Brass length and free bore

[ArtinNC]

Something to think about when ordering a chamber . I ordered a 222Rem match reamer had all the dementions on the print but forgot the over all case length . It was to have zero Free bore the other day I checked the chamber and my reamer cut the chamber .035 longer than the brass that is 1.698 Lapua . So it realy has a .037 gap from brass neck to the rifling , so is that about like .037 free bore ?

 

[RGRobinett]

Something to think about when ordering a chamber . I ordered a 222Rem match reamer had all the dementions on the print but forgot the over all case length . It was to have zero Free bore the other day I checked the chamber and my reamer cut the chamber .035 longer than the brass that is 1.698 Lapua . So it realy has a .037 gap from brass neck to the rifling , so is that about like .037 free bore ?

Roger THAT, except that it is neck diameter as opposed to 0.0005" to 0.0010" over the bullet diameter - not a particularly desirable attribute . . . but may not be a wreck . . . case:chamber OAL is an often overlooked attribute. RG

P.S. This is more of an issue when short-for-caliber bullets are in play, or, where one maximizes the free-bore
length, moving longer bullets away from the shoulder/neck junction, to favor case capacity, over case-neck:bullet shank interface. When one is expecting, say .125-.150" of neck:shank engagement, giving up 0.035" to 0.040" of that "grip" may be difficult to swallow.

This is a not uncommon issue with 30BR reamers, some of which not only cut excessively LONG necks, but also have "real" free-bore . . . which is a wreck. Prior to ordering a reamer, it's wise to have brass, "in hand" - wish I'd have known that from the beginning. Following some tutelage fro [the late] Stan Ware, I began ordering reamers with zero, or very little free-bore, then establishing free-bore via a separate reamer, which has delivered excellent results.

 

[ArtinNC]

I have only shot 100 rounds so far and it looks promising . so it may be ok , but I'm not happy with the reamer .

 

[JerkyFreak]

Couldn't you have stopped cutting the chamber 0.035" earlier?

What is the reamer neck length from the neck-shoulder transition to the start of the neck-freebore transition? Is the extra length from the shoulder dimension or the neck length dimension?

 

[Will Henry]

Stop cutting early and the headspace is too short. ...035 longer than the brass is excessive. I don't know what specs are for the brass and chamber without going to look. IIRC, the nominal clearance is .005 with a tolerance of +.010 for the reamer. The minimum for the brass is .005 under nominal, I think. Like I said, I would have to look it up. WH

 

[ArtinNC]

The extra length is on the neck length dimension , so you can't stop it short .

 

[ArtinNC]

If I stoped it short then the headshace would be short , My brass is 1.698 lapua , norma and Star Line all the same . I would have to send the reamer back and have the neck shortened . But the barrel is all ready chambered . I'll just see how it is going to shoot .

 

[Roeder]

Stop cutting early and the headspace is too short. ...035 longer than the brass is excessive. I don't know what specs are for the brass and chamber without going to look. IIRC, the nominal clearance is .005 with a tolerance of +.010 for the reamer. The minimum for the brass is .005 under nominal, I think. Like I said, I would have to look it up. WH

If the reamer chamber length is established based on the length of 6mm BR brass it will be short. The brass tends to shorten when it is necked up.

 

[Steve Kostanich]

Art,
Send the reamer back to the maker and have the neck shortened up your spec and the throat section relocated to your spec, then rechamber.
I had to do his with my 30 BR reamer that had a neck way too long. It now has .005+/- clearance between the case neck end and the chamber end.
FWIW
Steve Kostanich

 

[Will Henry]

I think the OP was speaking of a 222 reamer, not a 30 BR. Nonetheless, that is a valid point. The same is true of the PPC. If the 222 rifle does not perform well. I would be inclined to form brass from 223 to gain some length. WH

 

[jackieschmidt]

If I stoped it short then the headshace would be short , My brass is 1.698 lapua , norma and Star Line all the same . I would have to send the reamer back and have the neck shortened . But the barrel is all ready chambered . I'll just see how it is going to shoot .

the most important thing is where the bullet winds up in the neck after you ascertain your ideal seating depth.

Freebore and chamber length are two separate terms. Freebore begins where the neck ends.
True, if the chamber neck that the reamer cuts is a little long, then the bullet will stick Further out.

I have ran into a rather unique problem with shooters who want to use my reamer print. I have to warn them that if they use that reamer, they will have to make their brass the same way I do. That being, blowing it out rather than necking it up. Blowing the case out results in the case retaking much of it’s original 1.560 length, hence my reamer is designed to take advantage of this.

My chamber is 1.550 over all length. My trim to length is 1.540.

 

[ArtinNC]

Guess I'm going to make 222 brass from 223 brass to make the brass .038 longer so I'll not have trouble with the carbon ring from short brass . Cheepest way to go .

 

[243winxb]

https://saami.org/saami-glossary/

FREE BORE​

A portion of the chamber, usually cylindrical, forward of the casemouth of a diameter larger than the projectile in which rifling is not present. See Bullet Jump. See Throat.



Related Terms: BULLET JUMP, THROAT

 

[AlNyhus]

Guess I'm going to make 222 brass from 223 brass to make the brass .038 longer so I'll not have trouble with the carbon ring from short brass . Cheepest way to go .

Good plan. -Al

 

[ArtinNC]

Yeah , I have tuns of 222 Lapua , Norma brass now I have to find 223 brass , seems everyone is out of it of course . Good thing I have another 222 .

 

[ArtinNC]

Just for trial I just took 2 - 223 Win brass and formed to 222 to have brass .030 longer so my carbon ring will be snaller . Then I had to turn the necks next to the shoulder to have the necks the same thickness the hole length . I got one .0108 and .0114 and the other .0110 and ,0112 . I don't think I can do any better than this . My chamber is .250 , so what is your thoughts ?