I feel like I'm in a forest

[PWC]

and can't recognize a tree. I'm thinking and maybe I've got my tongue over my eye tooth and can't see what I'm saying......

You need to know COAL to make sure a cartridge will fit the magazine. OK Expecting a consistent number in thousandths for base to tip is unlikely.

Loading manuals list the COAL. Is that the same as above, + or -, or is it base to ogive for the specific bullet?

I F/L size, and seat to the groove, if applicable, and seat to the dummy round with a bullet of the same weight, with no groove.

Is base to ogive really only for bullet to lands relation?

Please point out the tree.

 

[ms6852]

You are confusing CBTO (Cartridge Base to Bullet Ogive). When you measure in this manner from the base of the cartridge to the ogive the length will be different than when you measure that same cartridge from the base of the cartridge to the tip of the bullet. Measuring from the base of the bullet to the tip is what gives you the cartridge overall length.

On a same caliber round for example, the cartridge overall length will differ depending on the weight of the projectile you are using. The reason for that is that for the weight of the bullet to go from say, for example, from 150 grains to 180 grains and for the bullet to maintain the same diameter say 30 caliber the 150 grain bullet is shorter than the 180 grain bullet. Increasing the length of the bullets increases its weight. So depending on your chamber and the bullet weight you are using maintaining a minimum and a maximum coal is important so that the round can be chambered. Exceeding coal will not allow you to chamber a round, regardless of pistol or rifle.

 

[jmorris]

Think of it like this. The “plunk” test is testing to see not only that the round fits the chamber but also that the projectile is seated deep enough that it does not contact the rifling.

A case gauge is generally “under” or smaller than a given chamber in that caliber but has no rifling to contact.

A round that passes a “plunk” won’t necessarily pass a case gauge and one that passes a case gauge alone won’t necessarily pass a “plunk” test.

There is a tolerance, in thousandths, you are capable of loading ammunition to.

If you have good components it can be very tight, maybe even tenths of thousandths +/-.

Just like “max case length” and “trim to length”, you have a “max caol” and a length you will load to that your (+’s) don’t go over.

You can make rounds “under” what will still plunk and they will still plunk. Make them over and they don’t. You have to move your target OAL to a point where your “over” rounds are still “under” not being able to plunk.

If you have a combination that will plunk at 1.000” but no more but your OAL variation with the components and tools you are using to put them together drops out them with a .010” variation, it would make sense to use a shorter number, like .990 for example (-0.000/+ 0.010 would still plunk). That way the longest of them will still not be shoved into the rifling.

 

[CQB45ACP]

Think of it like this. The “plunk” test is testing to see not only that the round fits the chamber but also that the projectile is seated deep enough that it does not contact the rifling.

A case gauge is generally “under” or smaller than a given chamber in that caliber but has no rifling to contact.

A round that passes a “plunk” won’t necessarily pass a case gauge and one that passes a case gauge alone won’t necessarily pass a “plunk” test.

There is a tolerance, in thousandths, you are capable of loading ammunition to.

If you have good components it can be very tight, maybes even tenths of thousandths +/-.

Just like “max case length” and “trim to length”, you have a “max caol” and a length you will load to that your (+’s) don’t go over.

You can make rounds “under” what will still plunk and they will still plunk. Make them over and they don’t. You have to move your target OAL to a point where your “over” rounds are still “under” not being able to plunk.

If you have a combination that will plunk at 1.000” but no more but your OAL variation with the components and tools you are using to put them together drops out them with a .010” variation, it would make sense to a shorter number, like .990 for example. That way the longest of them will still not be shoved into the rifling.

Most of this is way over my head but I do believe this is a real life example of what you’re saying:

I have four semi-custom 45ACP 1911s and Hornady & RCBS case gauges and a TE Wilson cartridge gauge. One particular brand name .452 coated bullet in any brand case using a minimum or maximum taper crimp will pass all three gauges but will plunk in just ONE of the pistols.

I have adjusted the COAL. I test all cases in one or more gauges after sizing. I can cram loaded cartridges through a Lee FCD or even bulge bust them all the way through. And I have run the bullets through a .452 sizer. But after all that they still will only plunk in the same ONE pistol. (If I had a .451 sizer I’d try that too. Bullet maker said fine.)

It would thus appear to be a case length issue but no matter, the results are always the same. My particular solution is shoot what I’ve got through that one pistol but never buy that bullet again.

 

[GW Staar]

Many years ago we didn't have the OAL gauges to help with this. (unless we had them made in a machine shop) We had to partially size a case so that a new bullet would be held just enough that it would slide "barely". We would "seat" the bullet we wanted to use, long.......then carefully load it into the chamber and lock the action. Then slowly, carefully eject, so that the OAL wouldn't move. That provided us with an OAL that touched the grooves.

Once we had that we could set our seater to seat a particular distance from the grooves.

Next step was to place the cartridge next to the magazine.....to see if and how much we needed to seat deeper to allow them to fit into the magazine. I have a few OAL and Ogive to base gauges, RCBS, Hornady, Wilson. They all have their uses, and are worth buying, and they save time, but each rifle is different.....often you still have to do the above.

For rifle, Hornady makes special cases for theirs....worth while tool. But if you have an odd less popular caliber, you are back to doing it the old way....or make your own "special" case that will screw on the the tool. I did that for my 22-243 Middlestead.

 

[CQB45ACP]

Many years ago we didn't have the OAL gauges to help with this. (unless we had them made in a machine shop) We had to partially size a case so that a new bullet would be held just enough that it would slide "barely". We would "seat" the bullet we wanted to use, long.......then carefully load it into the chamber and lock the action. The slowly, carefully eject, so that the OAL wouldn't move. That provided us with an OAL that touched the grooves.

Once we had that we could set our seater to seat a particular distance from the grooves.

Next step was to place the cartridge next to the magazine.....to see if and how much we needed to seat deeper to allow them to fit into the magazine. I have a few OAL and Ogive to base gauges, RCBS, Hornady, Wilson. They all have their uses, and are worth buying, and they save time, but each rifle is different.....often you still have to do the above. Hornady makes special cases for theirs....worth while tool. But if you have an odd less popular caliber, you are back to doing it the old way....or make your own "special" case that will screw on the the tool.

Good grief! Is this how you spent that cold Valley Forge winter with ole George?

 

[GW Staar]

No, that was black powder firearms.....muzzle loaders. Can't help you with that. Just trying to cut down a few trees in that forest, so the OP can see better. Never met George, tho I would have been honored to.

 

[jmorris]

A gauge has no rifling to contact unless you made a perfect one off a piece of barrel using the reamer that cut the chamber; however, I use them because they can check parts of the case a “plunk” cannot. Like the base/rim.



I plunked for some time before I learned the benefits of a case gauge, probably wouldn’t have ever started if it wasn’t for competitive shooting and the high price malfunctions cost while the clock is ticking.


I believe the OP’s question is concerning length and interference. It’s one of those topics that is easier to discuss with all of the information (that we don’t have) but here is one example of not just using an OAL dimension to get desired results (ammo that runs).

Precision calls their swaged 230 grain bullet a “round nose” but it has a flat spot on the tip.



If I have a pistol that needs this length for a regular 230.



I have to load David’s bullets to,



The “why” is easier to see if we use a “datum” (A arbitrary diameter along the ogive of the bullet). In this case (no pun intended) a spent 9mm.




If I load them to the same OAL, the ogive of the blunt bullet causes chambering issues, load to the same datum measurement and everyone is happy.

 

[GeoDudeFlorida]

Many years ago we didn't have the OAL gauges to help with this. (unless we had them made in a machine shop) We had to partially size a case so that a new bullet would be held just enough that it would slide "barely". We would "seat" the bullet we wanted to use, long.......then carefully load it into the chamber and lock the action. Then slowly, carefully eject, so that the OAL wouldn't move. That provided us with an OAL that touched the grooves.

Once we had that we could set our seater to seat a particular distance from the grooves.

Next step was to place the cartridge next to the magazine.....to see if and how much we needed to seat deeper to allow them to fit into the magazine. I have a few OAL and Ogive to base gauges, RCBS, Hornady, Wilson. They all have their uses, and are worth buying, and they save time, but each rifle is different.....often you still have to do the above.

For rifle, Hornady makes special cases for theirs....worth while tool. But if you have an odd less popular caliber, you are back to doing it the old way....or make your own "special" case that will screw on the the tool.

I never did it that way. I was taught to clear the action and disassemble so the chamber was accessible. Mount the gun chamber up, drop in a bullet, use a depth mic’ to measure from the chamber mouth (or some other solid point) down to the base of the bullet. Then replace the bullet with a sized case and measure to the case head. Use a little math to get the max overall length cbto for that bullet in that chamber. Then subtract desired leade jump, necessary mag fit, minimum and maximum seating depth, case fill at each seating depth, and other useful measures. It’s pretty easy and you only have to do it once for each bullet/chamber combo. The case dimensions should be constant. Only have to measure chamber rim to base once.

 

[BBarn]

Loading manuals list the COAL. Is that the same as above, + or -

YES

Is base to ogive really only for bullet to lands relation?

YES

As bullet nose profiles change, the difference between COAL and base to ogive measurements also changes.

 

[GW Staar]

This is interesting....Jmorris assumed pistol.....I assumed rifle. (He did mention "full length resizing.") Anyway I do like jmorris's 9mm trick.....never thought of doing that for pistol.

GeoDude's a method too, more trees, but still useful. The O.P. still has to cut down some trees to see. .......thinking we just added more?

 

[CQB45ACP]

All you guys sound like real pros. I’m just too old to learn it and that’s presuming I even have the intellect to do so.

 

[higgite]

GeoDude's a method too, more trees, but still useful. The O.P. still has to cut down some trees to see. .......thinking we just added more?

Rather than adding more trees to OP's forest, I suspect this thread may have just highlighted some that were already there but he couldn't see before.

 

[CQB45ACP]

Rather than adding more trees to OP's forest, I suspect this thread may have just highlighted some that were already there but he couldn't see before.

If a tree appears in the forest is there a reloader there to see it? If there is a tree?

I think you all have explained what anyone would ever need to know even if they didn’t know it at first.

 

[mdi]

You need to know COAL to make sure a cartridge will fit the magazine. OK Expecting a consistent number in thousandths for base to tip is unlikely.

Don't really understand what you mean. With decent bullets I can keep OAL variation to under .005". In my semi-auto reloading the OAL is determined by the bullet manufacturer's bullet shape/design and listed in the reloading manuals I use, for good chambering, so magazine fit is secondary (in all my semi-auto reloading, magazine fit has come into play with good plunking handloads in only gun. My 45 ACP handloads fit my 1911 and Ruger P90 chambers and magazines easily, but my HP carbine needs the same handload seated .010" deeper to fit the magazine (one gun out of 14 semi-autos I reload for).

One example of OAL determined by bullet shape Is Lee's 452 228 1R and 452 230 2R. Both 45 cal round nose 228/230 grain bullets but the OAL for the 1R is much shorter because of the "fat, blunt" shape...

 

[PWC]

Don't really understand what you mean .

Even with $$$ competition bullets there is bullet length variation, just as BBarn said, "As bullet nose profiles change, the difference between COAL and base to ogive measurements also changes."

My question came from being too close to my answer causing me to doubt myself. I was thinking about rifle when I asked. I use the "poor man's comparator" as JMorris shows (best and clearest explanation by pics I've ever seen!).

 

[BushMaster-15]

I've never known a single case ,pun intended ,which didn't pass the plunk test ; which was commercially manufactured . There is a REASON for that ,it's known as Specification as in Standards SAAMI to be exact . Custom chambering being somewhat an exception ,as generally extending a throats leade aka free bore allows longer bullets to be chambered ,before contacting the rifling lands . Which is more common for Bench Resters .

Different bullets round nose flat nose CAN'T be made to the same OAL ,they WON'T chamber . Try a 9mm Round nose at COAL and a Berry's FNHP and You will instantly grasp the problem and how to correct it .

https://saami.org/technical-information/ansi-saami-standards/

 

[uuolf]

Think of it like this. The “plunk” test is testing to see not only that the round fits the chamber but also that the projectile is seated deep enough that it does not contact the rifling.

A case gauge is generally “under” or smaller than a given chamber in that caliber but has no rifling to contact.

A round that passes a “plunk” won’t necessarily pass a case gauge and one that passes a case gauge alone won’t necessarily pass a “plunk” test.

There is a tolerance, in thousandths, you are capable of loading ammunition to.

If you have good components it can be very tight, maybe even tenths of thousandths +/-.

Just like “max case length” and “trim to length”, you have a “max caol” and a length you will load to that your (+’s) don’t go over.

You can make rounds “under” what will still plunk and they will still plunk. Make them over and they don’t. You have to move your target OAL to a point where your “over” rounds are still “under” not being able to plunk.

If you have a combination that will plunk at 1.000” but no more but your OAL variation with the components and tools you are using to put them together drops out them with a .010” variation, it would make sense to use a shorter number, like .990 for example (-0.000/+ 0.010 would still plunk). That way the longest of them wil

What he said...

 

[gwpercle]

You're over thinking it .
When OAL or COAL is listed in a loading manual for a particular bullet the measurement is from stem to stern ... cartridge case base to end of projectile nose , the over all length of the round ... No consideration given or taken for ogives ,

The ogive measurements are used when you are working out the dimension to seating off the lands .

Seat to the crimp groove or cannelure when possible ... that is usually a good if not the best place to be and if when seated in the crimp groove or cannelure the OAL is not the deminsion given in the book ... don't worry about it ... give it a try ... usually the crimp groove will not steer you wrong unless the bullet is not made to be used in that cartridge ,
Gary

 

[jmorris]

My question came from being too close to my answer causing me to doubt myself. I was thinking about rifle when I asked. I use the "poor man's comparator" as JMorris shows (best and clearest explanation by pics I've ever seen!).

Your post is in, your quote of his post.

Checking your work is never a bad idea, the more dangerous things get the more it’s OK to not become complacent.

They say a picture is worth a 1000 words, they are even better in some cases.

For rifle, the same concept of your longest “over” has to still fit. Even with “good” bullets, like these SMKs, base to tip is going to change because of inconsistencies in the bullets themselves, so I don’t worry about OAL to the .001 if the bullets are +/- .002. Even if you did seat them (all to different depths) to achieve the same OAL, that would be counter productive to the goal of accuracy.



But similar to the blunt nose vs rounded pistol bullet example an ogive measurement is the same. You don’t even need to break the bake to test that, just remove your seating stem and use it.



If they are all the same and the longest OAL of them fits the mag, carry on.

 

[mdi]

I may be just "old and slow", but I'm hearing confusion between COL and "Base to Ogive". Bullet lengths variation and case length variations have very little to do with COL/BTO (base to ogive) variations...

 

[PWC]

I have got my answer, thanks all. Mods, you can close if you want.

 

[Mal H]

Closed at the request of the OP.