seating depth question: land marks on Berger 73's?

[mjgillen]

Hello all,

Fairly new to all this, but trying to learn. I am trying to figure out my seating depth using the method described in Mike Ratigan's book. He says to take a shell with the bullet sticking out enough so that it will hit the lands when the bolt closes and then measure COAL. Do this a few times until you get a consistent reading. This is the "jam" length. Next , find the "zero" where the bullet is just NOT touching the lands by backing out until you DON'T see any land marks on the bullet. Makes sense to me. However, when I look at the bullet, it seemed to ALWAYS have some land marks so I picked out a fresh bullet and discovered that the whole box has what looks like tiny land marks (or marks running lengthwise down the nose of the bullet about 1/4 way down). So my question is:

Is this normal? If yes, then how am I supposed to tell a land mark from these other marks? Is not normal, um what should I do?

My rifle is a Savage 12FV .223 bullets are Berger 73gr

Thanks,
Michael

 

[3081FTR]

Don't bother with land marks. Follow this method. http://forum.accurateshooter.com/threads/finding-your-lands-video.3892411/page-5#post-36769933
Best and most reliable method I have come across.

 

[mjgillen]

Thanks 308 I'll take a look...

 

[3081FTR]

There are a million ways to do this stuff. Since you are new have a read of Erik Cortinas 100 yrd load dev process as well. You don't have to be really experienced to get a handle on it and same with Alex wheelers seating depth approach its some what black and white which makes it real easy as a starting point.

 

[mjgillen]

Thank you for the link to the Wheeler videos. However, I'm not so certain my factory Savage 12FV will have such delicate "feel" on the bolt per the video. Also I'll have to take my bolt apart to remove the firing pin and ejector which I know I'll need to learn at some point but drinking from the firehouse is not what I had in mind as an answer to my question. But I'll learn.

I'll read through that thread...

Michael

 

[3081FTR]

you'll be surprised once the bits are removed just how loose it is. If you blank a primer it pays to know how to remove the FP
Over to you if that's a lot or just doing it once doing it right

Good luck.

 

[DHuffman]

Don't be intimidated by a savage bolt. They're very simple and the only "special" tool I've need for disassembly is a punch small enough to drive out the ejector retainer pin.

 

[mjgillen]

Ok I'll give it a go...

 

[jray57]

Buff the bullet with steel wool prior to closing the bolt-easy to see the impressions from the lands. And yes learn how to remove firing pin and ejector and hook the cartridge rim under the extractor before closing bolt

 

[mikecr]

Not sure why sneaking up on JAM would be useful. Knowing touching land relationship can be somewhat useful for description sake. Ultimately, all that matters is the CBTO that testing shows as best.

The easiest method I've used to determine touching COAL is the old cleaning rod method. WOODS describes a version merchandised by R-P Tool here: http://www.reloadersnest.com/forum/topic.asp?TOPIC_ID=9027
Special about it I guess is the precision stops and blunt tip. This measures muzzle to bolt face(stop#1) and muzzle to land touching bullet tip(stop#2). The difference is touching COAL for THAT bullet. Then you build a reference dummy cartridge with THAT bullet seated to produce touching COAL. Then you measure & log your CBTO off this dummy round & throw it in a drawer.

But then, you'll never need this information (not really). Eventually you'll likely do Berger's recommended full seating testing, determining best CBTO with that bullet choice, log it, set your dies, and never change this for the life of that barrel.

 

[Shynloco]

r

Hello all,

Fairly new to all this, but trying to learn. I am trying to figure out my seating depth using the method described in Mike Ratigan's book. He says to take a shell with the bullet sticking out enough so that it will hit the lands when the bolt closes and then measure COAL. Do this a few times until you get a consistent reading. This is the "jam" length. Next , find the "zero" where the bullet is just NOT touching the lands by backing out until you DON'T see any land marks on the bullet. Makes sense to me. However, when I look at the bullet, it seemed to ALWAYS have some land marks so I picked out a fresh bullet and discovered that the whole box has what looks like tiny land marks (or marks running lengthwise down the nose of the bullet about 1/4 way down). So my question is:

Is this normal? If yes, then how am I supposed to tell a land mark from these other marks? Is not normal, um what should I do?

My rifle is a Savage 12FV .223 bullets are Berger 73gr

Thanks,
Michael

Michael,
I have been using Mike Ratigan's method of finding jam/touching the lands, for years and it works fine in several calibers. Mike R certainly has the credentials for helping others learn this fun sport and his methods are time tested and target accuracy tested, so they work. What you need to do is to use 0000 steel wool to clean off the markings each time you close the bolt and locate the markings. Once the markings disappear, you now know the bullet isn't touching the rifling anymore. You also need to measure the ojive of each bullet after the cartridge has been closed into the chamber and the bullet seated in the process. Also hand load the cartridge into the chamber each time carefully and don't load them from the magazine if you have one. Write down the Ojive measurement each time. I only use one bullet and remove the marking(s) with the steel wool. Once I find the "sweet spot" of touching, I back out another .010-.020 and start my testing from there as the touching or jam will increase your pressure which is not what you want for starters. PM me if you need more help or are confused.

Alex