Jumping to the lands

Archeryrob said:

So we are back to a separate OAL for each rifle then. I am pretty sure I already fairly closely determined a separate OAL for her gun.

Also won't every guns lands be different than this comparator? I have two guns with different seating depths based on their lands. IMO, this comparator is only going to simulate a single set of lands.

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Your close, think of all this maybe like this.
Whichever bushing you use for the comp, the hole or bore ( is land diameter) that the bullet fits in, is the top of the lands ahead of the chamber and in front of the bullet seat and chamber proper. The bushing travels on the sliding part of the mike and simulates differences in how the angle of that leade is tapered and or formed. And it gives a repeatable reference point. Even if the bore of the comp bushing is smaller than the caliber. The bullet will slide in and out of the case at your will.

The chamber, between two different rifles of say the same caliber but different makes had differing tooling and wear variables possibly to make the lands interfere at differing points along its length with the ogive of a bullet because its a radius. The two chambers, may be exactly the same size and length, but its the area in front of the neck or bullets seat that needs to rapidly taper to bore diameter and cut the lands at the same time for bullet clearance. Its a cone shape with a short cylindrical section. And very important for quality of chambering.
The difference in diameter at the top of the lands is the OD of the neck of the cartridge, tapering rapidly to diameter of the depth of the grooves to the diameter of the bore and removing just enough of the lands on an inclined angle to allow the bullet to fit up in there without having to travel unsupported for as little as possible. And quickly seal the bore, nice and straight and make all the area thats not a case temporarily an extension of the case till the bullet moves forward and the neck is blown tight against the chamber making a seal.

Forget about overall length that includes the tip of the bullet to a certain extent. You could grind them off or clip with pliers and still get the same length measuring with the tool. Start thinking of measuring from the portion of the bullet that curves and transitions to its diameter, and the length of the case and where the bullet ogive measures up once you seat them.
Those tools with a couple of bushings will fit many rifles becuase they usually come in a set and very few if any identical rifles will have the same measurement at the lands because of production methods. As do, different makes of jacketed bullets including the cast ones we make ourselves becuase they have different forms.
What some people will do is make a dummy cartridge up, cut slots in the end of the neck to minimize tension but just have enough, seat a bullet, smoke the bullet with candle black and then fit the bullet in the neck at just the point you can see the smudge removed from the blackened bullet where it contacts the lands. And maybe back off a little for errors in case length or methods of consistency when bulleting a case and or loading.

AlBeight said:

I have no intelligent opinion on this matter, and only a minimal understanding of the topic, but I came across this video on YouTube by Eric Cortina. He’s a very well regarded champion long range and bench rest shooter. I just thought this video might help your decision(s). Not only does he not recommend doing it, but he calls it “stupid”, that seems pretty definitive.

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Pretty good and here's a thing, Its cheaper to just switch the barrel than keep buying or making ammunition.
Makes me think as well, the other day a poster talked about our grandfathers worrying about cleaning potassium primer residue to protect the bores of their Springfield and Garand rifles and shooting all ten's and X's.
Their uncle, already knew what I wrote above because he shot machine guns with the same ammo over their fathers heads as they advanced. So they gauged the throat and not the muzzle or the bore.

Archeryrob said:

So we are back to a separate OAL for each rifle then. I am pretty sure I already fairly closely determined a separate OAL for her gun.

Also won't every guns lands be different than this comparator? I have two guns with different seating depths based on their lands. IMO, this comparator is only going to simulate a single set of lands.

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No the comparator is what measures the lands for your guns and yes every gun is different this will work infintely if you have 9 30-06’s if will work with all 9 and tons of other calibers if you get the set and will work on AR platforms if you get the curved one.

Doco Overboard said:

Forget about overall length that includes the tip of the bullet to a certain extent. You could grind them off or clip with pliers and still get the same length measuring with the tool. Start thinking of measuring from the portion of the bullet that curves and transitions to its diameter, and the length of the case and where the bullet ogive measures up once you seat them.

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I understand this, but what is it call as it is not COAL or OAL. Ogive length?

Doco Overboard said:

What some people will do is make a dummy cartridge up, cut slots in the end of the neck to minimize tension but just have enough, seat a bullet, smoke the bullet with candle black and then fit the bullet in the neck at just the point you can see the smudge removed from the blackened bullet where it contacts the lands. And maybe back off a little for errors in case length or methods of consistency when bulleting a case and or loading.

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Yes and about my method now.

deerassassin22 said:

No the comparator is what measures the lands for your guns and yes every gun is different this will work infintely if you have 9 30-06’s if will work with all 9 and tons of other calibers if you get the set and will work on AR platforms if you get the curved one.

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Oh boy, lots more tools to buy and their special modified cases. And a special one for a lever or pump action. $40 for each of the two lands measurers, $10 for each modified case, $60 for the ogive comparator. That is a lot of stuff to about do the same thing Doco explained I am doing with dummy round fitting.

Archeryrob said:

I understand this, but what is it call as it is not COAL or OAL. Ogive length?

Yes and about my method now.


Oh boy, lots more tools to buy and their special modified cases. And a special one for a lever or pump action. $40 for each of the two lands measurers, $10 for each modified case, $60 for the ogive comparator. That is a lot of stuff to about do the same thing Doco explained I am doing with dummy round fitting.

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It’s 38.00 for 7calibers and the holder and then the rods and case yes but you buy it one time and you have it for a lifetime for numerous calibers you can also make your own if you have a tap and die set. It boils down to how much you value your face and components and time trying to figure it out. And it’s called base to give length COAL don’t really matter if your chasing the lands. It will come into play as COAL for mags in most cases.

Archeryrob said:

I understand this, but what is it call as it is not COAL or OAL. Ogive length?

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A maximum cartridge.
And thats the thing with all of this. Manufacturers need to accommodate minimum cartridges in maximum chambers and maximum cartridges in minimum chambers but hand-loaders or cartridge builders dont have to do that.
A person could think of the whole ordeal like headspace for the cartridge case and then another range for the cartridge with one of its components, that one being the bullet often the powder and then combine them.
What makes limitations is, length of the neck, length of the magazine,length of the leade and then the bullet thats selected.
Sometimes for maximum cartridges and very often they need to be single loaded.

I ordered the straight land measurer, the micrometer bullet measurer and I found the tap and die for shells all on Amazon. I had points to save on the wife complaining. I got a 18 x 29 shed going up soon and still buying stone topsoil and gras seed. No more gas on the fire

deerassassin22 said:

This will help you identify where your lands are for a given bullet. So every type you switch bullets you should do this so you know how far your jumping your bullets to the lands. This will also give you your base to OGIVE measurement which is more accurate then your COAL due to the fact that COAL various based on the bullet tipping process and type of bullet.

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I use this type of comparator and works very well.

Okay, so I bought the Bullet Comparator set. Part # B14 and it lists below as the bullet types. The instruction don't explain which insert is for which number. I looked on their website for the part and don't see a chart.

The inserts have number like shown below. IMO, once you get to 6 they don't make sense any longer. [EDIT] my assumption of guesses here is wildly wrong!!
1-17 Assuming .172
2-22 .204?
3-24 .224?
4-25 .243?
5-26 .257?
6-27 .264? (6.5mm)
7-28 .278?
9-33 .284?
10-35 .308?
11-37 .338?
12-45 .375?
13-41 .416?
14-20 .458?

The Complete Set (B14) includes these inserts: .172, .204, .224 (5.56mm), .243 (6mm), .257, .264 (6.5mm), .277, .284 (7mm), .308, .338, .358, .375, .416, .458.

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NM, I found the parts list and the number are the part numbers. They don't include that in the packaging so you can tell which one to use. They should have included a chart

1-17 .17 cal

14-20 .204 cal

2-22 .224/5.56mm

3-24 .243/6mm

4-25 .257 Cal

5-26 6.5mm

6-27 277 cal

7-28 .284 cal/7mm

8-30 .308 7.62mm/8mm

9-33 .338

10-35 .358 cal

11-37 .375 cal

13-41 .416 cal

12-45 .485 cal

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Have you all drilled and taped fired cases? Or I have to buy the Hornady cases?

I bought the drill and tap but my 30-06 bullets and 6.8 bullets don't size sized bullets in and out of the freely to work with this to check the chamber.

EDIT - Damn looks like you have to order their brass to get the neck widened or send your fired bass to them. Then why would they sell the drill and tap kit?

Ordered 30-06, 30-30 and 6.8 SPC from Midway.

Hornady is like Snap-On for reloaders

I am becoming frustrated with this. I ordered the 30-06, 30-30 and 6.8 cases from Midway and they got delivered. The necks on the modified cases are just as tight as all other cases and the bullet does not slip in it. I measured a bullet at .309 and the gas check won;t even slide in. It would seat with a press, but that is not the point of this. It is supposed to slide back and forth easily. Do I need to have another tool to spread the necks a little?

Archeryrob said:

I am becoming frustrated with this. I ordered the 30-06, 30-30 and 6.8 cases from Midway and they got delivered. The necks on the modified cases are just as tight as all other cases and the bullet does not slip in it. I measured a bullet at .309 and the gas check won;t even slide in. It would seat with a press, but that is not the point of this. It is supposed to slide back and forth easily. Do I need to have another tool to spread the necks a little?

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Any chance you have a few cases fired in each gun but otherwise untouched?

Of course, but the bullets don't slide is them either.

Archeryrob said:

Of course, but the bullets don't slide is them either.

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That's odd. Bullets should go right into fired cases. Your chambers are factory.

In one of my guns, the necks must he turned to fit and the neck clearance is tight enough that fired cases spring back to bullet nominal. There are no factory chambers cut this way.

I'll check them all again later on. Sized .278 and .309 bullets are not sliding into my fire cases or the hornady cases.

Archeryrob said:

I'll check them all again later on. Sized .278 and .309 bullets are not sliding into my fire cases or the hornady cases.

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Hmmm....are the case mouths tighter than the rest of the neck? Measure OD at NSJ, mid neck, and mouth to determine. Seen this happen with repeated firings and no annealing.

Okay, got my micrometer to my desk

30-06
Hornady case neck .306 - Wont take the bullet
Fire brass from my rifle - .3075 .304 .307 .305 .3055 .307 .309 The bold ones will take a bullet in the neck, but bounce on the lube grooves. Its like the crimp edge did not relax. Normal test will not take the bullet

6.8 SPC
Hornady case .278 and takes the bullet, but does not slide easy. Hangs up a lot on the lube grooves
Fired brass from my rifle - ..279(5) ..279 . 278 . 277 The first one goes in easily, but has a slight grab were the crimp still grabs at it, but work way better than the 30-06. Second in by tight and hard to use. last two not really, needs force and gas check get stuck in them.
I for some factory cases from Sellier and Bellot and most case mouths are dinged enough to be unusable for this without sizing. Measures the same thickness but Starline seems tougher and none of those are bent.

30-30
Hornady case take the .309 bullet fine, measures .309 and some times .310

It seems I will get to use the drill and tap I bought to modify cases. 1 Hornady modifed case is unacceptable, 2 work, but the 6.8 still could need a slight mouth reaming to work great. I could stop short from how tight it feels. 30-30 case is perfect and only hangs when the gas check gets to the mouth and it would never get that far in the chamber unless fired.

So I plan to drill and tap a 6.8 I tested for a better case and a 30-06 I found to work way better than the Hornady case. I need a slight reamer for the case mouth to open the crimp edge.

Sounds like the case mouths are the issue. I'll root around and see if I can find some 308 and 3006 cases that are annealed. Load em, do not crimp em, fire em, then modify with L drill bit and your tap.