Measuring Chamber and Cartridge for OAL Length

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Which tools does one require to accurately and repeatably determine the loaded cartridge OAL (edit: seating depth ?) to engage the rifling ? I have a micrometer and caliper.......

Confused by the Sinclair and Hornady websites. There are bodies, bases and inserts. I don't need a kit with 14 inserts that I will never use.

Both show a comparator, but it doesn't look like image I have of the Hornady tool. My vision is a tool that holds a bullet and fits in the chamber, bolt removed. The tool is lengthened until contact is made in the rifling by the bullet. The measurement is made off the caliper. The resulting measurement can be used to "jam" or seat off the lands. The comparators I have looked at appear to be for measuring a cartridge from base to ogive......

Right now I simply ease back on the neck sizing collet die for a loose bullet fit and chamber it to push the bullet back into the case......

Am I confusing two separate operations and tools ? The one (s) I want is to determine where my loaded bullet is relative to the rifling.

Thanks !!

http://www.hornady.com/store/Bullet-Comparator-Inserts

http://www.sinclairintl.com/.aspx/pid=35491/Product/Sinclair_Bullet_Seating_Depth_Tool

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These don't appear to be suitable for the purpose I have described. Am I missing something ????
 
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First off, the OAL of a cartridge has nothing to do with where the bullet engages the lands. You don't really find benchrest shooters talking about OAL.

The second thing is what I'd call "trusting your tooling and components." Seating dies that work off the end of the bullet assume the bullets all have the same length from base/beginning of the ogive to point. Depends of how closely you want to measure "same." So you can get/make seating dies that pick up the bullet closer to the point where the bullet will engage the rifling. But then, how to get measuring apparatus that will check? Etc.

What I'd really suggest is a good book that goes through each stage, and what it means. That way, you can think through the compromises, because there will be some. On the internet, or a website, things get skipped. Kind of like one of those humorous assembly instruction sheets "Do A, then B, then C, but first . . ."

When I started out, one of the best books was Sinclair's Precision Reloading and Shooting Handbook -- probably no longer in print; maybe someone can give a current title.

* * *

To try & get at what I'm talking about, remember in the 1890s, there was a belief that no breechloader would ever shoot with a muzzle loader, where a paper patched bullet was loaded using a false muzzle. The latter gave 100% loading density, a bullet perfectly centered in the bore, rifling engagement that was always even, etc. Then came jacketed bullets . . .

Viewed one, way, all we're trying to do is to get back to the level of precision that came easily with the accuracy-oriented muzzle loader.
 
?

Charles, thanks for responding. Let me re-phrase the question, since the websites that offer the tools do not. I hope it doesn't take a book. Can someone explain how and with what to measure and set up a new or different bullet to either engage, jam, or lay off the rifling ?

Thanks.

I'll check phone with Hornady tomorrow but it's hard, nay, near impossible from work, and I am on PST.
 
It doesn't take a book and you don't need gadgets either. you can do it with a cleaning rod and some masking tape add a pencil. OAL is the starting point. after that you add or subtract from that measurement to find the sweet spots.
Here;s how. remove the firing fin from the bolt. run a clening rod down the bore.place a small mark where it ends at the muzzel. put a piece of paper tape {masking] on the cleaning rod ahead of the small mark.
pull the bolt out place the bullet of your choice in the chamber and hold it there with a dowel or small rod.
run the cleaning rod down until it hits the bullets nose. Mark the rod again at the muzzel. you now have 2 marks on the rod. measure the distance with your caliper, you now have the touch or slight jam for that bullet. if you change bullet shapes
you do it again to confirm OAL.
 
The problem with recipes is they don't make you a cook, or so my grandmother use to say. If you don't have a good concept of what's going on, all you have is a number, which might or might not be useful.

When I say "just touching" I mean "just touching hard enough to make a mark on the bullet." That's some odd distance beyond "just touching" as determined with the Stoney Point or cleaning rod method. so when SOME GUY at the range SAYS "they shoot best just touching" or some number plus/minus from that, I have to remember his starting point may be different than mine. Of course, I've already discounted him, because he forgot to mention that was in his barrel, with his load.

Well, if I were the only person using "just touching" in the sense of "just touching hard enough to make a mark," I'd be an oddity. But I'm not. Most (dare I say all?) of the benchrest shooters I know use the words just that way.

Point two. OK, now you have a number for "just touching," regardless of the details. Now what? As long as you take this point you've just determined as an arbitrary starting point, signifying nothing else, and to be rechecked as the barrel's throat erodes, you're OK.

That's what books are good for. When you have the concept, you learn faster. And it costs less.
 
Charles I have always started with the bullet jammed, with a dummy round, I measure that four times then i find out how far it is until there are no more marks and write that down, then every once in a while check to see what has changed. Tried chasing lands once or two million times and in more times than not had to go back to the same OAL. to get it to shoot again. I know of one guy a top shooter that throated his rifle because the bullets were in the case to fare and still had to go back to his original OAL. might be a good subject!

Joe Salt
 
You're right, Joe. I have had several barrels where the eroding lands seemed to make no impact on the best amount to jam the bullet. And several the other way, too, where you had to chase the lands. Just one more reason to avoid the recipe approach!

The other thing people seem to forget is that it doesn't matter what "people" like, it's what the rifle (barrel) likes.
 
Thank You Charles It is what the Barrel likes. That is why if they don't shoot cut them off and try again, or get a new one.

Joe Salt
 
The reason there is so much potentially confusing information on determining lands distance and seating depth is that there are actually a lot of ways to do it properly.

There are specialist tools like the sinclair and the hornady units but there are other means like the cleaning rod down the muzzle and the split or partially neck sized case that work just as well. You just need to decide which one fits your needs and budget.

But the one thing you will need right from the start is a good comparator like these
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Personally I use split cases and measure them using my comparator. I find the cleaning rod method unreliable due to the inability to accurately determine the point it comes out of the muzzle due to crown shape.
split_cases.jpg

comparitor_in_use.jpg

I then use the same comparator when setting up my seater die which means I'm not having to calculate in the variations from one tool to the next.
 
Close - Gizmo

If you don't have a good concept of what's going on, all you have is a number, which might or might not be useful.
Click to expand...

That's the discussion I was trying to get. :eek:

One man, one weapon, one bullet, one load. Simple. Constant.

The bullet can be set at depth A, B, or C. A is off the lands, B touches, and C is jammed. Each variable has a unique repeatable value, a measured distance with this gizmo. It will also have a different and unique OAL. Actually there are sub variables A1, A2, A3, and so forth each being A plus a Different distance from B.

One of these values with these variables and constants makes the most consistent pressure with this weapon and therefore the smallest group when shot at 100 yards.

I have reduced the variables to OAL, or seating depth. I can change the seating depth with my die and press. I have shot over 200 rounds at my existing OAL and powder load. Same brass. Same box of 1,000 federal match primers. As long as the constants are held constant, and the variable is seating depth, I disagree that OAL doesn't have anything to do with where the bullet touches the rifling. It doesn't define it, but it affects it. Sort of a symbiosis. One begat the other. Yin and Yang. You can't change OAL and not change seating depth or distance from the rifling.

I'm seeking the knowledge of Gizmo, the operation. :eek:
 
Let me take a minute to point out that there are two uses of the word jam, as it relates to the seating depth of bullets.

It is my belief that the initial (and to me more proper) came from Benchrest competitors, and was/is the name of the loaded length of a round that is at the maximum that will not result in the bullet being pushed into case by any amount, as it is chambered, and the action is closed. This is done with the neck tension that will be used for actual loading, and the length will vary with it. It is a specific length that once established is used as a reference. One might say that he is so many thousandths off jam. This system generally ignores the point where a bullet touches. Indeed, shooters may tell you that they are .050 off jam, when jam is only .020 longer than touch.

The other use of jam, it think has come along later, and stems from a lack of any readily available reference that teaches what is to me the more proper use of the term. This is where reloaders talk of being jammed a certain distance into the rifling, meaning that amount beyond where the bullet would be touching the rifling. Given that it is a definition that seems to have come along later, I find its use somewhat grating to my ear, sort of like when someone uses ain't for isn't. To me, it would sound better, and be more proper if shooters, that are referencing their loaded length from the point where the bullet would touch the lands, would say that they are jumping their bullets a certain distance, touching, or loading a certain distance longer than touch, or some distance into the rifling. For example, I seat most of my .22 caliber varmint bullets somewhere from .006 to .010 into the rifling.

One might ask what what my reference is to make claims about the order in which these usages have come to pass. For me, the earlier usage was defined, many years ago, in the old black and white issues of Precision Shooting, when it was more narrowly focused on the various forms of Benchrest competition, and had not yet become a full time occupation for the editor.

I know that readers of internet shooting sites are at many different levels of experience, and that we have all come to use words that relate to it based on what we have read an/or heard, so I do not delude myself that an explanation of this sort will have much effect, but nevertheless I think that it is worthwhile mentioning.
 
Just stay away from that hornady device with the cases. It will not give you accurate readings unless you fireform and tap your own cases...and that is the long road. All you need is the Sinclair nut and a set of calipers.....mission accomplished.

Hovis
 
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