Most accurate OAL method

[gunrack]

I have tried two methods for measuring the OAL. The cleaning rod down the muzzle to the bolt face and then placing a bullet just touching the lands and measuring the difference. I also have tried using the Hornady tool with a comparator. Which method is more accurate or is it 6 one way or half dozen of the other?

Haven't had any problems either way just asking which one is the more accurate or preferred method of experienced re-loaders.

Thanks

 

[chkunz]

Make ten measurement both ways and look at the variability in the measurements. The dirty little secrete here is that the methods that we have to make this measurement are not as accurate as most people think. Once you understand the limitations of the measurement process you can make an informed decision as how to use the data.

 

[MarkS]

I have tried two methods for measuring the OAL. The cleaning rod down the muzzle to the bolt face and then placing a bullet just touching the lands and measuring the difference. I also have tried using the Hornady tool with a comparator. Which method is more accurate or is it 6 one way or half dozen of the other?

Haven't had any problems either way just asking which one is the more accurate or preferred method of experienced re-loaders.

Thanks

I use the Hornady tool to get close. Then I set the bullet out in a case. Buff the bullet with steel wool, so you can see rifling mark. Chamber the round, adjust until you see square rifling marks on the bullet. This is close to 0.020" into the lands. Then you can go from there. I like to be into or out of the lands, just touching can cause problems ( some will touch, others may not. With a little throat wear and you are not touch any more ). I start most for my load testing at 15 to 20 into the lands. This is the only true way to know where you are with the lands.

Mark Schronce

 

[Paddyd]

Since very few bullets are equal when measuring from the tip I say you gotta use a comparator to measure from the Ogive which is the bearing surface that will first come into contact with the bore. The tips of bullet measuring is basically worthless.

 

[M-61]

Since very few bullets are equal when measuring from the tip I say you gotta use a comparator to measure from the Ogive which is the bearing surface that will first come into contact with the bore. The tips of bullet measuring is basically worthless.

Yes. And taking the same box of bullets and measuring base to ogive is somewhat surprising by itself. The only reason to measure to the tip to get an COAL would be for use in a magazine fed rifle.

 

[Kodiak99317]

 

[M-61]

Make ten measurement both ways and look at the variability in the measurements. The dirty little secrete here is that the methods that we have to make this measurement are not as accurate as most people think. Once you understand the limitations of the measurement process you can make an informed decision as how to use the data.

That's for sure.

 

[gotcha]

measuring from tip of bullet is iffy at best. Hollow points tend to vary in length, as well as, other types. Measuring from the ogive ( your Hornady tool) is more reliable. Wether you look for a square mark made by the lands or one that is more rectangular is up to you. Some bbl.'s powder/bullet combinations have a relatively wide seating depth "window" others are less forgiving. Knowing EXACTLY where a bullet just touches isn't as important as being able to obtain a reliable COMPARATIVE measurement from the ogive then adjusting seating depth for best accuracy.

 

[Marksman63]

Best no brainer method

 

[Laurie]

I use the Hornady tool to get close. Then I set the bullet out in a case. Buff the bullet with steel wool, so you can see rifling mark. Chamber the round, adjust until you see square rifling marks on the bullet. This is close to 0.020" into the lands. Then you can go from there.
Mark Schronce

That's the method I've determined is best having tried most if not all tools and tricks over the years too. Another tip there is to field-strip the bolt beforehand removing the striker / mainspring etc assembly and check that the cases you're going to use chamber freely - the bolt handle should drop under its own weight. With the bullet seated long, you can feel reasonably well how much resistance there is in chambering an over-long inert round - the further the bullet is in the lands, the more effort needed. No apparent effort required doesn't mean the bullet is 'out' in itself as 'just kissing' will often produce this condition given the camming action in a bolt-action mechanism. So scrutinise the bullet under good light with a powerful magnifying glass. One can often see a just-touch situation as a thin broken line around the bullet ogive/shank junction area. Seat your bullet at whatever jump deeper needed or longer for however much you want to be 'in' plus or minus a couple of thou' if you've got this.

Also, there are usually some spurious marks further back on the bullet no matter how carefully the inert round is chambered / extracted. The trick is to look for near identical marks spaced evenly around the bullet circumference, and to ignore one-offs.

Keep the inert round as a 'pattern' to set up or reset the seater die (but simply screwing the seater stem down onto a correct-OAL round usually gives a setting around 5 thou' too long IME). Measure and retain the comparator reading, but if you also retain the inert 'pattern' rounds appropriately marked up, it's easy to use them as a check rather than looking up things in notebooks etc. If you have more than one comparator insert in a calibre, mark one up and always use it. I've found that two inserts sometimes give identical readings, but not always - I have one pair from the same manufacturer that give readings 10 thou' different. Of course, if you check and they DO give identical readings, no problem, no marking needed. (Keeping the inert pattern also means that if you lose your comparator insert in that calibre and have to buy a new one, there are no worries about consistency when working off a written down measurement.

I also do a COAL measurement and retain that, but only for QuickLOAD modelling.

 

[Sheldon N]

Use the method in the video above, and measure the distance to ogive, not the OAL.

I've also used the Hornady tool, but I think the video method is both more accurate and repeatable. You don't need any fancy tools to remove the firing pin and ejector from your bolt. Just use a loop of shoelace or paracord to pull back the firing pin spring while you unscrew it. Then use a 1/16" punch to remove the ejector retaining pin, taking care not to lose it since it's under spring tension.

An additional benefit is that you'll be able to get good feedback on how much you are sizing your case relative to your chamber when you full length size. A shoulder bump of .001 or 002 will likely leave a little bit of resistance to closing the bolt and you'll need to size it down a tiny bit more to get a case that chambers freely and lets you feel just the bullet into the lands.

 

[gunrack]

Make ten measurement both ways and look at the variability in the measurements. The dirty little secrete here is that the methods that we have to make this measurement are not as accurate as most people think. Once you understand the limitations of the measurement process you can make an informed decision as how to use the data.

The most repeatable by far for me was measuring from the chamber with a fire formed case using the bullet comparator. I took one of my fired cases, drilled it out and taped it with threads to match the Hornady tool and measured it 10 times. I was able to only see .002" range in variation between all of the measurements.

 

[gunrack]

I use the Hornady tool to get close. Then I set the bullet out in a case. Buff the bullet with steel wool, so you can see rifling mark. Chamber the round, adjust until you see square rifling marks on the bullet. This is close to 0.020" into the lands. Then you can go from there. I like to be into or out of the lands, just touching can cause problems ( some will touch, others may not. With a little throat wear and you are not touch any more ). I start most for my load testing at 15 to 20 into the lands. This is the only true way to know where you are with the lands.

Mark Schronce

I will definitely give that a shot. Thanks for the help!

 

[gunrack]

Best no brainer method

Thanks for posting this.

 

[MarkS]

I will definitely give that a shot. Thanks for the help!

I did my new Savage 6mm BR barrel last night. The video is how I do it, I just go to 0.020" into. The Hornady and Stony point will lie to you, I have been there and done that. I use the Stony Point as a starting point.

Mark Schronce

 

[chkunz]

The most repeatable by far for me was measuring from the chamber with a fire formed case using the bullet comparator. I took one of my fired cases, drilled it out and taped it with threads to match the Hornady tool and measured it 10 times. I was able to only see .002" range in variation between all of the measurements.

I think you are getting very good results, I do not get this good with the methods I have tried. The concepts seem ok but the tools are klunkey. Also I do not have a lot of confidence in this process so the fault may lie more with me than with the tools and methods.