Measure freebore, will this work?

[Riesel]

Using a Hornady OAL device and a marked up with sharpie bullet. Measure the bullet ogive with the proper insert. If it doesn't make a ring on the bullet, then mark a spot with an exacto knife or some other sharp device. Bullet is now marked where the ogive begins. Insert bullet into over all length bullet case and adjust depth with adjustment rod. Measure from base of case to case mouth (ogive).
Make a note of this. insert tool with cartridge case and bullet and adjust just as if you are looking for distance to lands or COL. which you are. Remove and measure. If I subtract the smaller number, the bullet inserted just to the ogive mark (or the cartridge length) from the larger bullet to the lands number will this give me a faily close number for freebore?

Thanks

 

[Dusty Stevens]

Does an arbitrary measurement really matter? Forget the hornady tools and use a case from your rifle to find the lands and go from there. The actual measurement matters none

 

[JFrank]

Do you have the Reamer print?

 

[IdahoSharpshooter]

back in the old days, we used to just seat a flat base bullet backwards (long) in the case and chamber it.

 

[Riesel]

No reamer print. An arbitrary measurement would be helpful.....Does this barrel have a .090 freebore or a .170 freebore? I'm more interested in finding out if this will work to find the freebore. Not sure what loading a bullet in ass backwards might tell you but I would like to know how you can measure freebore using that method.

 

[Dusty Stevens]

No reamer print. An arbitrary measurement would be helpful.....Does this barrel have a .090 freebore or a .170 freebore? I'm more interested in finding out if this will work to find the freebore. Not sure what loading a bullet in ass backwards might tell you but I would like to know how you can measure freebore using that method.

Somebody used to sell a steel plug to do this. A flat base bullet will push back into the case and leave it exactly at the point youre wanting to measure

 

[shoot4fun]

Somebody used to sell a steel plug to do this. A flat base bullet will push back into the case and leave it exactly at the point youre wanting to measure

Sinclair

Have we gone overboard on freebore?

 

[Dusty Stevens]

Sinclair

Have we gone overboard on freebore?

Yes sir. Its the next ss pin.

 

[shoot4fun]

Yes sir. Its the next ss pin.

Oh, and those Sinclair steel plugs are for measuring chamber length and not distance to the lands.

 

[Dusty Stevens]

Oh, and those Sinclair steel plugs are for measuring chamber length and not distance to the lands.

There you go. Shows how much i know about gimmicks

 

[Dos XX]

I can't really follow what you are doing. My reading comprehension skills may be the culprit. However, I don't think you can measure it the way I think you are describing. You don't know how much chamber length is in front of the end of your case before you get to the "throat".

Since you stated your choices are either .090 or .170, I am going to guess that it is a .308, as those are common .308 reamers.

Load a Berger 200 Hybrid in a case and seat it to touch. It doesn't matter if you use the Hornady modified case or one of your own. If the boattail of the 200 hybrid is above the neck shoulder, it is .170. If it is below, it is a .090.

If you don't know for sure that it is either .090 or .170, you have a more a difficult problem and a chamber cast is the likely solution.

Tell us a little more about what you are trying to do, and we might be able to advise, or at least wander into an off topic discussion.

 

[JFrank]

All a person really needs to know is CBTO Datum as Dusty has pointed out it is an arbitrary number

 

[Dos XX]

He may be trying to determine if he can shoot a certain bullet in the rifle without having that actual bullet and not having a reamer print, bought a used rifle maybe.

More info and I bet we can get to the bottom of it.

 

[IdahoSharpshooter]

riesel,

simple. IIRC, it will tell you the leade point of origin. Chamber case length is cut when the barrel is chambered. It leaves a 90-degree step at the front. There may or may not be any freebore before the leade begins. It is usually 1/2-3/4 degree per side. Think forward end of freebore transitioning into the actual throat.

 

[Riesel]

I can't really follow what you are doing. My reading comprehension skills may be the culprit. However, I don't think you can measure it the way I think you are describing. You don't know how much chamber length is in front of the end of your case before you get to the "throat".

Since you stated your choices are either .090 or .170, I am going to guess that it is a .308, as those are common .308 reamers.

Load a Berger 200 Hybrid in a case and seat it to touch. It doesn't matter if you use the Hornady modified case or one of your own. If the boattail of the 200 hybrid is above the neck shoulder, it is .170. If it is below, it is a .090.

If you don't know for sure that it is either .090 or .170, you have a more a difficult problem and a chamber cast is the likely solution.

Tell us a little more about what you are trying to do, and we might be able to advise, or at least wander into an off topic discussion.

Impressed with your Detective skills. Yes, these are .308. The .090 freebore I chambered on a 10 twist barrel with the idea of shooting 200 grain or so bullets. Shooting 168 grain bullets very well but I can see that the 200 grain will invade into the powder room. Bought a 11.5 twist Tactical off this forum and lo and behold when I put the 168 in to measure to the lands the bullet is barely in the case. Using a 200 grain bullet it is as you described with the boattail right at the neck shoulder junction.
Thanks for your information, but, I'm still wondering if I can measure freebore using the method as I described.
That's the real question.
Thanks to all for your interest.

 

[243winxb]

I'm still wondering if I can measure freebore using the method as I described.

No, if i understand you correctly. The chamber ends about .010" longer then case maximum trim length. Chamber 2.025" + .015" Tol. for a 308 Win. (SAAMI)

Need 2 sized scrap brass. Make a sized case with extra trim length.
Cut neck off 1 case. Put square cut piece against case mouth. Seat flat base bullet nose first. This holds the cut neck. Bullet base must be deeper then cut off neck. Square case mouth. Chamber gently.

Will bolt close, no. Trim case a little at a time,till bolt closes. This is chamber length.

Subtract chamber length from longest head to ogive measurement. Should be close to throat length.

More confused? I guess.

 

[Riesel]

243winxb, I see were you are going with this and that would solve the problem. I'm just trying to determine the FB on any barrel. You buy a new chambered barrel (or gently used for that matter) and they state that the FB is such and such. You start working up loads based on that info and something just isn't jiving. You want to double check the FB and are looking for a method to do so. Since I'm pretty much looking for approximate number, I might be able to use the cartridge length base on a SAMMI print as the reference. Total length of cartridge to bullet ogive minus SAMMI cartridge length equals FB. Hmmm. I'm not in the shop to test this. What say you?

 

[Dusty Stevens]

243winxb, I see were you are going with this and that would solve the problem. I'm just trying to determine the FB on any barrel. You buy a new chambered barrel (or gently used for that matter) and they state that the FB is such and such. You start working up loads based on that info and something just isn't jiving. You want to double check the FB and are looking for a method to do so. Since I'm pretty much looking for approximate number, I might be able to use the cartridge length base on a SAMMI print as the reference. Total length of cartridge to bullet ogive minus SAMMI cartridge length equals FB. Hmmm. I'm not in the shop to test this. What say you?

Most saami chambers have a freebore already but i guess you could get that from a print

 

[Riesel]

Yes, we're attempting to do this on a barrel that didn't come with his pedigree papers

 

[Monte F]

My Brittany didn't come with papers either, still a good dog. Hopefully you have a good barrel there and not the runt.