OAL, Ogive, Comparator

[jwrowland77]

Ok I'm a newbie (reloading for only 5 months, only around 1k rounds under my belt) but I think I'm turning the corner.

I started this thread to see if I was on the right course or not.

When seating a bullet at a given OAL, it could seat deeper or shallower depending on if the bullet you used to set you OAL has the same ogive. If they don't, it could have a little longer or little shorter OAL.

The only way to be able to tell if it is the same distance from the lands, is to use a comparator, which measures from the ogive. I'm asking because I am trying to load more accurate ammo for my daughters .223 and for me 7mm RM and trying to make sure I have around a .02 jump.

I'm assuming that "match" bullets are more consistent in the making process, making the bullets in that lot almost identical (ogive, length, weight), which equals consistency when trying to shoot a match.

Am I on the right track of thought or not?

[1stmar]

You are on the right track, two tools that work well for this rcbs precision mic and hornady comparator. The hornady comparator is less expensive and it my opinion quicker to use and just as accurate.

[jwrowland77]

Originally Posted by 1stmar

You are on the right track, two tools that work well for this rcbs precision mic and hornady comparator.

I actually have both of those on my wish list at Cabelas. Hopefully my folks will pick up one or the other for Christmas or my birthday coming up soon.

[HJ857]

I like the Hornady better as well.

http://www.midwayusa.com/product/231...with-6-inserts

Match bullets really need to be measured as well, at least until they prove to be consistent. I've run across a lot of SMKs that I thought were disappointingly inconsistent.

You are correct that jump from the ogive to rifling is the more important measurement. Absolute (base to tip) OAL is important if you must stay within the length of a magazine.

[Unclenick]

Jwrowland77,

Just to be sure you understand, you don't need both tools. Just one or the other. The Hornady is more flexible because it adapts to other calibers. You can get inserts both for bullets and for case headspace datum measuring for it. You do need to own a caliper, though, where the RCBS product does the measuring for you. I just don't like the way the RCBS product uses a single ogive shaped gauge to find the throat.

If you want to find the throat with your actual bullet shape, the Hornady Overall Gauge, plus adapter case for your chambering plus their LNL bullet comparator with insert for your caliber plus the case headspace insert for your cartridge are needed. The inserts fit the same caliper adapter head, so you only need one of those. Use the gauge to find the bullet ogive, swap in the case headspace insert and find the shoulder. This is relative, so zeroing isn't required. Just find the difference in the two measurements and be sure to seat your bullets to obtain that same difference. The absolute numbers may not be the same. It's the difference that matters, as it reflects the distance from the shoulder, which the case headspaces on, and the bullet ogive location.

I know this seems like making you use two measurements instead of just one for seating depth, but it compensates for any differences there may be in the lengths of your cases and the gauge's adapter case. You only need to do it when you set up your seater die, so it doesn't actually eat up much time.

[jwrowland77]

Ah ok. I have calipers and Hornady OAL gauge and modified cases already. Looks like I'll just need to get the comparator and headspace gauge from Hornady and I should be set.

[Nathan]

You need an OAL gage, bullet comparitor and you might want to buy the headspace bushing while you are at it. I use the Hornady setup. I find it the best for my uses.

[hooligan1]

I use the Hornady Bullet Comparator and the Modified cases, it's easy and very accurate. I also use a Frankford arsenal digital caliper, which makes reading measurements faster,( I believe)along with trhe Comparator.

Also jwrowland, what is the reason for .02 jump? I mean how did you come to this conclusion, or is it even a conclusion or just a starting point? Myself, I try .003-.005 at a time, in increments, testing three rounds until I find "The One" and I have several different ones that I came up with while trying various different bullets, and bullet weights in my 7mm Rem Mag.... just saying...

[jwrowland77]

Well the .02 jump I came up with from reading the instructions that came with the OAL gauge. The instructions said from .01-.03 jump, so I figured I'd start in the middle until I get more comfortable with loading then gradually get closer to find that sweet spot.

Just mainly trying to be as safe as possible. With my daughters ammo I have been loading to 2.232 (.223). When I used the OAL gauge, touching the lands was 2.285. As you can see I was way off. I figure I can at least start at 2.265 as a good starting point.

[1stmar]

Unless you are using a competition seating die I get variances of .002, I don't think it makes sense to vary seating depth by anything less then .007-.01.

[jwrowland77]

What's the difference between competition seating dies and regular?

[Unclenick]

Dan Hackett, writing in the Precision Shooting Reloading Guide tells how he was loading Nosler BT's for his 220 Swift one day, but had 20 rounds loaded before he noticed that in switching from another bullet he'd accidentally turned the micrometer adjustment on his seating die the wrong way. As a result, these 20 rounds wound up seated too deeply, so the bullets chambered 0.050" off the lands instead of 0.020" off the lands as he'd intended and always used before. He considered pulling the bullets, but decided just to go ahead and fire these rounds in practice, and not to expect too much from them. To his astonishment, his rifle, which had never previously grouped 5 shots into under 3/8" at 100 yards, turned in two 1/4" groups and two bugholes in the low 1's with those loads. So much for the "best" distance off the lands being some universal number.

A lot of people may have used those kinds of jumps successfully, but a lot have fooled themselves into never finding their best jump because of believing in them too much. Berger has found their VLD shapes often want to be out as much as 0.150 off the lands to do their best, but it depends on the chamber. With some chambers they actually do best seated 0.010" into the lands (firm contact). You can read their recommended procedure for finding a best seating depth, here.

[jwrowland77]

Interesting. I appreciate that link. Since I'm a hunter I will be trying that second set of 24.

[1stmar]

I believe in experimenting in different distances, I too have had loads where they performed excellent .150 off the lands, hence the reason I use increments of .01 or more when working up loads. .003 could give you 50 different loads to try... No thanks.

Competition seating die has a micrometer adjustment on top and presumably tighter tolerances so variation of seating depth is limited and adjustments are easy to make. Excellent dies, pretty expensive by comparison. I don't have any but were I to get one it would likely be a redding.

[Unclenick]

The difference in the seating dies varies with the manufacturer. IME, the best one is the Redding Competition Seating Die. It uses the sliding sleeve that the Forster types do, but adds in a floating seater stem that self-centers. It also has a micrometer adjustment for seating depth. Basically, it helps bullets seat more coaxially with the case so they enter the bore better aligned. My first one was in .30-06, and it reduced runout by about a factor of 4 over my standard die, from about 0.004" bullet tip tilt to about 0.001" in the worst rounds.

Ironically, in very tight guns this can make less difference than in looser chambers. Harold Vaughn showed it made not quite 0.2 moa of radial difference to have a bullet seated tipped 0.004" the fired in a very tight benchrest type machine rest gun. But A. A. Abattiello showed long before then that it made about four times that much difference in a bolt match rifle (like a match Springfield '03), turning 1/2 moa groups into 2 moa groups. So it can be worth eliminating all the runout you can.

If you get a runout gauge, though, you can load with a standard die, then have a bullet size hole in your workbench and just learn to bend the cartridges lightly based on the readings, until they read straight.

[1stmar]

The hornady concentriciry gauge will "fix" the concentricity, but I always felt the way it worked it would alter neck tension so I am reluctant to use it. I will say, since I have gone to lee collet die (not to high jack the thread) and some changes in my seating procedures, the vast majority of my cartridges have runout of .001, some at .002 very few at .003 and virtually none greater then that.

[jwrowland77]

Sweet. Actually I am learning a lot by this little discussion. I always figure, you won't learn unless you ask.

This will definitely have me looking at my procedures and ways I can better it. I have only reloaded for approx 5 months an only around 1k rounds so far. Up until now, my main concern was just being as safe as possible to not make mine or my daughters guns go boom, especially with her behind the trigger.

Although a lot of my focus will still be on being safe, I feel like its time I can start fine tuning my loading of rifle ammo, and try and make it the best I can at this point in my reloading experience.

[TheTinMan]

Generally I really like the Hornady gauges. However, the Sinclair (Brownell's) "bump gauge inserts" fit the Hornady gauge and are made of steel instead of softer aluminum. In addition, the Sinclair inserts have an angled contact area with the case shoulder instead of a sharp edge. This matches the shoulder the case will hit inside your rifle's chamber.

2 cents +/-

[hooligan1]

I don't use a Competition die 1stmar, however it makes all the sense to me varying my increments minutely, two reasons for this: 1. I never miss the "sweet spot". 2. I get to shoot more handloads in this process!

[1stmar]

Agreed hooligan, it all depends on what you like more the hunt or the kill. I like the hunt to a point, not to the point where I have not achieved my goal (read satisfied) and I have shot out my barrel in the process.. Besides too many rifles and calibers to get to to look at .001 increments.

[Unclenick]

More importantly, a lot match bullets have as much as 0.010" length variance. Pretty much no point in being tighter than that if the bullets won't all end up with the same COL. Even ogive to case shoulder will vary plus or minus half that in some instances, and that's with a competition seater in play. Apparently spring-back from forming the jacket cups isn't 100% uniform; at least not where the seater ram touches the ogive.

The Berger method uses 0.030" (target) to 0.040" steps (hunting). I currently use the 0.030" approach to narrow the possibilities, then go ±.015" from the best 0.030" increment and don't go further unless I see a real difference. Usually I can just call it a day at that point. I use 5 shot minimums for this, round robin, so I shoot 20, then 10 more looking for refinement.

Note that a lot of folks find a couple of sweet spots at different seating depths. It's not uncommon, in addition to being close to the lands, for another sweet spot to show up at about 1 caliber into the case neck or with the full bullet bearing surface in the case neck, whichever is shorter.

[hooligan1]

Unclenick that info rolls of your tongue like an avalanche coming down a mountain.
1stmar, .003-.005 not .001. I specifically load and practice for "the kill".
Most hunter's don't require the accuracy and shooting skill that I require me and my family to have, some hunters only have one "super duper" hunting load for their main hunting rifle, I also have some that Only have one decent handload for them at this time only because I'm busy working on other peoples rifles as well as my kids rifles. Having said that I have one rifle that shoots several handloads of different bullet weights and powder charges as well as oal specs,( because I spent alot of time developing those loads).
It's pretty simple for me, to sum it up like this " Aim Small Miss Small", I never ever got to liking Missing.

[jwrowland77]

I never miss...and I never track...one welled placed shot right below the deer's jaw and bam...venison for the table.

[hooligan1]

And one "head bob" like deer are prone to and a wounded deer.

Probably not a good idea to start the ole "head-shot" thread here.
I never take one unless deer are at my feet and won't die.

[jwrowland77]

Probably right. I never take an unethical shot though.