Neck Size...Or... Shoulder size, back .001? Help!

[hilblly]

Recently I read a thread on shoulder sizing so it is .001 or .002 back.
I can't find the thread. I am shooting a .270 Win. I am neck sizing now about 3/4 of the way back to the shoulder with really impressive results, but I am always striving for more precision and more information. I am relatively new to brass reloading, I have reloaded shotshells for years.
I am confused on this sizing the shoulder back. I have the Lyman and Speer manuals and spend countless hours reading both (My wife says by now I should have them both memorized). They both suggest neck sizing for best accuracy. What die is used for the shoulder sizing and how is it set.
Can some of you "long timers" out there help me out.
I am looking in to the Stoney Point gauges for measuring OAL and headspace.
Any and all help will be appreciated. What else should I get?
Thanks, Mike

[j0hnlewis]

I've never heard of shoulder sizing, I've been reloading for about 10 years now. I use a stoney point OAL guage and love it, it works great! If you'd like to go even deeper into case uniformity I'd try a case neck uniformer tool, this tool effectively centers your bullet in relationship to your barrel by chamfering the outside of your case neck. You never listed any tools you already have so I'd recommend Midwayusa.com and also look at flashhole uniformers, and primer pocket uniformers, you can even weigh cases and group them in lots of 3 (or 5 if you shoot five shot groups) of similar weight in an effort to recieve the same case capacity for each round in that group of shots.

[Jaywalker]

I'm also not sure of the meaning "shoulder sizing," but sometimes we do refer to "pushing the shoulder back." Is that what you mean?

If so, there are definite benefits towards moving the shoulder back a small amount, as opposed to following the default setup instructions written by the the full length die maker. The die maker wants to ensure that you make a cartridge that fits in even the shortest chamber, and the chamber-maker (gunmaker) wants to make sure that you can load the longest cartridge that an ammo maker boxes for delivery. So, under some extreme circumstances, you get a cartridge that rattles around in the chamber (figuratively speaking). This is "excess headspace," and while it may be (almost certainly will be) within limits for safety, it's not particularly conducive to accuracy or long case life, what with the case being stretched, resized, and so forth.

Again, if this is the issue you're describing, then the Stoney Point OAL Gauge isn't the right answer. The Stoney Point OAL Gauge, particularly along with their "Comparator" will allow you to set up the proper bullet jump to lands, but doesn't address headspace.

For headspace, try the "RCBS Precision Mic" in the chamberings you load. I have one each for 6.5X55 and 7mm-08, the two cartridges I'm currently loading. The Mic allows me to set the headspace precisely for my individual chamber, rather than to SAAMI minimums. I set the FL die to move the shoulder back about 0.002", and I like the results.

I also have a Lee Collet Neck Sizer for the 6.5 Swede, but I use it less than I have previously. Yes, it provides accurate, loaded cartridges, but, no, it's not the end-all answer. Cases eventually get hard to chamber, and "hard to chamber" is another way of saying "wear on the bolt lugs and lug recesses," and wear on these areas will defintely affect your headspace. I found myself having to FL size pretty often anyway, so I bought a Forsters FL Die (and the RCBS Precision Mic) and just always use that approach now. My RCBS Casemaster indicates the runout values are within my requirements when used with a quality seating die.

Jaywalker

[hilblly]

Thanks guys, for the info
I believe that "setting the shoulder back" is what I had read. So if I am hearing correctly this is done with FL sizing die, but not set all the way down to the shell holder, set down only far enough to set the shoulder back .001" or .002". I will try that also, instead of just neck sizing, as it seems logical that only neck sizing every time will make the cartridge hard to chamber. Do you find that the accuracy is the same as neck sizing or better, worse? I will definitely look into the tools you both described and test the results at the range. I love this forum, I would have much longer and harder to get info on this.

Thanks again
Mike
Any more info out there?

[Tom Matiska]

"Neck sizing" by backing off your full size dies(partial resizing) as opposed to buying neck sizing dies has its limits. For cases with a lot of shoulder like my 243(or your 270) you may find that the unsupported shoulder can distort. Or you may find you can do it once or twice, but maybe not three or four times before the case stretches enough to need full sizing.

I shoot the 243 little enough that full sizing for deer season and partial sizing for groundhogs suits me, but if you need that last little bit of accuracy all the time you may want to get some necksizing dies.

[hilblly]

Thanks Tom for the info.
I use a neck sizing die now with some really good results, but I am not sure how many times I can just neck size before my cartridge chambers with difficulty. Maybe I will do a combination of both, neck sizing for a couple of firings and then using the FL die setting the shoulder back for easy chambering. Thanks again for your info.
Mike

[LSUBOY]

Go out and purchase a RCBS Percision Mic. for your caliber.

Hart and Sons say that the best accuracy will be when you have about 15 thousants of headspace. That's the distance from the shoulder of your case to the chamber. Exceed this amount and accuracy suffers. That's why lots of folks like to size the neck of fired cases. However, if you intend to full length size your cases, {which means sizing the shoulder down a small amouht} then you need to know how much is just enough. For this you will need the RCBS Percision Mic.

When you fire a round in your rifle, the shoulder of the case contacts the shoulder of your chamber, then springs back a little so that you can open the bolt. Therefore, when you check the fired case with the Percisison Mic., you don't want to size your cases down any further that that amount. To do so would mean that you are adding excessive headspace to you reloads thus accuracy will suffer. Go too far past this amount and all sorts of problems can crop up.

If you don't want to purchase an RCBS guage then just start adjusting your full length die down on a fired case until you can feel a slight rub of the case in the chamber. You want to feel the case rub in the chamber / what you want to avoid is the chamber closing as if there is nothing in it.

The answer to your question is you can size the neck or neck & shoulder of a case, however, if you size the shoulder of your case, you will be sizing the shoulder and neck.

[Nnobby45]

You're referring to Full Length resizing so the die resizes the body to a small degree and also sets the shoulder back slightly so the round will chamber easily. If you keep neck sizing, the brass will get to the point where it loses it's elasticity and won't retract fully after expansion from firing. You'll have to full length resize eventually, but by that time your brass will be on the brittle side and won't respond as well. There are dies made for Neck sizing and those for FL sizing. I like RCBS dies. Accuracy? Benchrest shooters FL size (to a small degree) their cases during competition.

I prefer to FL size each time just enough so that the brass will easily chamber. You may have to size in steps. Blacken the case (or use a magic mkr) and adjust the die so that light contact is made with the shoulder (barely) Chamber the round to see how you're doing. Like, go down 1/16th of a turn at a time until it chambers properly. NOTE: Your case will get bigger during sizing, (and might not chamber), until you reach that point where the die sets the shoulder back the required amount. Do not force the bolt down on a case that feels tight. You should remove the firing pin and spring for better feel. Do not size more than you need to, or you will create more case stretch and risk an incipient head seperation, eventually. There's a world of information to be had at Sinclair International. Good techs than can help you out. You will get a catalog, and can get the small Sinclair manual on precision reloading. This subject could take up the whole web page, so I'll let it go for now.

[Nnobby45]

I'm sure you didn't mean to, but your reference to 15 thousandths being the proper head space for best accuracy was a mistake. 15 thous (.015) would be such excessive headspace that a ruined rifle, if not a ruined face would be the probable result. Neck sizing may produce 1.5 thousandths (.0015), and that would be a tight fit. I suspect that's what you meant.

When a cartridge is fired, the firing pin forces the case fully forward and the pressure forces the expanded brass tightly against the chamber walls to create a tight seal. The thicker part of the case near the head can't expand that much, but the pressure (50,000 PSI, for example) causes it to stretch backward and slam against the bolt face. The distance from the case head to the bolt face, is the simple definition of head space. Think of headspace as how much your case will stretch upon firing. 8 thous. would be excessive. Better to have from 3 to 5 thous. for quality, and easy to chamber hunting ammo. Target ammo can be tighter. Two to three thous., or so.

All may not agree, and headspace can be somewhat controversial, but it's mandatory that the handloader understand it. Do it wrong and your round may not chamber, or you may create enough excessive headspace to blow up your gun, and maybe you.

[CaseyC]

Hilblly,

The posts here are good ones, especially Nnobby 45's, but let me (attempt to) add some things. I often see some confusion about different types of resizing operations when folks start out reloading. So we know what I am talking about:

1. Small Base resizing (S.B. dies). Resizing with Small Base dies sizes the case back down to original (read, SAAMI) specs. Common wisdom says this should be done for autoloaders and lever guns (but actually not always needed). Small Base resizing works the brass the most.

2. Full Length resizing (F.L. dies). These, when used in a "conventional" manner, sizes the entire case (neck, shoulder, and body). But, doesn't size the case "down" to orignal specs.

3. Partial Resizing (This is what you're referring to--I think). A F.L. die is used to size the neck and "bump" the shoulder back just a tad (the .001-.002 that you've read already). Generally speaking, the body of the case isn't touched by the die. Most manuals ( Nosler #1 and #2, the later Sierra's are helpful) have some info on partial resizing.

4. Neck sizing (Neck die). It only sizes the neck. Although I don't neck size my big game loads anymore (or at least rarely) I find a neck die can come in handy at times. But I do neck size for my varmint rifles.

I have loaded for the 270Win as much as all of the other cartridges I have owned combined. I have never seen any significant improvement by just neck sizing--but I have experienced a decrease in accuracy at times. So, it seems my best loads are partial resized.

The RCBS Precision Mic and Wilson case gauges work very well, I own two Precision Mic's and one Wilson gauge. But these days I exclusively use my Stoney Point Head and Shoulder gauge. Stoney Point also makes a Bullet Comparator for measuring the overall cartridge length (C.O.L.). The same body works for both tools and all you need are different bushings. For the price of two Precision Mic's a guy can buy the Bullet Comparator set (with bushings to cover most bullet diameters) and the Head and Shoulders set of bushings (which covers most cartridges). I have a caliper that is dedicated to the Stoney Point body, then it is just a matter of changing bushings.

Now for the "method" of partial resizing: Screw the die down until it contacts the shellholder with the ram in the full up position. Unscrew the die until there is, oh, the thickness of a nickel (or more) between the shellholder and die. Run the case into the die (don't forget to lube ). Comparing the sized case to a fired, unsized case, measure (with your choice of tools) to determine how much the shoulder has been set back. Keep screwing the die down (a little bit at a time) until the shoulder measurement is .001-.002 less than the measurement on the fired, unsized case.

Hopefully, I haven't confused the issue.

Casey

[30Cal]

I'm pretty convinced that the die mfgr's instructions for setting a FL sizing die is just barely better than simply guessing. I highly recommend buying or borrowing what gages you need to be able to be able to measure headspace of fired and sized cases.

Ty

[Tim R]

If loading for a auto loader, setting the shoulders back is a must. This ensures the resized case will chamber without hangups while not over working the brass at the same time.

Brass used in bolt guns only need to be neck sized as the bolt has much more leverage to close on the brass. Neck sizing works until the bolt is hard to close, then F/L size.

[hilblly]

TFL does it again!!
Thanks for all the info folks.
I am ordering the appropriate gauges from Stoney Point.
Also ordered a catalog from Sinclair. Wasn't sure which reloading manual is the precision manual but I'll figure it out.
Thanks alot
Mike