos. Panhandle Precision has been very informative. Just scratching my head on this one. Straight wall cartridges are a breeze.

Hmm only 30 thousandths back from lands? I'd bet a little more jump will fix the issue.

30 thousands is plenty of jump.

Brass from different lots/manufacturers can cause variations in headspace when resizing.

A “tad” isn’t a measurement. How much did you bump the shoulders back on each piece of brass?

Also if your lube was inconsistent from piece to piece, your shoulder bump may be also.

I’m back at home from camp and and looked at my notes this morning. It seems that my measurement before and after sizing to the shoulder were the same. So I didn’t bump the shoulder back based on what I can tell. Here are some pictures of what I’m seeing. 1st photo has no issues, 2nd and 3rd pics are a different shell. Case trim length is the same and seating depth is the same and is 30 thou off the lands.

Sounds like some shoulders were bumped a “tad” while others were not.

Definitely need a comparator to measure shoulder bump.

In consistent lubing equals inconsistent shoulder bump. Shoulder bump will also vary between different brass manufacturers or lots, with no adjustments made to the sizing die.

Check case size where it hangs out of the gauge then measure one that fits

Good point and you could be correct. I do have a comparator that I used to measure the length to the shoulder before and after resizing. I didn’t find that the measurement increased so I did not set the die to bump the shoulder, at least according to my notes. I did take measurements of a few and average them so there could certainly be outliers.

The good news is that I have a ton of brass that I have FL sized and the rest fits in my case gauge after resizing now. Just want to figure out what happened with these particular loads.

Good idea. I’ll check

That gauge you are using is only useful for semiautomatic pistols and semiautomatic rifles when you are wanting ammo to fit several different firearms .and if ammo isn't sliding into gauge you didn't size enough.its that simple
When you mix brass it takes different amounts of sizing to fit it back to your chamber.

So basically with what you are doing with the mixed up brass just completely size down to shell holder to use up that brass or you at least need to size a good 4-5 and check in your chamber for tight bolt.just for blasting ammo or just good enough hunting ammo they will work fine

But in future get the hornady headspace comparator to bump shoulders and keep up with your number of firings and start with new brass if precision is what your looking for.if your just looking to use up once fired mix match brass fired from a different rifle just size to shell holder and be done .no since in fighting it .you can't size mix match brass the same without oversizing all of em

Honestly bud read several reloading manuals and load ammo by the book.then start watching panhandle precision or other vids
You got to know basic fundamentals and safety to start.if you had read reloading manuals and set up your dies per instructions you would not be here asking questions.
You mentioned panhandle precision.great vids but that's advanced you need to know basic knowledge of hand loading.the same understanding we all know and will give you confidence and basic knowledge
But read 2-3 reloading manuals.read front to back for safety and basic knowledge we all know
Your question you just asked would not be have been a problem if a you had done so.now this is where you start learning advanced hand rolling .interwebs .lol

Not saying this is the problem or to be mean spirited but did you lube a little bit heavy? Yes I've done it myself more than I should but lube can dent a case in a heartbeat.