Reaming Necks vs Neck Turning for Milsurp Chambers?

[Joshua]

This is a new question about reaming cases vs neck turning, I promise!

From what I have read neck turning will always be the more accurate option. But will I notice the accuracy difference in my situation?

My special circumstances:
• 7.7x58mm formed from 30-06
• necks are running .014” to .015”
• I’m running bullets sized .318”
• I’d like my to necks at .312”
• I suspect I have doughnuts, I don’t own a tubing mic, so I’m measuring with calipers (poor method)
• I currently own two L.E. Wilson trimmers
• I can pick up a L.E. Wilson caliber specific reamer for $30.00
• a neck turning set up will be significantly more expensive
• Milsurp chambers on both of my rifles are predictably sloppy and loose
• Triggers are stiff on one, and extra stiff on the other.

So my question is this. With the sloppy inaccurate nature of these rifles chambers will I be able to notice any accuracy difference between reamed v.s turned necks.

I know that a few of you have done extensive testing in this area. I’d be interested in your input.

 

[RicinYakima]

Having shot CBA Military benchrest matches for about 25 years now, the answer is no. FWIW

 

[CZ93X62]

I have Forster reamers in a couple rifle calibers--22 and 30. 22-250 can thicken necks with several firings, so I check that after a couple firings. Federal brass was prone to that, W-W not so much so far. Hornady acts and weighs like W-W, though mine only has 2 firings. I am more concerned about bullet clearance during the firing sequence than with concentricity per se--my sporter grade rifles in the context of my skill level likely can't discern any possible differences between neck-turned vs. reamed necks.

The most use I've had for the 30 caliber neck reamer came in pistol ammo--7.62 x 25 Tokarev, to be specific. The Broomhandle Mauser and the CZ-52 pose no dimensional poetry or anomalies, but the Chi-Com Type 54 (TT-30/33 variant) definitely did and does.

The milsurp ChiCom ammo that was sold with these pistols had bullets that mic'ed .307" and secured with a stab crimp. The chamber necks were quite snug, and the throat and groove diameters in the barrel were .310"+. This was 1991-2, and no reloadable brass in 30 Mauser or 7.62 x 25 existed (other than Fiocchi) existed in the know world back then. I reformed and cut off W-W 9mm Win Mag brass to make my brass (500 pieces, what a marathon project THAT was....) and it worked well--in the Broomer and the CZ-52. I ended up firing all of the rounds in the Broomer and the CZ, and setting aside 200 fired casings for the Tokarev alone. These got resized FIRST, and THEN reamed to enable acceptance of .311" bullets and clear release upon firing--not to mention reliable feeding. Most reaming instructions call for the operation to be done prior to resizing, on fired brass.

 

[Joshua]

These got resized FIRST, and THEN reamed to enable acceptance of .311" bullets and clear release upon firing--not to mention reliable feeding. Most reaming instructions call for the operation to be done prior to resizing, on fired brass.

I will try reaming both fired and resized brass to see what gives me the desired wall thickness. The reamer that is available is designed for .303 British. My fired cases may be a little to large for that reamer to do much good. I may need to make a special deep expander similar to the ones Ian makes. I would then resize, expand, and then ream the brass.

 

[Ian]

The only way to accurately ream necks to a desired thickness is to run them into a form/trim die and ream by hand from the top.

 

[fiver]

neck turning is also dependent on the interference fit of the spud that goes inside the neck.
you can try to sloppy it around, and it can be too tight,,, neither one is really useful.

 

[Ian]

The reamer head sold for trim machines is really only for reaming out the "dreaded donut", not for enlarging the whole inside diameter. The brass will stretch flat between the flutes and not really get cut. The case neck acts as a pilot for the reamer so it can cut the donut part at the base of the neck in a fashion concentric with the rest of the neck. The donut can't expand much because the geometry of the neck/shoulder junction, so it gets effectively cut out

 

[462]

. . . the answer is no.

. . . neither one is really useful.

So settles the many years of agonizing.

 

[popper]

So you get a donut from pushing the spud through the neck. Where do you think that metal comes from? When pushing, the spud moves brass to the shoulder area, pulling should leave it there and not create a donut! When you fire, that moves the excess into the neck, makes the donut. Reaming would remove the donut on a fired case. It will weaken the shoulder/neck area. Reaming or neck turning is to 'uniform' neck thickness, something reaming doesn't really do correctly. Reamer may be less $ but neck turner lets YOU set neck thickness.

 

[Ian]

I think he meant neither too loose nor too tight on the turning spud is useful. Both techniques (three, actually) all have their place.

It bears mentioning again what Ric was alluding to...you won't tell the difference in accuracy (if that's the only reason you're messing with necks) unless you're already shooting itty-bitty groups. Getting extra-thick necks, uniformed and sanded to a taper which exactly matches your chamber neck with loaded clearance measurements having three zeros to the right of the decimal, most certainly will decrease cast bullet groups provided that your chamber is reamed dead-nuts on center with the bore.

 

[fiver]

provided that your chamber is reamed dead-nuts on center with the bore

sooo not cut by dead eye pete on a pipe machine then?





AKA the Remington factory.

 

[Joshua]

I need to remove metal to get my loaded round that .002” of neck chamber clearance. I don’t want to hurt my accuracy. But at the end of the day decreasing wall thickness by two or three thousandths is my main goal.

So now that we agree that my sloppy chamber isn’t gonna notice the difference in methods. Maybe I should have asked this question? What is the most effective expedient, and economical way to decrease neck wall thickness?

 

[RicinYakima]

FWIW, in my experience, and only mine, the centering of the case and bullet is better done with the case body and chamber and head of the case and the bolt face. MilSup chambers are made to function with the poorest quality ammo the country had to provide. Other than snipers, accuracy of 6 inches at 200 meters will work for us troops.

Match shooting for recreation is fun and the "art" of making these old guns shoot better than they were made for is a challenge. But you are not going to make a match rifle out of it anyway.

 

[Ian]

What is the most effective expedient, and economical way to decrease neck wall thickness?

For you, turn a stepped plug to fit your MT3 headstock spindle taper, turn the end down to about 3/8" so it makes a positive stop at about the middle of your three-jaw chuck jaws. Turn about an inch of the end of a 3-4" 3/8" or so tool steel to the ID of your resized case necks minus .005" and harden just the turned part, then draw to a dark straw. Hold the big end in your tailstock drill chuck. Stick case in jaws with the head against the stop you made, slide your tailstock over until the mandrel is through the neck, lock it to the ways, snug the scroll chuck, and turn off the desired amount and length of necknwith a sharp, HSS form tool. Grind the tool tip to have the correct SAAMI radius at the neck/shoulder junction and improvise a carriage stop for easy repeatability. Sharpie mark your cross-slide dial for consistent thickness.

 

[BudHyett]

Thoughts:

1. Reamers follow the existing hole, a reamer will not even the case neck dimension.
2. Outside neck turning is the easiest way to get even case neck walls. This can be very simple or very involved as you desire.
3. Both approaches are only useful for tight neck or fitted neck cases.
4. Military chambers are too loose to work with either approach.

Using a bushing neck sizing die, I set aside 100 cases per rifle to outside neck turn to .015 for the bushing die. As Ric says. "Match shooting for recreation is fun and the "art" of making these old guns shoot better than they were made for is a challenge. But you are not going to make a match rifle out of it anyway."

 

[Joshua]

For you, turn a stepped plug to fit your MT3 headstock spindle taper, turn the end down to about 3/8" so it makes a positive stop at about the middle of your three-jaw chuck jaws. Turn about an inch of the end of a 3-4" 3/8" or so tool steel to the ID of your resized case necks minus .005" and harden just the turned part, then draw to a dark straw. Hold the big end in your tailstock drill chuck. Stick case in jaws with the head against the stop you made, slide your tailstock over until the mandrel is through the neck, lock it to the ways, snug the scroll chuck, and turn off the desired amount and length of necknwith a sharp, HSS form tool. Grind the tool tip to have the correct SAAMI radius at the neck/shoulder junction and improvise a carriage stop for easy repeatability. Sharpie mark your cross-slide dial for consistent thickness.

Yes. You are right. I hadn’t worked out all the details in my head, but I knew that doing it on the lathe was actually a third option. It is also most likely the most accurate option.

This would need to be a winter post hunting season project.

Also, buying tooling for the lathe is a much better use of funds, then buying either reamers of neck turning tooling.

 

[Joshua]

Military chambers are too loose to work with either approach.

Bud, it is only necessary because these two barrels slug at .316 and .3165”. I’m using bullets that are sized at .318”. The brass is cut down thicker walled military 30-06. And, the chamber is designed for a .312 jacketed projectile. That’s why this Military Chamber is “Tight” at the neck and loose everywhere else.

 

[fiver]

this should cut your groups in half.

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[CZ93X62]

Hmmm. Those yellow metal bits that appear after the reamer enters the case neck and gets hand-cranked are coming from SOMEPLACE. I'm not trying to change anyone's mind here, just describing what I did and why I did it--safe bullet release.

 

[RBHarter]

I'll let you know if a really big groove has any hope at all with formed brass from 270 .
It has a felt lump on the lower neck of COW fire formed cases but doesn't seem to be felt seating sized cases . So fat is this one I'm actually considering just seeking out a loose 8×57 sizer and swapping in a 30 cal decapping pin/expander . I used to have an 8mm expander ball but all 4 in the box o parts are .307 & .310 now .

My throat is .3195 , with a .318 (as it stands now it may change with some paper patch down the bore ) groove . I don't know if the lands are sufficient to cut the paper or not , it seems to be working in the 6.5 .

I don't have a correct sizer for the bullet dia yet as I don't want to be guessing at the best guess anymore . I did find the 323-175R2 mould and it looks like a .320 sizer might get it done .

I reamed a few 22-250 made from 308 many years ago and saw no difference between that and factory brass but the rifle was a good one to begin with . I've not turned any necks with proper tools but I have relieved some fat necks where reamers and probably even pilots weren't available . (Let's call it getting every cycle available from an 06' and leave there.)

Reaming formed cases with the shoulders pushed up into the neck hasn't shown to be a detriment but I'll know better soon .