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Using the Hornady Comparator and OAL gauge to adjust bullet depth


Attention Reloaders! Are your groups too big? Have you tried just about every powder on
the market and can’t seem to get those little holes to stick closer together? Well today is your lucky day because I am
going to show you how to improve your accuracy! Using my sophisticated drawing of a rifle’s
chamber, let me show you what we’re trying to do here. When you chamber a round into your rifle,
the bullet when fired, will need to travel a few thousandths of an inch before contacting
the rifling. The part of the bullet that first touches
the rifling is the ogive right here. You can achieve consistent accuracy, as a
general rule, by reducing the distance that the ogive has to travel or jump before it
contacts the rifling. Before we can do this, we will need to measure
the maximum overall length of your specific rifle using a few tools that should run you
about $100 or less (hopefully less). Please see the description box for links to
these items. You will need an overall length gauge, a modified
cartridge case for your caliber (mine is 308 Winchester), a bullet comparator (which is
what you will use to measure the bullet at the ogive not the tip) and a measurement caliper. By the way, I have no affiliation with Hornady,
much like I have no affiliation with Victoria’s Secret, I just umm, admire their products. *ahem* Nevermind. All right, let’s start off with a safety check. Once the rifle is cleared, we can start assembling
our tools. First, grab your overall length gauge and
loosen the screw that secures the bullet retention rod so that it can slide freely. Then take your modified case and thread it
onto the gauge. Finally, take the projectile that you want
to measure and slide it into the modified case past the ogive, basically so that only
the tapered end, the top half is visible. Next, tighten the retention rod screw to lock
the position of the bullet. Now, take this Frankenstein of a creation
and chamber it into your rifle. Look through the ejection port to ensure that
the case is seated all the way into the chamber. Next, carefully loosen the retention screw
then ever so gently push the rod in slowly. This in turn will push the bullet until it
contacts the rifle lands. You want to push or tap gently then stop immediately
when you feel resistance. You do not want to push the bullet further
into the rifling, you just want it to kiss it gently on the cheek (so to speak). Carefully lock the retention screw then pull
out the gauge. Here’s a Bro tip, sometimes the bullet sticks
to the rifle lands and won’t come out. Some folks recommend that you can push it
out with a wooden dowel inserted into the barrel, however I have a better idea. Keep a firm grip on the gauge, then lift up
your rifle. Next, very gently wiggle it side to side and
let gravity drop everything down. And there you have it, the maximum cartridge
overall length for your rifle. Also, if you have a semi-automatic rifle,
Hornady makes a curved version of the gauge that is inserted through the ejection port. Quick side note – on some rifles, your overall
length will be so long that the bullet sticks out too far from the case neck. Unfortunately, for safety, I recommend that
you do not proceed with these steps. You can still mess with bullet seating, but
it will require a different procedure that I can cover in another video. Ok, now we need to actually measure the length. We start off by attaching the bullet comparator
to your caliper. Loosen the screw then slide the notch onto
the blade of your caliper. Tighten it down to secure it. Now slide the lower caliper blade so that
it contacts the comparator and then zero out your measurement. To measure your cartridge, insert the projectile
end into the comparator, then make sure the bottom caliper is sitting flat inside the
notched end of the gauge and everything is secure . Here’s my measurement, two and two
hundred forty two thousandths of an inch. 2.242 is where the bullet touches the rifling,
so let’s back it down, and a good place to start is in increments of twenty thousands
of an inch or .020. So, 2.242 minus .020 is 2.222. Let’s go to our reloading bench and load our
first set of rounds. Keep adjusting your bullet seater until you
reach your measurement and here we go, 2.222…and a half. Ah, good enough for me. Trying to measure half of a thousandths of
an inch would drive me nuts anyway. Load about 10 of these rounds then hit the
range. If they do not group to your expectations,
subtract another twenty thousandths of an inch and try again. If you intend to load your rounds into a magazine,
you may need to keep shortening your overall cartridge length until it fits. I had to do this for my Remington 783. This process will need to be repeated for
every projectile of a different weight that you intend to shoot. For example, I shoot 150, 168 and 178 grain
bullets, and each one required their own measurements. I would also recommend measuring similar grain
bullets from different manufacturers. Why do all this ogive measurement stuff instead
of the bullet tip? Because the length from the ogive to the bullet
tip can vary wildly. Here’s an example. Let’s measure several commercial cartridges. Here’s a random fact of the day, according
to the BBC, a bear can eat for 20 hours in a row. It must have enough fat reserves to survive
the winter, so it does this by eating for 20 hours in a row, sleeping for four, and
then going at it again. Which I would say is a skill easily matched
by your average teenager. As you can see the numbers are all over the
place and it’s not uncommon for a number of cartridges to all have similar (or close to
similar) ogive measurements but different lengths when using the bullet tip. All right, that about does it. Guys, I hope you find this video useful. This is an immense topic and potentially dangerous
if not done correctly. I tried to cover as much as I could, however,
if you have any questions, please post it in the comment section and I’ll get back to
you right away. Unless of course I’m occupied with Hornady
products or ummm…a Victoria’s Secret catalog, in which case it might be a while. Thanks for watching and take care!

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