Neck-Sizing once-Fired .220 russian brass

S

stevenorlando

Guest
Hello All,

I fire-formed some .220 Russian brass in my 6ppc (neck dia 0.262). The fired brass measures 0.262". A loaded round measures 0.259", so I used a 0.257 bushing, and I can insert a bullet with my hands.

Is there too much "springback"? Do I need to use a smaller dia bushing in my S-Type Redding neck sizing die.

The first time, I obviously used a full-length sizing die and I didn't have that problem.

Steve
 
Something isn't right with your stated measurements. In my experience, fired cases from a .262 neck chamber will have around .001 spring back from the chamber dimension. I just pulled a freshly fire formed (.220 Russian to 6 PPC) case from group in a loading block and measured it with a 1" mic that reads to .0001. Dragging the neck through the mic, to be sure that I have the fit that I wanted, and did not oval the neck with the mic., the neck OD measured .2612. I have never measured a similar case neck that did not show spring back. Your measurements are only as good as the tools and techniques that you use. My first guess is that your necks are thinner than you think that they are. Are you using a good micrometer to take your measurements? IMO everyone that is using a tight neck chamber needs one.
 
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Steve, You must have neck turned this brass to .008 to have a loaded round of .259. Normal springback should give you a neck of .261 as Boyd said. The .257 bushing should give you grip on the bullet that you cannot turn with your fingers. I would guess your brass is thinner than .008. Are you measuring brass with a ball micrometer or a caliper? Calipers will read about .001 larger.
 
there is another issue...if his brass does measure 262...he probably does not have a 262 neck inspite of what it may say on the gun....more like 263,,,,poor machine work.
 
stevenorlando said:
Hello All,

I fire-formed some .220 Russian brass in my 6ppc (neck dia 0.262).
The fired brass measures 0.262".
A loaded round measures 0.259", so
I used a 0.257 bushing,
and I can insert a bullet with my hands.

Steve
Click to expand...

Start slowly, is this the order of your happenings?

Was the 220 Russian brass already neck turned? By you? By who?

Fired brass measuring 262 after firing is OK since your actual chamber neck is probably something over 262 (like 2623-2626" or so)

A loaded round measures 259-that means the brass has been turned (by someone).

You used a 257 bushing and can still insert a bullet by hand? OR, did you use a 257 bushing to load the round(s). THEN after firing you can insert a bullet by hand?
 
To me it sounds like his brass is springing back 1thou per side(2thou), which can be very normal with a lot of sizing applied(FL) & no annealing.
His chamber is .264, with fired brass springing back to .262(2thou).
His necks are springing back the same 2thou from the .257 bushing to .259(his loaded neck diameter), leaving zero tension.
 
For what its worth
I measured some of my brass from last year. They had about 8 firings each.
I have a .269 neck and the necks on fired cases measured .269
I sized a couple with a .266 bushing to see what spring back was and they measured .266 and one was .2665.
The loads in these cases was usually from 29.5 to 30.5 of N133.
 
Vern, I agree. All my Lapua brass springs back less than .001 after firing or after neck sizing. BTW, Lapua 220 brass is factory annealed. Waiting to hear from Steven.
 
Vern,
I have never seen a fired neck that had not sprung back from the chamber neck dimension, usually around .001 or a little less for new brass on a .262 ppc. I would be most interested in the tools that were used to take the measurements that are in the post that started this thread.
 
I used a ball micrometer and a digital micrometer for measurements. I think they are RCBS micrometers. I use a digital caliper to measure bullet lengths. All the measurements are what they should be. The neck wall thickness is about 0.009" The fired cases are 0.262". I can't figure out why I can't get enough tension on the neck to hold the bullet in when I push it with my hand. There is some kind of fault in my case prep process that I haven't figured out yet.

Steve
 
Hi Steve, in your original post, you state a loaded round is 259. In your last post, your turned brass is 009. if you take 259 and subtract 018 (2X009), that says your bullets are 241. That is not normal for 6MM Benchrest Bullets, what kind of bullets are you using ? And what do they measure on the pressure ring ?
 
I'm trying to load FMM precision bullets, the pressure ring is 0.24315.
 
Boyd Allen said:
Vern,
I have never seen a fired neck that had not sprung back from the chamber neck dimension, usually around .001 or a little less for new brass on a .262 ppc. I would be most interested in the tools that were used to take the measurements that are in the post that started this thread.
Click to expand...

Boyd I am using a digital caliper, and also have an electronic fowler digital mic. I also use 2 diff mitatoyo ball mics for neck turning.
I check all my instruments with a set of gauge blocks to make sure they are spot on before I start anything.

For what its worth. The last 2 years I have been shooting blue box lapua AND where I used to have to trim after every match just to keep them at.490 I now try to trim to .487 but all last year they never grew enough to get past .486
I even had 5 cases I used for 1 whole yardage and they only got out to .487 after 5 firings each.
I dont know if it has anything to do with the way I fireform and prep my brass or not but I do wish they would grow just a little.

I just did another 100 cases blue box same lot as last year with the same results so far. 2 firings and I still had to trim to .486
 
If your bump is .001 from a tight case, i would look at the amount that the body is reduced in diameter at the shoulder when it is FL sized. Being a bit of an oddball in that I use a Varibase die (we won't get into any of other potential perspectives) and given all that it does is the neck, bump the shoulder, and size the back half of the body, I am pleased to report that to get significant case growth, I have to screw up and leave the die set for old springy brass, when sizing fresh soft stuff. That will do it.
 
Steve, As Bob G pointed out, a loaded round with a.009 neck must be exactly .261 with a .243 bullet (6mm). Are you measuring in 3 different places with ball mike as you rotate the case? When you neck turn this brass do you have a close fitting mandrel? If not, you can get erratic cutting and different thicknesses around neck. Bob Z
 
I tried it with a 0.256 bushing, and it seems to be ok.

Steve
 
Simple enough

At this point, the only thing you have control over is the neck tension. If you want more tension, use a smaller bushing. Doesn't matter in the least what the measurements are given the current set of cases.
 
I was advised to remove the expander ball in the die, and it seemed to work. I'll be going to a local range on Friday with s BR shooter and check it out.

Steve
 
Steve, I didn't realize Redding S die used an expander ball. The expander will open the neck to the size of the ball regardless of the bushing size. It also overworks the brass and stretches the neck upward making cases longer. Wilson dies do not use an expander so you get what the size of bushing is minus about .001 springback. Bob Z
 
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