Author Topic: How to make a homemade reamer for lengthening chamber neck?? (Read 1800 times)

bufflernickl · « **on:** July 17, 2004, 02:47:05 PM »

I've set the bbl back in my 6.5 Swede (exchanged one military bbl for another and had to close the headspace) and now the case neck is being forced into the leade.

My only neck/throat reamer is a benchrest reamer and is way under the size of the military neck. I've made a number of reamers for reaming holes, but never one to cut a square face (I need to lengthen the neck bore by .013"). I'd like to make a Q&D single-flute cutter on a bit of drill rod turned to a tight slip-fit into the .305" diameter neck bore. BTW, I don't want to wait for a special reamer to be made or to get a rental chamber reamer that would do the trick. Well, there's another consideration.. this mil chamber body is dang close to being to "benchrest specs" (.480" at the mouth) and a rental reamer would surely open it up, which I don't want (sure do wish the neck were similarly tight :-)

My first thought is this: drill out the leading end of the drill rod to give a wall of .020", which is wider than the neck cut and will provide plenty of chip clearance for the little bit I'm going to cut. I'd then grind around that rim, leaving a little teat about .015" high. After flame hardening and tempering, that nib would then be hand shaped into a cutting edge with a die grinder and a fine cutoff wheel. If cut with very little face angle, the flute ought to allow turning it in by hand with a center in the tailstock to keep it aligned. An indicator on the back of the drill rod will get my depth of cut.

I'd make a reamer from a twist drill exc. US drill sizes go from .302" to .312". Plus, I don't think a twist drill would make a very good face cut, even if the relief were altered to a bare minimum. The job could be done with a boring bar, but there are lots more ways to ruin the chamber with a boring bar than there are with a reamer :-)

Any better ideas? Maybe I've re-invented the wheel and made it square :-)

TIA/buffler

John Traveler · « **Reply #1 on:** July 17, 2004, 07:27:52 PM »

Buflernickle,

I've made throat reamers by starting with a standard straight shank machine reamer (available in standard size increments of 0.001" and center grinding a pilot end on the lathe.

You will need a tool post grinder to do this accurately. You don't even need to draw the temper. Just grind away, and get that square front shoulder you want. You then get in there with a fine hand stone or Dremel tool point grinder to your front cutting lips.

This is likely more accurate that trying to bore out the chamber throat with a homemade boring tool.

gunnut69 · « **Reply #2 on:** July 17, 2004, 09:20:43 PM »

bufflernickl-If I understand right you swapped a new military barrel onto your swede and the necks too short. What about the headspace. Most of the military replacement barrels are short chambered requiring a Chamber reamer and headspace guages to set the headspace after the barrel is installed. I'd wonder whats goin' on if the neck were too short but the headspace is OK,.. Building a half shell neck reamer shouldn't be too difficult, but I still wonder about the headspace..

bufflernickl · « **Reply #3 on:** July 18, 2004, 01:37:37 AM »

GN,

HS is short also, but not as short as the neck. I'll be "chasing headspace" as I lengthen the neck; that is, facing off the bbl flange (and breech face as necessary). When I get HS correct, I'll bore the neck "that much" deeper, as I'll be keeping track with an indicator.

We're talking only a few thousandths to get HS correct, so cartridge base extension past the breech is no more affected than it would be by positive HS (I set 'em up with just a tiny bit of crush on the unfired cases I plan to use).

This work is being done with the assistance of a fellow who builds 1000 yd target rifles, so I've a good check on safety issues.

Finally, I'm thinking about just rechambering this one. I have a reamer for 6.5-06 AI, and that round works easily through the Mauser military actions. It's a rechambering that has been done by the thousands. I don't need the extra ballsitic performance of the round, but it would completely clean up the body, neck, and throat (6.5-284 doesn't get these last tow). There is an issue with keeping the concentricity of the base at fireforming, as the 06 base is nominally .006" smaller than is the Swede base. However, I know a procedure to get the cases fireformed concentrically. Once that is done, they will stay that way.

The -06 conversion can make an accurate rifle even w/o concern with base concentricity, as proven by a bunch of Swede varmint rifles from back in the 60s. In mid-TN where I grew up fellows were shooting 400 yd+ groundhogs, using converted Swedes with no thought at all about that blown-out base. Couldn't have affected accuracy too much :-) One friend shot a gh at a measured 608 yds. one day, and returned the next day and shot another off the same rock just to show it wasn't a fluke!!!

BTW, appreciate and respect your concern about safety issues; it comes through in many of your posts to these boards. I'm still mentally composing an answer to one of your replies on another thread.. still have one bit of data to come up with; you're going to be surprised :-)

Cheers/buffler

bufflernickl · « **Reply #4 on:** July 19, 2004, 01:54:31 PM »

I simply rechambered the rifle... to 6.5-280Rem 40* Imp. (to get the longer than -06 cases)

I now have a tight chamber (forward of the oversize bit) a tight neck and a target throat.

The Swede case is nominally .006" larger than the "-06" but unfired cases are acutally ~018" smaller than the breech mouth measurement. I plan to bond a circular shim at the breech mouth to take up the slack so that case expansion is concentric. After frir-forming, I'll have a sort of rebated base case but it will work fine with no more fiddling.

Cheers/buffler

gunnut69 · « **Reply #5 on:** July 19, 2004, 09:23:54 PM »

I am confused. You can't lengthen the headspace measurement by facing off the barrel shoulder or the breach face! That will make the headspace in the rifle tighter. Remember the headspace is measured from the face of the closed/locked bolt and the datum line on the shoulder of the case. Removing (facing off) metal from the barrel face/shoulder will decrease that length...tight chambers need that distance to get longer, not shorter. If that barrel was origanlly a 6.5x55 the length of the neck and it's relationship to the shoulder would have been set by the chamber reamer. Now if I understand you you're proposing to 'bond' a ring of metal into the chamber?? to keep the rounds centered while they are fireformed. and the cases are going to swell by .018 inches... that is an awful lot.. I hope you were planning on using reduced loads to fireform.. even then your taking an awful chance of having a case rupture.

bufflernickl · « **Reply #6 on:** July 19, 2004, 11:58:41 PM »

Well, GN,

all that HS discussion is moot now, as I've rechambered. I've got -.003 HS, or a bit of "crush", plus .008" of excess neck length over a maximum-length case. Neck diameter is .292, requiring a bit of neck turning before fireforming, and another turning after.

As for the bonded ring, that comes out after fireforming as the swelled cases will then be concentric. Yeah, that's a lot of expansion, but cases will stand it quite well. It's a one-time thing and causes no reduction of case life. However, it takes a stiff load to get them fitting the chamber, like 51gr RL22 behind a 140 gr bullet. This is an "arm's length" operation, so in the unlikely event of a rupture, the firearm is well away from the face. I'll post a pic of the fireformed case if I can figure out how to do it.

Cheers/buffler

gunnut69 · « **Reply #7 on:** July 20, 2004, 08:03:25 AM »

Sir the discussion of your trying to adjust headspace is not moot. You don't measure headspace at .003, .003 of what.. Headspace in a rifle is a range. Not a distinct measurement. .008 Excess neck length?? The shape of the chamber is determined by the reamer, nothing else. It is possible to bore a chamber with a lathe but this requires a thorough understanding of headspace and machine tool operation and you did note you were using a reamer.. Then you have what's called a 'arms length operation'. I suppose that is your way of saying I may have created a problem and don't want it to hurt me.. That I would agree with. I would urge anyone reading this to be very cautious. Many of the things being done are questionsable at best and most likely down right dangerous.,

bufflernickl · « **Reply #8 on:** July 20, 2004, 12:59:37 PM »

SIGH!!!

Were you standing at the lathe?

Headspace most ceertainly *is* a dimension. It is the clearance (+) between the bolt face and the cartridge base when a round is chambered. Now, it may vary between different cases, but each specific case has a specific dimension. OTOH, I set them up for crush (- HS) to obviate that variation... and to get greater accuracy, just as the BR, 1000 yd shooters, etc. do.

Did you see how many reamers I used? Did you note that I put the body in with a .22 Cheetah reamer and the throat with a BR neck/throater?

So, as I said, the HS is .003" crush (with my cases) and I ran the neck .008" deeper than my longest case. Now all will be trimmed back to a common dimension which will give .013" from case neck to the end of hte neck bore.

There are mnore ways to skin a cat than one, and more ways to make a safe rifle than one. My cat is still hirsute, but my rifle's safe!!!

Let's see, my first chambering job... 1963.

Cheers/buffler

gunnut69 · « **Reply #9 on:** July 20, 2004, 09:33:54 PM »

Hey bufflernick;-} headspace is not the measurement from the 'bolt face to the casehead'! It is the range of measurements from the bolt face to the shoulder of the case on a rimless case such as the 30-06. On a rimmed case it is measured from the bolt face to the chamber surface that retains the rim(either a recess or the rear of the barrel). These ranges constitute the allowable headspace for a cartridge. You cannot have .003 clearance because the headspace on a 30-06 case in considerably longer than that. There is a minimum headpsace measurement but since you don't know what headspace really is that would be a meaningless number to you. No sir I wasn't at the lathe and I honestly have my doubts that you were. How can you possibly set the headspace on any rifle without knowing at least the correct definition or where the measurement is to be taken. You say your cases were a crush fit but where were these cases from? Were they fireformed in a chamber? to assert they are a crush fit you have to know the measurement of the headspace in the rifle the cases were fireformed in. Plus the use of a case to guage a rifles headspace is dangerous. Brass casings can be altered by the camming force of the action. Sir you are scary. I don't know you of course so only have what you have written in these threads to go by but you don't seem to have the knowledge needed to build safe rifles. Your proposed methodology is full of dangerous assumptions and laden with a tremendous burden of ignorance. Perhaps it's just your failing to communicate what it is you are actually doing but the lack of understanding of even the simple concept of headspace leaves me with grave doubts concerning you abilities. Your cats hair situation, of course, not withstanding.

bufflernickl · « **Reply #10 on:** July 20, 2004, 11:40:35 PM »

GN,

The term headspace is troublesome when talking about a rimless cart. It was coined in the days of a rimmed cartridge, and it applied precisely. After the rimmed cazrtridge came into common use, the same term was applied to a vastly different type of measurement, where it makes little sense.

I'll agree with you that the "allowable headspace" is a range. Also that technically the headspace on a rimless cartridge is measured from the shoulder. However, if you insert a GO gage in a chamber, you find the actual headspace by measuring the clearance between the back of the gage and the bolt face.If it's day, .002", you say it's good. If it's .010" you say it's bad (except in the case of an SMLE, which seems to thrive on any amount of slop :-) There is no way to actually measure the true headspace unless you section the chamber, at which point the measurement is moot.... well, I supose you could have a series of gages varying in lenght by increments of .0001" and keep going up until you felt bolt drag, but that's impractical as well.

So, we all talk about "headspace" as the clearance between the bolt fgace and base of the case.. AND.. we all know what is meant, the practical measurement, even though the term wea are using is technically wrong.

As far as setting up a chamber to slightly crush the cartridge cases that you plan to use, it is recommended by no less a light than POA, esp when setting up a chamber for an improved cartridge. Can't find any guilt about the way I did mine. AND, my partner uses this method and the same reamers that I used, to build competitive 1000 yd rifles. Not one has exhibited any dangerous tendencies, but lots of them have won trophies :-)

I snapped at you on that last post because you seem to jump in where you don't fully understand what's going on or what's been done and then you cast aspersions on the person or the method. I'd just as soon drop this one before it becomes a p*ssing match, which isn't good for the forum or for us. Deal?

Cheers/buffler

gunnut69 · « **Reply #11 on:** July 21, 2004, 07:13:24 PM »

BN-
Some on this sight may not be quite so 'into' the slang so I would prefer we use proper terminology and be very clear about what we say we are doing. I surely don't wish any kind of match and headspace is a subject with many views... In any case have a great day..

bufflernickl · « **Reply #12 on:** July 22, 2004, 12:40:27 AM »

Yeah, GN,

time si better sepnt working on guns or shooting them :-)

The 6.5 is coming along nicely. Got a sack of .280 brass yesterday and if I can make a 6.5mm mandrel for the neck turner today, I'm ready to fireform cases.

Bought an 8mm Rurkish Mauser yesterday that is just perfect for $99 complete, incl tax. This thing has a Turkish walnut stock that would make a custom rifle proud. Dark purple streaks running longitudinally with vertical tigertail throughout the whole stock!!! I think it was likely a Turkish armory restock and it appears to have an armory reblue as well. It's great that we can get such high-quality firearms so cheaply.

Even the postwar Eastern Eu Mausers, M48, appear to be a good deal if someone is interesting in sporterizing with a new barrel; $79 for a good, if rough, 98 Mauser action!!!

With the demise of Bishop and the near-production stoppage of Fajen, reworking these military actions isn't as common as it once was, but it still offers good fun at a reasohnable price for those so inclined. We have a .243 on such an action (chambered and throated without proper understanding of headspace :-) that regularly (not *every* group) shoots 1/2" groups at 200 yds!!!!!! Of course, the bbl never saw the inside of a Mauserverke, but still the entire rifle (less optics) cost less than $300.

Have fun.

Cheers/buffler

gunnut69 · « **Reply #13 on:** July 22, 2004, 04:05:37 AM »

Bishop and Fajen are both extinct. Fajen bought bishop many years ago and Midway (Larry Potterfield) bought Fajen and then thru a few mistakes bankrupted them. There are many fine companies still amking pre turned stocks. RichardsMicrofit, GreatAmericanGunstock, ElkRidge(@ReamerRental), and not least, Wenigs. Fred is at Lincoln Missouri and most of the Fajen/Bishop workers and machines are working in his shop. A good place to do business with good people. As for the 243, luck is always better than skill. The difference between safe and not, is small indeed.....

bufflernickl · « **Reply #14 on:** July 22, 2004, 05:01:04 AM »

GN,

I'm trying to get along with you, but you are making it difficult. Your comment about luck vs skill is extremely insulting and I must believe that you meant it so. I maintain that your comprehension must be faulty.

How many rifles have you built that can match this performance? How many that will shoot under 1" at 200 yds??? How many under 10" at 1000 yds? Maybe you've even built couple that approach 8"

I asked you kindly to drop the insinuations; I have to say that I'll not reply to another such post.

Best/buffler

gunnut69 · « **Reply #15 on:** July 22, 2004, 09:09:57 AM »

I was simply replying in the same vein to your comment about the 243 'chambered and throated without proper understanding of headspace'. I meant no insult. Although I tend, from what you've written to believe that your understanding may well be less than you'd like us to believe.