I've never spent enough time worrying about cases. Today I started thinking about cases and how they contribute to pressure. I just finished reading about pressure in Richard Lees manual "Modern Reloading". It was the only manual that went into any depth. I understand that packed powder loads contribute to higher pressure.

But how about cartridge length as regards case length? I understand that a case after several uses will usually grow in length and should always be trimmed. But what happens with a short case? I recently bought some new 243 cases. I think they were Remington. They varied a lot. Some were the correct size of 2.045, but not many. The shortest I found was 2.024. If I load that case with an 85 gr Sierra and an OAL of 2.650 as recommended in the Sierra manual, I am seating the bullet 21/1000 deeper that I would on a case of 2.045 inches.

How does the variance in case length affect accuracy if I mix them? What would be the difference in pressure?

Just how much does this stuff matter to the average guy like me? I'm no longer a great shot.

SAAMI specs are a guideline. Get a headspace gauge, measure to the shoulders of 5 cases that have been fired in the rifle. Set the Full Length die to bump the shoulders .003". O.A.L. can be thrown out the window. Find where your bullet engages rifling, and set your bullets even with the lands. Then play with powder charges to find "the" load.

Fit your case to your chamber.

Seat the bullet to touch lands.

Pressure will be affected by the amount of powder charge, and how far the bullet is jammed in the rifling.

OK, first step is a headspace gauge.

Thanks

The differences in case length won't cause variances in OAL or pressure---or much else to an appreciable extent. They probably will affect bullet pull to some extent but probably not enough to worry about. If you want perfect consistency then trim them all to the shortest length, it won't hurt a thing. The bottom line is that the finished cartridge's OAL is governed by the seating die and how you set it up.

Seating to touch the lands may or may not work for accuracy. It is NOT a universally applicable accuracy technique.

Definitely measure to find the lands. I load for a 25-06 that when loaded with most 100-110 grain bullets to book/SAAMI specs the bullets are jammed and that is something I don't prefer on a hunting rifle.

I've always thought of headspace gauges, go-no bullets, as gunsmith or gun builder tools. Once again, I've been wrong.

I have some things to learn.

What headspace gauge tools would you guys recommend?

The comparator sold by Hornady that was once marketed by Stoney Point. The "specially modified" cases are unnecessary, but the comparator with a set of inserts is pretty much a must-have if you want to KNOW what you're doing.

PT&G

Somewhere in this forum is a thread where I explained the technique. If you can't find it, I'll dig it up when I get home and have access to my PC.

Oops. My suggestion is a tool for seating depth measurement. Sorry, I misread your post Dave.

About headspace, though...I personally don't subscribe to gauges for headspace measurement unless we're talking go-nogo stuff. The sizing die can be effectively set up without measuring anything.

Dangit, Riverrider I don't want to get into an argument with you, we've been getting along so well.

One can set headspace without the guages, but life is easier with the gauges. And the gauges aren't expensive. Can you go with me on that? I set every rifle/ case to full length size .003" shorter than what the fire formed case measurement was. I get all I can in velocity, cases feed, and eject, and they don't get over-worked.

I use the same method as FiremanJG does. The tool is available at cabelas or online. The one I use is made by hornady. If you purchase the same one let me know as I have extra headspace inserts I don't use and wouldn't mind sparing one.

LOL Fireman.

If you like your method and the gadgets, don't let me spoil your party! If you're happy with the way it's working out, then who am I to dispute that? I will not. On the other hand, the method I use requires no tools other than patience and the results are just as effective. I would urge anyone who likes to max out on gadgets to do so, but there's more than one way to skin a cat.

Now, it could be that my habits and your habits differ enough that my method wouldn't work for you...I do not have multiple rifles in a caliber other than my AR and my bolt-action in .223 Rem. I also load one bullet and one bullet only in a given caliber, but again with the exception of my AR. Because of the way I've approached this game I can set my dies up once and lock em down so I don't mind going through the setup because I only do it once. If you're loading for multiple rifles in, say .260, then measurement tools for setting up headspace could be a real time saver and especially if you write stuff down for future reference.

You should write everything down anyway. Im in agreement with FiremanJG I'm not fond of over working the brass if it isn't necessary plus your deviations will be less.

I bet your method works. I'm not a gadget guy, but I've got more tools than any two men I know combined. It's a sickness, and I accept it. I shoot three, nope, now four different chamberings, and all my friends bring me their rifles and brass to work up loads for them, so the tools have become an absolute necessity.

I'm also one of the biggest nerds you'll find. I can go back to the beginning of any barrel and see what I did, including head-space measurement. I can also read what the measurement was from case head to the ogive for that rifle/ bullet combo and see how bad the throat is eroding. Obviously this is a bigger problem with the 22-250 than the 260, but as much as I shoot, and as anal as I am wanting them to be sub 1/2 MOA or less I keep an eye on all of it.

I understand your passion and the depth of your absorption with the whole thing. When I began to really get into this rifle stuff 25 years ago I wanted to measure everything and have every relevant tool known to man and then some. I guess as I've aged I'd rather spend a little less time at the loading bench and a little more actually shooting and hunting.

Something I once figured out, and now is as good a time as any to mention it for the benefit of the OP: turning the lock ring on your sizing die ONE degree will change the shoulder-to-head dimension about 0.0002 inch. One tick of the clock's second hand means a movement of 6 degrees, and this much movement of the lock ring will move the shoulder by 0.0012 inch. So if you're trying to change how far you bump the shoulder by just one thousandth of an inch, very little movement of the lock ring is needed. It's a painstaking process.

To the OP, here's the tool you want and a great article on how to use it.

http://www.realguns.com/archives/093.htm

I've been learning here as well, and adhere to Fireman's methodology - especially for a novice such as myself, but appreciate the "measuring with a micrometer and chopping with an axe" aspect that all of this can take on too...

Todd

I must be reading the thread wrong because I generally go with this comment. If I reading this correctly the only way that the pressure would vary to your concerns is if the actual body & shoulder had the different variants in length instead of just the neck. After the first firing the cases should be close and fire formed. The short case will just grow, how long it takes to grow depends on the load. You could also smoke a bullet and see with a fire formed case just where the lands are. From first touching (lock bullet in place) measure and then turn seater die down X amount of quarter turns depending on its threads to look for best accuracy or you going to start needing a lot of expensive equipment to get less than 1/2 MOA. Make a dummy round after you find your best seating depth. Your'e starting to measure .0002, heck I got to much hyper tension to shoot that good. Like I said if I'm reading the OP correctly.

As far as I can tell, Dave wants to know about case length and trimming in the OP.

Dave, if I understand your post the way it's intended you seem to be laboring under the misconception that the case length is affecting seating depth. I think you may be looking at "seating depth" from the wrong angle. We rarely care how much bullet is in the case neck as long as it is sufficient to hold the bullet and that's not what seating depth is all about. Seating depth is about how far the bullet extends toward the rifling when the cartridge is chambered, and case trim length has absolutely nothing to do with it. It is determined by how you set up your seating die.

The only way case length affects pressure is if the case is too long and the mouth of the case is pinched by the chamber, causing the case neck to not be able to turn loose of the bullet. As long as none of your cases is long enough to cause that to happen, you will experience no problem...but it IS desirable to trim cases to a uniform length for consistency's sake.

The headspace issue is completely separate and unrelated. If I was you I would refrain from buying a bunch of stuff until you gain a little more experience.

Thanks all; I'm not new to reloading. I bought my first press about 35 to 40 years ago and turned out some good loads. I quit shooting for quite a few years due to raising a family, running a business, etc. Now, those same good loads are starting to hammer me pretty hard and I need to develop some lighter loads.

Now, I've hit the stage of not just how, but why. Regarding things like headspace, pressure, etc I realize that I'm pretty ignorant. In those area, I have one year of experience 35 to 40 times. One year might be generous. While pressure evidently isn't a problem, it's something that I want to understand.

I'm retired now, 70 yoa and in good health, and can buy just about what I want as long as my Wife doesn't find out about it. And, that can certainly be an issue. Actually, I not only don't want to spend $ on things that I don't need but have run out of space for new toys that I might not need.

I have trimmed my 30-06 cases but have always just seated to OAL.

Bumping a shoulder back tells me that I don't understand the die as well as I want/need to. Adjusting OAL for the specific load/rifle seems to be something that I need to spend more time on.

Maybe I'm off, but case length and bullet seating depth won't help with a head space gauge. On the case length, (for top consistancy and accuracy) I like to keep the cases as uniform as possible. If they are .010" difference in length, I don't think that's enough to matter, given all else is equal and consistant. Most chambers will allow about .010" over max case length before the brass is too long and making contact with the barrel at the case mouth. When I do trim my cases, I trim to suggested length, and that generally give me about .020" room to grow. To answer your question, I don't think a varying case length will increase/decrease your pressures enough to tell.

On bullet seating, you can seat the bullet to the book recommended length, and it will fit and function out of ALL rifles. If I have the rifle to chamber check the round, I will always seat the bullet out as close to the rifling as I can, and still function and feed out of the magazine. Some rifles, like a Browning A-bolt, have the shortest magazine box of any rifles. So, you can not seat the bullet very long in them, unless you single feed the round. So, select a bullet that is not seating depth sensitive (a tangent ogive bullet) for rifles like this. If you were to pick a Berger VLD in a Browning and fit it to mag length, you will have a difficult time getting it to shoot well, or as good as you could if you could seat it longer. There's just too much bullet jump. Seating the bullet out also gives you more room for a slower burning powder for max speeds. My 260 Rem comp loads with a 140 VLD, I was running a 2.910" OAL length, with a magazine max of length of 2.925" (modified AI mag, with the front rib removed). There was hardly any room to spare in the mag.

I am also new to reloading and am thankful for all of the useful info I have received here. In my reading I have read that bumping the shoulder .003-.005 on belted magnums really help w case life. I don't want to steal the thread but I hope this question is helpful; when I did this on a 7mag I'm working up I have found that the bolt is tighter to close than w factory ammo, is this expected or did I possibly do sumthing wrong in my fl sizing? I have not shot any of my test loads yet to see if there are signs of pressure but hopefully will get to this weekend.
I did all my measurements w the hornady headspace gauge as well.

Which die did you use to partial FL size?

This time I used an old Texan set after I loaded this set I bought an RCBS set to do the next set.