Precision Magazine, May 2010, page 57-59

Well, as this shows, the believers are gonna' believe "because the guy knows what he's doing" and "because he shoots good" with no concept of how it's good, and no ability to question why.

I'm an unbeliever.

Until someone explains how you can support a reamer to get it to cut a hole off center.... (the point here is to correct eccentric necks... it doesn't matter "how good the Lapua brass is.")

And until someone can explain to me how to set up and establish the outside diameter in relation to this reamer....

I'm an unbeliever.

I'm an unbeliever because I don't believe there's a gain to be had in smoothing up an off center hole in the interest of improving accuracy. Try this process with a long-range gun shooting VLD's...... :rolleyes:

Learn WHY necks get turned... it ain't to make them shiney and perty.....and it ain't to make then fit the gun.


As a backyard hack with a Harbor Freight lathe in his barn...... it is my opinion, from a machinists standpoint, that the purpose of a reamer is to clean up an established hole, PERIOD.....reamers are not designed to move holes over.

And if you DID support and preload one such that it actually corrected a hole two things are immediately apparent:
-#1, you're using the reamer as a single-point tool, not a reamer.
-#2, the hole would have to be well supported, not like a case neck.



AND........ the question must be asked,,,,,,,,corrected to WHAT???





Ohhh, and AJ300MAG, the writer of the article knows all this..... Page 58, second paragraph from the bottom the writer makes this statement.... "The reamer is held in in a full floating holder, allowing the reamer pilot to follow the inside diameter of the neck keeping the reamer from bell mouthing the neck of the case."

Just so's you understand..... "bell mouthing the case" means cutting a tapered hole.

UUhhmmmmm, it's cause by affixing the reamer, not allowing it to float. The process of correctly using a fixed reamer is too complicated to explain here, heavily dependent on preload and flex characteristics of both the tool and the workpiece.


It is my opinion and assessment that the method outlined in Precision Shooting offers NO advantage over shooting un-modified brass. There, is that clear enough?

The method outlined in PS of inside reaming the necks of PPC brass serves ONE purpose, it gives a person another way to make brass that will fit in a rifle with a "tight neck." I submit that while it's not a GOOD way, IF one has a tight neck and needs brass, it will make case that will fit in the rifle. It will fit and will safely shoot...... regarding "the elimination of donuts" it is no more effective than outside turning. If your hedspace is short and you grease your rounds, yer still gettin' a donut. If your resizer's set too low, yer still gettin' a donut.

I decline to comment on Dr Subramainian's letter re the granular crystalline structure of brass and the efficacy of cutting it in certain ways "for strength" but I disagree with the entire final or conclusion paragraph of he article......and the points contained therein, individually.




There..... that oughtta' be plain enough to polarize the believers and unbelievers. :D


al
 
As a backyard hack with a Harbor Freight lathe in his barn...... it is my opinion, from a machinists standpoint, that the purpose of a reamer is to clean up an established hole, PERIOD.....reamers are not designed to move holes over.

So, the primer flash hole reaming tool that I use TO MAKE THE FLASH HOLE CONCENTRIC WITH THE PRIMER POCKET on my Remington Ultramag brass doesn't work. It's an optical illusion that after reaming the holes they only APPEAR to be concentric with the primer pockets... :rolleyes:


alinwa said:
No one, no where, no how has ever recommended nor even tried reaming a 6MMBR barrel to .330 neck......
 
Consider Pushing a case into a sizing die similar to the Wilson Neck die with Bushings. Have the bushing be .2605 (OD of loaded round for .262 nk) Then while case is in the die ream the neck with a reamer the size of 6mm bullet at Pressure ring (.2436ish). This reamer has to be supported concentric to the center of the die, and the cartridge chamber has to be concentric to the center of the die, so that both the reamer and the case neck are in perfect alignment. The bushing would have to be tight in the die so that it doesn't float like it does in a wilson type die. The die bushing would keep the brass inplace forcing the reamer to cut the neck so that runout is removed and so are some of the neck thickness issues.

This being said, this practice has been tried before and was proven to be marginal at best. Neck turning showed better results.
 
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Your Close Paul, REALLY close

Make the chamber die one piece. The die should be .001" under the size of the fired brass, including the neck. I want the neck held in compression so it has no where to go. On the neck end, a hole bored and jig ground concentric with the die, 5/8" diameter and 3/8" deep. In this hole I'm going to put a carbide drill bushing that is a metal to metal fit to the die, the hole in the bushing is jig ground to .0002" clearance over the diameter of the reamer. The O.D. and I.D. of the bushing has zero runout.

Carbide bushing for lubricity and it's heat expansion propreties...


Cost effective, NO. Prove there's more than one way to skin a cat.:D
 
My .222 neck ream die is like a FL, in that the full case is supported, and there is considerable added height to the die that forms a concentric support for the neck reamer. I can assure you that this does not produce necks that are anywhere near as concentric as outside neck turning. Of course there is always the question of at what level does neck thickness variation become visible on the target? I don't know the answer to that one.
 
Boyd I used to check my loaded rounds for runout. Anything over .002" TIR to .003"TIR (worse case) would get marked on the bullet with a marker and placed in the right corner of my ammo box. I'd shoot that ammo for fouling shots. Thing is, at 100 yards that stuff shoots some dinky groups.
 
So, the primer flash hole reaming tool that I use TO MAKE THE FLASH HOLE CONCENTRIC WITH THE PRIMER POCKET on my Remington Ultramag brass doesn't work. It's an optical illusion that after reaming the holes they only APPEAR to be concentric with the primer pockets... :rolleyes:

Yup....

they are close, they are also single-flute reamed by a supported reamer if you're using the device for the purpose stated.




Originally Posted by alinwa
No one, no where, no how has ever recommended nor even tried reaming a 6MMBR barrel to .330 neck......

C'mon Al.... :) .... that's a low blow!

Of 5 billion humans present on the surface of the earth (and sometimes a few in orbit) ONE actually did try this...... AND gets it to work ...... (and quite WELL too, I might add ;) ) The fact that the guy lives in a machine shop and is capable of making anything from rotors to rocket motors helps. :D

Well, OK.... and maybe a couple others have done it too.... AND I MISSED IT!!! ...... I did apologized to all and sundry, admitted that I was WRONG, and glad to be wrong..... my reaction was to the fact that misapplied this is freakin' DAN'ROUS!! And the tolerances required to ensure the neck has room WHILE the bullet is still well started WHILE the caseneck flaps out the requisite mile-or-more before sealing.......And I'm still not really convinced that many folks have thought this through well enough to attempt it. Looong-seated bullet? Looong freebore to keep the bullet in line while the neck pops out?? This method ain't suitable for the average bear.



And, I was AGAIN wrong in my phraseology above in stating that a supported reamer is in essence "a single point tool..." It's NOT...

And your use of a die for support while inside neck turning is valid, and it DOES give one a way to establish a datum. This is one of the steps TJ Jackson employed back in the day. PITA to set up and use for multiple cases though! Reaming necks isn't completely useless anyroad.....even I've got a range of inside neck reamers and chucking reamers which I do sometimes use for inside neck reaming prior to turning.

None of this changes my stance re the ref'd article.

Also, on a side note, the authors use of a synthetic bullet was innovative I guess. 'Course if I had my own plant which could poop pa'roppriate plastic pellets it'd be piles more appealing, TO ME........


al

BTW, I'm not trying to be argumentative here, this is just how I talk. I'm PASSIONATE about this stuff! I'm more concerned with truth than with my personal convictions..... I love to be shown the error of my ways.
 
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