Is there an accurate way to determine COAL for each specific, individual rifle?

Bobby B.

You may want to re-word your question. If you have a magazine rifle, your magazine box length will be one limit, the freebore of the barrel will be another limit and the type of bullet you use will be another limit.

Bobby,

I purchased one of these, but you'll also need to purchase the modified case for the calibers you have, unless you make your own. Hornady OAL Gage

You can also purchase a set of something like this, that will allow you to measure from the Ogive on the bullet, which is much more accurate than measuring from the bullet tip. Comparator You can buy the inserts in a set or you can purchase them separately.

The best way for me is a bullet comparitor. stony point has a pretty good one and you can make your own.

Hey Bobby, you need what we affectionately around here call a "thingy".

graybird and hivelosity mentioned one marketed by Hornady, called the OAL Gauge



to which you will need a modified case.

There is a learning curve when using one which some around here seem incapable of completing but is commonly used with excellent results.

Use your Cleaning Rod and a Jag Tip with the end flattened. No need to waste $$$HUGE$$$ on any kind of non-repeatable reading Thingy.

Thanks guys for the info. I've been using the cleaning rod method for years but want to switch to something more positive.

Bobby B.

quote:

Originally posted by Bobby B.:
I've been using the cleaning rod method for years but want to switch to something more positive. ...

Hey Bobby, If you do find something that is better than the Cleaning Rod Method, I'd also like to hear about it. At least if you waste $$$money$$$ on a Thingy, you will get to experience first-hand the non-repeatable measurements. Gives you a good excuse to dip into the Sour Mash.

By the way, you may be interested in converting OCL to ODL. It sure makes Testing various Seating Depths much easier.

Best of luck to you.

quote:

Originally posted by Bobby B.:
Thanks guys for the info. I've been using the cleaning rod method for years but want to switch to something more positive.

Bobby B.

I don't blame you for wanting to measure with a little more precision than is typical when measureing to the 1/1000ths of an inch between the edges of 2 pieces of tape or 2 marks on a rod or tape. That is "close enough for government work" and close enough for some (I'm not mentioning any names HC ).

Like I said the Hornady has a learning curve but will give you accurate measuring with patience and application. However, you need to allow for the headspace on the modified case which is the difference in the case-head-to-shoulder measurement between your fired cases and the modified case.

The method I use is a tool from R-P Products called the C.O.L. E-Z Check which cost me $25.00 four years ago. His number is 318-424-7867 and his e-mail r_reeves61@bellsouth.net . This is a side business from his oil field work but he will get back to you eventually.

It works like the cleaning rod method but with several significant improvements. It is shown here with the Hornady


but with 2 easily lockable collets


and a brass tip


that is removable for the smaller calibers


and has the significant advantage of measuring between 2 hard surfaces


which makes if fool proof (which helps me out and anyone else using it, I'm not mentioning any names HC ).

Now the Hornady makes an excellent tool for inserting the bullet to the lands but you could do it with a dowel or pencil like with the baling wire and duct tape crowd does (I'm not mentioning any names HC ).

BTW HC, you got any TOMATOES
like this?

For bolt actions, just color the ogive with a felt tip. Repeatedly chamber the cartridge and adjust the length until you don't see any rifling engagement marks.

No offence but I gave up the 'felt pen colored ogive' and 'soot covered ogive' method years ago in favor of the 'cleaning rod' method. I now want something better.

Bobby B.

quote:

Originally posted by woods:
BTW HC, you got any TOMATOES
like this? ...

Ahhhh - " NO!!!" Not yet anyhow. One of the neighbors has " 1 " which is nearly ready to pick. His son "cheated" and gave him two early BIG plants which were in bloom when they went in the ground.

Did you get those at the Farmers Market???

I find the "bullet tip to base of case" measurement unreliable for lead tipped bullets simply because the amount of lead exposed and the integrity / condition of the lead tip is variable. The Barnes TSX gives uniform reading but the lead tipped & even the Nosler BT do vary.

The felt tip method is still valid for knowing how far off the lands you are seating your bullets in THAT PARTICULAR RIFLE . All my hunting ammo is now at least 0.020" off the lands as I do not want any bullets getting jammed in the lands when reloading in the field.

I have just bought a Hornady "head to shoulder" measuring tool. It has certainly helped me get precise partial full sizing of my cases to a consistent and repeatable level.

What I have now done is stuck a 5mm fibre washer on one of the spare bushes that I do not need and use that to measure the seating depth to "ogive". This is not the exact length but a very important reference measurement which can be repeated. Each bullet brand & weight will have a different reference measurement. But all of them will be 0.020" off the lands.

I've been struggling with this one too. I've had no problems using the RCBS Precision Micrometer for two 338 WMs but it didn't work well with my new 30-06.

So, I bought and tried the Hornady tool in the 30-06. Not much better so I improvised.

I took the hard projectile from the RCBS Precision Micrometer and inserted it in the Hornady tool case and got pretty consistent measurements.

I noticed Sinclair sold a tool similar to the one mentioned by Woods and I had already ordered it before seeing this thread so we'll see how it works out once it arrives.

quote:

Originally posted by Bobby B.:
No offence but I gave up the 'felt pen colored ogive' and 'soot covered ogive' method years ago in favor of the 'cleaning rod' method. I now want something better.

Bobby B.

Hey man no problem. It's simple, fast and cheap. Just sayin`.

I have a Stoney Point (now Hornady) tool too but sometimes I just don't want to screw with it. Especially on rifles with a gentle lead. It isn't so bad on chambers with a 3 degree lead, but with a 1.5 degree it can be a pain in the ass.

quote:

Is there an accurate way to determine COAL for each specific, individual rifle?

Yes. First, use the "thingy" or method of your choice to find the approximate seating length to rifleing contact. It need not be precise, close is plenty good enough.

Seat your first bullets about 20-30 thou off that point and try a series of varying charges with the powder and bullet of your choice.

After you find the best shooting charge, load another batch with bullets starting maybe 10 thou off the lands and move back in 5 or 10 thou steps until you find the best shooting OAL. That's it.

Few factory sporter rifles shoot their best touching or even close to the lands so learning that is interesting but knowing PRECISLY where bullet to rifleing contact occurs really isn't even helpful. You are only going to use that point as a seating starting reference for the following experiments anyway.

Most common rifles seem to do their best shooting various bullets from .025" to as much as .100" off the lands, sometimes even more!