measuring OAL

[timbo]

I was at Cabela's the other day and saw their 30 dollar oal gauge hanging there...I've been starting to think "accuracy" in my reloading, especially with .223.
I've read that setting correct oal (leade) is critical to accuracy. I almost sprung for it and then realized there might be a less expensive way to attain the same thing
so I came up with this idea...split the neck of the case, put the bullet into the case part way, push it into the chamber until the case sits fully, carefully pull it out and then measure the OAL.
Subtract a few thousandths (20 maybe) and then set the bullet seating die for that...thoughts? Will it work OK for what I'm trying to do?

 

[EddieCoyle]

In theory, that would work, but there are a number of problems with it. First, you're likely to stick the bullet in the lands and pull out an empty case.

Second, how will you measure it accurately? What if the bullet tips are slightly different?

 

[EddieCoyle]

The old-school way to do it is to load a bunch of dummy rounds at various seating depths, 'smoke' the bullet with a candle flame, stuff it in there, and look for marks from the lands.

You still need a way to measure it though.

 

[daddysuperfly]

The old-schol way to do it is to load a bunch of dummy rounds at various seating depths, 'smoke' the bullet with a candle flame, stuff it in there, and look for marks from the lands.

You still need a way to measure it though.

and what is the 'prefered' depth? should there not be any marks on the bullet?

wouldn't calipers work for measuring?

 

[timbo]

Good questions...The stuck bullet might happen but it could easily be pushed out if that happens...as far as the bullet tips being different (I'm assuming you are talking about the different ogives on different bullets)...Is there that much of a difference on a batch of the same bullets? The OAL gauge I saw at Cabelas is a rod sliding inside a tube with the tube screwed onto the base of a modified case...put a bullet into the slightly oversized neck (.002 larger I think) and then slide the whole thing into the chamber and seat it. Push the rod which pushes the bullet up against the lands and then pull the whole thing out. Again, it seems to be a working idea but I think even with the Cabela's tool, you could still get the bullet stuck and you would still have different bullet sets, depending on the ogive of the different bullets...does this make sense???

linky to the gauge at Cabela's: http://www.cabelas.com/product/Shoo...Rprd731927&WTz_l=SBC;BRprd731927;cat104635080

 

[EddieCoyle]

Good questions...The stuck bullet might happen but it could easily be pushed out if that happens...as far as the bullet tips being different (I'm assuming you are talking about the different ogives on different bullets)...Is there that much of a difference on a batch of the same bullets? The OAL gauge I saw at Cabelas is a rod sliding inside a tube with the tube screwed onto the base of a modified case...put a bullet into the slightly oversized neck (.002 larger I think) and then slide the whole thing into the chamber and seat it. Push the rod which pushes the bullet up against the lands and then pull the whole thing out. Again, it seems to be a working idea but I think even with the Cabela's tool, you could still get the bullet stuck and you would still have different bullet sets, depending on the ogive of the different bullets...does this make sense???

linky to the gauge at Cabela's: http://www.cabelas.com/product/Shoo...Rprd731927&WTz_l=SBC;BRprd731927;cat104635080

OK. Say the bullet sticks in the rifling (which it will). How do you measure it with your version?

Poke it out, insert it back into the case and, what? The whole idea behind the Hornady (it used to be the Stoney Point) gage is to slide the rod up, lock it in place, poke the bullet out of the rifling, stuff it back into the gage/modified case so that the bullet bottoms out on the rod, and measure it with a bullet comparator (Google Hornady Bullet Comparator).

When I say 'bullet tips' I mean literally, the tips of the bullets. If you measure OAL from the case head to the tip of the bullet, what if the tip is slightly deformed? Let's say that you have a box of 100 bullets, and the tips vary by 0.005". How are you going to measure the OAL of your test round? From the case head to the bullet tip? What if your test round is a short or long one? You don't want to base your measurement on that, do you?

and what is the 'prefered' depth? should there not be any marks on the bullet?

wouldn't calipers work for measuring?

You need to find that through experimentation. First, find out where the bullet hits the lands, then test a few different lengths to see what works best. I have rifles that shoot best when the bullet is into the lands when the bolt is closed, and others that shoot best with a lot of freebore. It depends on the rifle.


The real measurement that you want to take is from the case head to the place on the bullet where it hit the lands, right? For that, you need a bullet comparator.

 

[Slowdive]

I use a similar method. But in addition to the "slots" on the neck, I also milled off the rim and drilled out the primer pocket. I load the bullet into the modified case, and close the bolt. Then I open the bolt and push the "cartridge" from the muzzle end by pushing gently on the bullet out of the rifling w/ a cleaning rod.

You need to mill the rim off to prevent the extractor from pulling the case from the chamber. It'll ruin your measurement. You need to drill the primer pocket because you'll have to poke the bullet to get it out (neither a collet nor a kinetic bullet puller will work without a rim,). I also use the Hornady LnL bullet comparator set because the tips are not all the same. I do this a couple of times, if I get measurements within 0.001", I know I haven't muffed it up.

 

[timbo]

Poke it out, insert it back into the case and, what? The whole idea behind the Hornady (it used to be the Stoney Point) gage is to slide the rod up, lock it in place, poke the bullet out of the rifling, stuff it back into the gage/modified case so that the bullet bottoms out on the rod, and measure it with a bullet comparator (Google Hornady Bullet Comparator).

Oh, OK, now I see what you're saying. That makes sense. I may spring for the OAL gauge that Hornady makes then, unless you have a better suggestion...or try to make my own. I have access to all kinds of metal stock and a machine shop where I work. I'll also do some research on bullet comparators. Thanks for your help!

When I say 'bullet tips' I mean literally, the tips of the bullets. If you measure OAL from the case head to the tip of the bullet, what if the tip is slightly deformed? Let's say that you have a box of 100 bullets, and the tips vary by 0.005". How are you going to measure the OAL of your test round? From the case head to the bullet tip? What if your test round is a short or long one? You don't want to base your measurement on that, do you?

How does one get around variances between bullets in the same box? Measure/weigh each one individually? I guess I still have lots to learn.

 

[EddieCoyle]

Oh, OK, now I see what you're saying. That makes sense. I may spring for the OAL gauge that Hornady makes then, unless you have a better suggestion...or try to make my own. I have access to all kinds of metal stock and a machine shop where I work. I'll also do some research on bullet comparators. Thanks for your help!

I use the Hornady gage but there's no reason you couldn't make your own. The nice thing about the Hornady gage is that you can get modified cases that screw into the bottom that have the right headspace and a loose-fitting neck. You could make those too, but they're pretty cheap from Hornady.

How does one get around variances between bullets in the same box? Measure/weigh each one individually? I guess I still have lots to learn.

Don't worry about it. If you buy good bullets, the variation will be minimal.