Well, I just started reloading a month ago and have been reading about the subject as much as I can.  I've also spent time watching reloading videos from Rex and 8541 Tactical.  I'm specifically reloading with precision in mind and picked up a basic Lee single loader and a set of Lee .223 dies.  I have the four die set that comes with everything you need essentially to get started, Lee Die .  When I first jumped down this rabbit hole it seemed like a very complicated process, and then after watching the two above You Tubers, I felt far more confident about the process.  However, the more I read on forums such as this one and sniper's hide, the more my head began to spin.  Well I went with the techniques demonstrated in the videos and reloaded a enough rounds to conduct a ladder test as well as about twenty rounds based on the "accuracy load" in the Sierra manual.  Long story short, they did not blow up me or my rifle and they all fed without issue, so I count that as a step in the right direction.  

Now on to the point of this thread, I have a few questions I would like to ask you all here with the hope to provide some clarity.  Before I get to the questions though, I wanted to explain the rifle I will be loading for.  It's a custom precision AR built by myself and uses a 20" Larue barrel 1/8 and a Larue MBT trigger.  Here's a picture of the rifle.



Questions:

Case Length:  From what I've read I want consistent case length for all of my rounds, however after sorting through all of my .223 brass by brand, all of it 1x fired by me, it's all different lengths.  For example, I started reloading only my PMC brass, and after using the full length sizing die, the individual brass cases range from 1.73 to 1.76.  The specification say they should be 1.76, but the majority of them are well under that 1.73 to 1.74.  Does the case length play that huge of a role in precision as COAL does?  Should I be taking the shortest case and trimming all the other cases down to that length so that they are all equal?  Do I run the risk of having too short of a neck?

I keep hearing about seating depth and distance from the lands being important.  I've been trying to find the Hornady tool for this specific measurement, but it seems to be out of stock in many places.  I know this is very important with bolt rifles, and soon I will be reloading for my 6.5 creedmoor Tikka T3x.  When it comes to my semi-auto SPR, is the seating depth and COAL really that important since I'm so limited by the magazine?  Should I be doing anything in this particular facet of reloading with my semi auto?

Crimping with the Lee set, is it important for semi only?  To Crimp or Not to Crimp?  The Lee manual that came with my dies recommends crimping as a way to increase accuracy.  I've read on the other hand that most precision reloaders are not crimping unless the bullet was designed to be crimped.  I'm currently using Sierra 69gr Match King BT's so they are not technically designed to be crimped.  I've read in places that crimping is not necessary on bolt guns, but should be recommended for a semi-auto due to the violent manipulation of the bolt.  What says the hive?  I know that my bullet seating die does not crimp at all, while other dies may offer a small amount of crimp as the default.  Again, this is an area where I am confused.


Thank you for taking the time to help a new reloader.  Lastly, because moar pictures are moar better, here's a pic of my 6.5 creedmoor.  She's shooting .5 MOA with Prime 130gr, which has me wondering if I should even bother reloading for it lol.

To your 3 areas of question:

1) Consistent neck tension is important to BR shooters, and they will go to great lengths to maximize the likelihood of consistency. Some will trim all brass to the same length, some will depend on neck turning and/or actually measuring the force required to seat the bullet. It is possible that different length necks will exert different tension on their bullets, but IMO the differences if any are not likely to be measurable on paper.

1.76" is not the "spec" for case length, it is the max you should allow the case to grow unless you have used relatively sophisticated techniques to ensure your chamber can handle longer necked cases. Normal procedure is to trim brass as required to 0.010" below max . . . or 1.75" in this caliber. This allows for multiple firings before case growth requires re-trimming.

You will find many factory cases (particularly Federal) start at lengths significantly shorter than 1.75". For me and my rifles, they have always shot the same as longer cases and required less re-trimming. Since YMMV, I'd recommend you start by trimming any (if not all) brass to 1.75", shoot it, note the growth, learn, and decide for yourself whether/when you will take more detailed steps. It will take a lot of work to only shoot brass of exactly the same length, and it probably won't yield a noticeable difference.

2) Unless you are going to single-load, you are restricted to magazine length. Chasing the lands is not possible, and varying the length within mag length is unlikely to provide any measurable advantage. Once again, YMMV . . . it's theoretically possible your rifle, chamber, bullet, case, powder, charge, and primer may for some reason like some shorter length. But it is unlikely to be measurable.

It's a different story in your bolt actions if you are willing to single-load. Both powder capacity and accuracy are likely to improve at  some small distance before (jump) or into (jam) the lands.

3) I personally would only crimp bullets with a cannelure. It is unnecessary and may in some cases damage the bullet impeding accuracy. FWIW I no longer crimp the only cannelured bullet I use, the Hornady 55gr bullets I use for "plinking". Once you have found a good load, it's worth testing the difference on your own. Testing is fun, educational, and gives you a reason to shoot other than making noise at the range :)

Twoboxer, thank you for taking the time to reply and answer my questions in detail.  I feel much better about not crimping now and thank you for clearing up the misunderstanding around maximum case length.  I can't wait to try out some new loads I just made up this Sunday, thank you again!

To the OP

#1 Get some good loading manuals.  I suggest Lyman 50th and Hornady.  You need sit down and quit watch videos, and you need start reading information.  Read the front of the Lyman serveral times and make notes.  Then seek clarity.
#2 Do not get ahead of yourself.  Your #1 goal threefold - Safe Reliable and Accurate reloads!
#3 Learn and experience success keeping things simple!  KISS METHOD!
#4 You mention hodge podge of things, and it is evident you  have not clue as to why those actions may benefit you!  Trust me you need to have success with the simple steps before moving up your skill set.  So down the road you can invest in the two reloading books Glen Zediker had written.  Then help expand your horizons of the why when doing certain chores.
#5 So many people will throw opinions your way, but it is hard for you to discern the valid stuff from the idiotic!

You just have to invest yourself and establish your capable of generating accurate reloads!

Work on one caliber and then branch out!

Thank you, to be honest I've done 90% of my reading via forums, 10% gathered from my Lee die instructions and then added in You Tube videos as well.  I have the Hornady manual and the Sierra manual, I will take some time this weekend and read through the instructional chapters.  Thank you for the words of caution and I am definitely sticking with .223 until I really get a better understanding of the process.