Homemade throat/land locating tool?

Use a dremel + thin wheel to cut the neck lengthwise on each side.

I read that guys using that method just use a fired case before it is resized.

Here is an article from Nosler:

https://www.nosler.com/blog/news-an...mine-proper-bullet-seating-depth-for-your-gun

Dave, there’s another method that I prefer. It works best with two people. I’ll try to outline it:

1. Buy a few 36” long dowels – a quarter inch diameter dowel will work great for 7mm and 30 caliber barrels.
   
   
2. Remove the bolt from your rifle.
   
   
3. Using your little finger, or a short piece of one of the dowels you bought if your finger is not long enough, push the bullet up into the chamber of your rifle until it contacts the lands.
   
   
4. Hold the bullet against the lands while carefully putting a dowel down the rifle’s barrel until the dowel is resting on the tip of the bullet.
   
   
5. Using a sharp pencil, make a mark around the dowel at the end of the rifle’s barrel. Be as precise as you can.
   
   
6. Remove the bullet from the chamber - you might have to give it a gentle nudge with the dowel.
   
   
7. Remove the dowel and re-install the rifle’s bolt.
   
   
8. Put the dowel back down the barrel until it is sitting on the face of the bolt.
   
   
9. Make another mark around the dowel at the end of the rifle’s barrel, again being as precise as you can.
   
   
10. Remove the dowel from the rifle’s barrel and measure the distance between the marks - I use a caliper. The distance between the marks is the OAL for that cartridge, using that bullet, seated so that it is contacting the lands in that rifle. It’s up to you how close to the lands you want to seat your bullets. I personally like a little clearance for my hunting rifles.
    

ATLDave said:

.308 Norma,

Thanks, that generally seems logical. Does that method work with secant-ogive bullets? Is there enough self-alignment to get basically the same jam-the-lands length every time with such bullets?

Click to expand...

You got me there Dave. It's going to take me a while to look up what "secant-ogive bullets" are.
I'll get back to you. Maybe someone else will chime in in the meantime.

ATLDave said:

http://www.accurateshooter.com/ballistics/tangent-vs-secant-vs-hybrid-ogive-bullets/

Supposedly, the secant ogives are more aerodynamic/lower-drag, but aren't as self-aligning in the throat.

But I only know what I read... I'm just getting into playing around with high-precision/long-range stuff.

Click to expand...

Thanks Dave.
OK, now I know the difference between secant ogive and tangent ogive bullets. Unfortunately, I don't know whether or not my method for finding the OAL for a cartridge with the bullet seated touching the lands will work with secant ogive bullets. I've never gotten into "high-precision/long-range" rifle shooting. I'm a hunter, and the tangent ogive bullets I've always used for hunting are plenty precise at the ranges I've used them.

GBExpat said:

Use a dremel + thin wheel to cut the neck lengthwise on each side.

Click to expand...

I've done it this way for decades. Make sure you get all the burrs off, inside and out. The hard part is getting the tension right on the bullet. If you happen to have a bushing die set you may be able to size it for a slip fit.

.308 Norma said:

Using a sharp pencil. . .

Click to expand...

The problem is that I want to measure ogive-to-lands contact to within a thou' or two, about 1/20th of your typical sharp pencil line.

I use a fired case, with just enough neck sizing to grip a bullet. Three repetitions within the requisite 0.002" range confirms you're seeing the actual contact measurement. You should strip the bolt in actions with a sprung extractor, but the fired case reduces that effect.

Fired case, pliers, pinch neck, making neck oval. insert bullet . chamber. Extract while keeping bullet from hitting receiver. The ejector is pushing it.

IMO GBExpat and 243winXP's methods are sound and mine only differs in that I use a set of neck-sizer bushings to achieve the same result. The only written material on this subject that I've seen personally is in the Lee reloading manual and it doesn't delve into ogives.

I have to set some of my reloads very short due to the ogive.
This is with a 9mm hand gun.
I run ~.010-.030 off the lands most of the time just depends.

I’ve been doing it for years by opening up the neck of a sized case with a round chainsaw file until the bullet is a slip fit. Takes 5 minutes. If you get a bullet stuck knock it out with an impact puller. I mark the modified case and keep it in the die box.

Ruger 15151 said:

I read that guys using that method just use a fired case before it is resized.

Here is an article from Nosler:

https://www.nosler.com/blog/news-an...mine-proper-bullet-seating-depth-for-your-gun

Click to expand...

Maybe. I tried that but wasn't really successful. The problem is that the expanded neck has essentially no tension if it has any at all. The method of using a sized case with a slit is much more user friendly.

Color the bullet with a sharpie or dykem if you have that. Then test & tune until you can see the rifling disturb the color on the bullet.

If you want to be precise about seating depth, this is pretty easy.



Generally I am an “off the lands” guy but it does help out on some firearms I have.

With any method of "push the bullet against the lands" I would suggest smoking (or otherwise coloring), and chambering a dummy round at the oal your inclined to use after you do your push test. That way youll know your out of the rifling.
Ive found it doesn' take alot of pressure to get a bullet a surprising ways into the rifling.
I use the cut neck after partial sizing method, you can change tension by just bending the neck halves in or out, and have found that im offten a ways into the lands if I don't reduce the tension a little.

GBExpat said:

Use a dremel + thin wheel to cut the neck lengthwise on each side.

Click to expand...

Me too

.308 Norma said:

Dave, there’s another method that I prefer. It works best with two people. I’ll try to outline it:

1. Buy a few 36” long dowels – a quarter inch diameter dowel will work great for 7mm and 30 caliber barrels.
   
   
2. Remove the bolt from your rifle.
   
   
3. Using your little finger, or a short piece of one of the dowels you bought if your finger is not long enough, push the bullet up into the chamber of your rifle until it contacts the lands.
   
   
4. Hold the bullet against the lands while carefully putting a dowel down the rifle’s barrel until the dowel is resting on the tip of the bullet.
   
   
5. Using a sharp pencil, make a mark around the dowel at the end of the rifle’s barrel. Be as precise as you can.
   
   
6. Remove the bullet from the chamber - you might have to give it a gentle nudge with the dowel.
   
   
7. Remove the dowel and re-install the rifle’s bolt.
   
   
8. Put the dowel back down the barrel until it is sitting on the face of the bolt.
   
   
9. Make another mark around the dowel at the end of the rifle’s barrel, again being as precise as you can.
   
   
10. Remove the dowel from the rifle’s barrel and measure the distance between the marks - I use a caliper. The distance between the marks is the OAL for that cartridge, using that bullet, seated so that it is contacting the lands in that rifle. It’s up to you how close to the lands you want to seat your bullets. I personally like a little clearance for my hunting rifles.

Click to expand...

You can cut the dowel to a length less than 6" longer than when placed in the barrel touching the bolt face.
Then you can measure what's sticking out with your caliper, instead of marking the dowel.

Edit: for an auto:
An easy method to determine OAL can be done using a Digital or Dial Caliper and a new pencil cut about one inch longer than the barrel.

With the barrel removed, put just a bullet into the chamber until it stops and hold it there.
Now put the cut pencil into the muzzle until it touches the bullet nose and measure the amount of pencil sticking out of the barrel.
Use the step feature on the BACK of the caliper and note the measurement.

Remove the bullet and re-assemble the barrel/gun.
Now put that same pencil into the muzzle until it touches the breech face and again measure the amount of pencil sticking out of the barrel.

The difference between the two measurements is the MAXIMUM overall length that will CHAMBER in THIS barrel/gun/bullet combination.
Use the back of the caliper like this to measure:

Uhmmm doesn’t anybody else use an OAL caliper like Hornadys? I used a split case once or twice before but if you want to accurately measure to the lands, get a gauge made for it.

Addendum; I see the OP was asking about homemade...but there are times to pay for good equipment and this is one I think.

edwardware said:

The problem is that I want to measure ogive-to-lands contact to within a thou' or two, about 1/20th of your typical sharp pencil line.

I use a fired case, with just enough neck sizing to grip a bullet. Three repetitions within the requisite 0.002" range confirms you're seeing the actual contact measurement. You should strip the bolt in actions with a sprung extractor, but the fired case reduces that effect.

Click to expand...

You can also score the dowel with a razor blade for a more precise measurement.

Uhmmm doesn’t anybody else use an OAL caliper like Hornadys? I used a split case once or twice before but if you want to accurately measure to the lands, get a gauge made for it.

Click to expand...

Like this one?



You don’t need to spend much money to duplicate the device but it’s even cheaper and just as accurate to use some of the methods mentioned in this thread.

Worth pointing out that this dimension can vary quite a bit sometimes, when seating to the lands.



This is a more consistent way to measure the area of contact as tip inconsistency doesn’t effect readings.