OAL Gauge
- Thread starter KLS
- Start date
Fired formed case sized to chamber, or sized (with a Redding body die) on dropped stripped bolt, what ever you prefer. I use Red locktite with bullet. Can't get any better than that. I slightly size the neck with my Lee collet die, to get a better fit otherwise it's next to impossible to keep the bullet in place. Redding body die and Lee neck collet die is the best combination for me.
Last edited:
Take a fired piece of brass (fired in your rifle). Drill and tap it 5/16-36. A lathe or quality drill press makes it easier, but you can do this with a basic hand drill and a cheapo tap from Amazon. It isn't really a precision piece of gear, and making one with a simple drill won't make it any less useful or "good." The important part is that it's been fired in your rifle.
Hope that helps.
Hope that helps.
And how are you supposed to measure the datum to case head ? Measuring from the tip of the bullet isn't consistent, measuring from the datum that the bullet makes contact with the rifling, is the right way. And.. as the throat wears that measurement changes and needs to be remeasured.
223AI can be tricky to drill, but it can be done with proper set up. I've done many 222rem with no issues. If you bugger one up, just try again with another piece of fired brass. Brass fired in your rifle will give you a much more accurate reading.
Couple tips:
1) use a lathe if you have one available - this is ideal, but certainly not required
2) if you're using a drill press make clamp jaws cut to the general profile of the brass out of scrap wood. This doesn't need to be super accurate, just get close enough to support / center the brass and keep it perpendicular to the table. drill a hole about the same diameter as the case head through the wood piece, and then use your band saw to cut the wood in half across the center of that hole. Use these pieces in your drill press vise to hold the work.
3) use a FL die to support the brass. Just don't seat it in all the way - keep the die off the shoulder of the brass. the dimensions of the body aren't so important - you just want to make sure that you don't move the neck or shoulder at all. You'll need v-blocks (also easy to make out of wood) to hold the die in your drill press vise.
If none of this help you and you still don;t want to make the case yourself, I'd be happy to make one for you if you send me two pieces of fired brass and a CP extra small prepaid box for return shipping.
There's absolutely no need to measure the datum to the case head for bullet seating, but if you really want to do this, you just need a headspace gauge (made by every company that makes reloading tools) and a pair of calipers.
Bullet seating depth is relative to the case head, not the datum line on the shoulder.
The datum to case head will match your chamber (-.001") with a piece of fired brass. If the case fits your chamber perfectly, then you just use the bullet of your choice and push it forward until it touches the lands. lock that position with the set screw on the rod, pull it all out and measure the OAL using a bullet comparitor gauge (or similar). This will give you the distance from the case head to the bullet ogive rather than the tip.
Some people measure to the tip, but there will be 2 or 3 thou variation this way, even with the best bullets. Ogive is the number that matters here.
Hope this helps.
Fire formed case from your gun, put cotton balls in your case, enough to hold the bullet from falling inside. Take your unloaded rifle with barrel pointing up and use the locktite method. This will give the best and prevent actually engraving the bullet which gives false measurements. You want the bullet just touching the lands.
I use what is sometimes called the cleaning rod method, except I use drill rod and a couple drill bit stop collars, and dial calipers. It measures to the tip, but is still right for that bullet. You can always measure to the ogive afterwards.
LOL.
Measure the OAL of a handful of bullets out of the same box. They will all be different. Any measurement that involves the bullet tip will be worthless.
I’ll try that again for you. The measurement is right for “that bullet”. Not every bullet of that type, not every bullet in the box. It doesn’t have to be. Set your seating die with “that bullet”. You end up in the same place with a different method.
Sometimes there’s more than one way to de-fur a feline. For what its worth, I got my ogive measuring comparators 30 years ago.
Never got the use of a OAL gauge (modified case type) for finding max seating depth. Isn’t the measurement that you’re looking for from the bolt face to the lands? How do you get that with an open bolt and resting the case chamber on the shoulder? Isn’t the only accurate way to measure from the bolt face to where the bullet touches?
I know a lot of you have more experience precision handloading than I do. Help me understand.
I know a lot of you have more experience precision handloading than I do. Help me understand.
most of the mesuring tools are called comparators for a reason, they give a measurement to some point on the bullet ogive and does it consistently
it doesn't matter which spot is picked, as it is only compared to some other length, for comparison
ie, the Sinclair nut, sits down on the ogive somewhere. Make a round that fills the chamber to the lands, now that is the max for that bullet
when seating use hte same nut for measurment to a length shorter or the same as the dummy, in comparison
muddy, iknow
it doesn't matter which spot is picked, as it is only compared to some other length, for comparison
ie, the Sinclair nut, sits down on the ogive somewhere. Make a round that fills the chamber to the lands, now that is the max for that bullet
when seating use hte same nut for measurment to a length shorter or the same as the dummy, in comparison
muddy, iknow
You are kind of right but have missed that the headspace range is only 0.004". As long as the modified case is within the SAAMI spec, the seating depth will be no more than 0.004" away from the bolt face dimension.
As we would always want to seat at least 0.010" off the lands, that potential 0.004" error is not meaningful.
Most of the time, the modified case is not going to be at the minimum SAAMI headspace length and the chamber at the maximum headspace length so the actual gauge error from the assembled rifle dimension will be only a thou or two, which is more than close enough.
So .004” doesn’t matter, a thou or two one way or the other doesn’t matter? OK, lets go with that.
I’m sitting at my loading bench measuring bullets (because I have that kind of time, its cold out). Noslers are too boring, out of 20 there’s maybe 1 a thou over and 1 under the norm. Exposed lead tips aren’t as good, but most are right in there. Hollow point match bullets are the worst of course because they are.
So why are my thous horrifying and your thous don’t matter? Maybe neither one matters that much.
I’m sitting at my loading bench measuring bullets (because I have that kind of time, its cold out). Noslers are too boring, out of 20 there’s maybe 1 a thou over and 1 under the norm. Exposed lead tips aren’t as good, but most are right in there. Hollow point match bullets are the worst of course because they are.
So why are my thous horrifying and your thous don’t matter? Maybe neither one matters that much.
I broke one Hornady tool, bought another one, just more careful with it now. I measure a fired case vs the Hornady case and add the difference. Unless you want to shoot jammed stuff, the Hornady gauge give you a reference point, maybe it is .005 out , if you go back .020 thou and you are really at .015 or .025, the world won't come to an end over it, as you now know what length you started at on CBTO.
Yea that’s what I have been doing. I just take my ejector and firing pin/ spring out and seat that bullet until the bolt falls down. Clean up the bolt and oil the springs while I’m there.Or you can use a method that doesn’t have the error, and doesn’t require buying the tool and special order tap and making or buying the modified cases.
It’s also drop proof
I get that the 4 thou may not matter if you are starting around 20 thou off and seating deeper to tune a load if needed. Just have to live with the fact that you don’t really know how far away you are. Not sure if that matters.
I start at the lands whenever possible, call it lightly touching with no chance of debulleting a load. Far short of engraveing anyway.
Something that may be interesting can be demonstrated with the rod techinique since there is no case involved the bullet is just put in the barrel. Simply dropping the bullet in under its own weight will result in a jam of about 35 thou compared to easing it ahead feeling for the slightest resistance.You can push them in hard with the Stoney point/Hornady tool too. The dented neck method results in considerable jam, so when the old timers suggested using that method then backing off 30 they probably accidently were back at light contact and not jumping anything. Its not like we’re measuring to an anvil or brick wall or something else that has a definitive touch/no touch point.There’s a lot of room for interpetation and one guy’s jumping 20 is the next guy’s 10 jammed.
Either way it’s a starting point to experiment from, and they all work. It’s just their number, not a set in stone absolute. When people talk about varying their jump 3 thou at a time all I hear is they made the cartridge 3 thou shorter. They might not be jumping anything, just playing with lighter jams. Not that there’s anything wrong with that.
Something that may be interesting can be demonstrated with the rod techinique since there is no case involved the bullet is just put in the barrel. Simply dropping the bullet in under its own weight will result in a jam of about 35 thou compared to easing it ahead feeling for the slightest resistance.You can push them in hard with the Stoney point/Hornady tool too. The dented neck method results in considerable jam, so when the old timers suggested using that method then backing off 30 they probably accidently were back at light contact and not jumping anything. Its not like we’re measuring to an anvil or brick wall or something else that has a definitive touch/no touch point.There’s a lot of room for interpetation and one guy’s jumping 20 is the next guy’s 10 jammed.
Either way it’s a starting point to experiment from, and they all work. It’s just their number, not a set in stone absolute. When people talk about varying their jump 3 thou at a time all I hear is they made the cartridge 3 thou shorter. They might not be jumping anything, just playing with lighter jams. Not that there’s anything wrong with that.
