Forming 22BR from 6BR - Strange

[RAG]

I've been playing this game for over 20 years but I'm stumped here. I've encountered a strange phenomenon when forming 22BR from new 6BR Lapua brass. I'm using a Harrels 6BR FL die (custom matched to my reamers), with a .2500 Redding bushing. The necks are coming out about .245 on the majority of the neck, with a little flare at the very end of the mouth, flared out to about .2490. I was expecting the necks to rebound a little and end up closer to .2505-.2510. Yet, after sizing, I can push the bushing over the neck by hand, with a little play to boot.

I'm betting everything will size as expected after I fire once and FL size again with the .250, but I have 400 pieces of brass here, so I'll probably just get a larger bushing size until I get a more reasonable .0015-.0020 neck tension. But I can't figure out how the necks are coming out narrower/smaller than the bushing used. The die body is a perfect/tight fit to the virgin Lapua brass, by design, with zero play. And I measured the bushing inside diameter comes to .250 spot on.

FWIW, I was simply trying to confirm that my on-order 22BR reamer had property neck diameter for no-turn tight neck, which it does, as my loaded rounds come to .2510 - .2515 and my reamer will be .2535 (hopefully, lol).

Thanks!

 

[Toolbreaker]

My first thought would be that the bottom ID of the bushing is contacting the neck/shoulder junction of the brass and squeezing the neck down slightly at the top of the ram's stroke. You might try setting the bushing a little looser (higher) in the die and see if that fixes it.

 

[MQ1]

I had the same observations forming 6.5x47 Lapua to 6mm. The solution for me was to expand the neck and resize again….I don’t remember the exact details, but I think I annealed after the first firing after that.

MQ1

 

[DocDoc]

What is the differenced between fired expanded neck and the diameter of the bushing? If there is a large enough difference, the bushing will squeeze more than its nominal size.

 

[RAG]

My first thought would be that the bottom ID of the bushing is contacting the neck/shoulder junction of the brass and squeezing the neck down slightly at the top of the ram's stroke. You might try setting the bushing a little looser (higher) in the die and see if that fixes it.

Well, I sized 1/2 the neck here and got the same phenomenon. I just don't know a .250 bushing can squeeze a nexk down to .245...it defies logic and physics.

 

[RAG]

I had the same observations forming 6.5x47 Lapua to 6mm. The solution for me was to expand the neck and resize again….I don’t remember the exact details, but I think I annealed after the first firing after that.

MQ1

Yeah. As for the lip at top...that must have to do with the how thw brass was annealed and difference in elasticity/ rebound. Really I have 2 weird things going on at once.

 

[RAG]

What is the differenced between fired expanded neck and the diameter of the bushing? If there is a large enough difference, the bushing will squeeze more than its nominal size.

I'm sizing new 6br brass to 22, so the brass is .266 at the neck to start, I'm using .250 bushing, and the result is .245 outside diameter (except .249 at leading edge of the mouth).

 

[ronemus]

I've seen and read of this phenomenon many times. Brass can extrude through the bushing (or a die neck) when the brass OD is much larger than the ID, and end up smaller or larger than expected. The usual advice is to size in steps of 0.003-4", Were you trying to go from 6mm to .22 in one step?

 

[RAG]

I've seen and read of this phenomenon many times. Brass can extrude through the bushing (or a die neck) when the brass OD is much larger than the ID, and end up smaller or larger than expected. The usual advice is to size in steps of 0.003-4", Were you trying to go from 6mm to .22 in one step?

Yeah, one step since I was was only going down one caliber, which I've before in other cartridges without issue. But, I bet your right in that I might avoid the problem if I neck down in a couple steps.

Also, I just took on older piece of 6BR brass...probably 15yrs old with 10 firings or so, and necking it down in one step with .250 bushing lead to neck diameter of. 248; still a bit smaller than bushing, but a ton better than .245. And no lip issue.

 

[ronemus]

Yeah, one step since I was was only going down one caliber, which I've before in other cartridges without issue. But, I bet your right in that I might avoid the problem if I neck down in a couple steps.

Also, I just took on older piece of 6BR brass...probably 15yrs old with 10 firings or so, and necking it down in one step with .250 bushing lead to neck diameter of. 248; still a bit smaller than bushing, but a ton better than .245. And no lip issue.

You can probably go down in one step if you use a full length non-bushing die; that setup is much better behaved.

 

[RAG]

You can probably go down in one step if you use a full length non-bushing die; that setup is much better behaved.

Interesting. I happened to have a ,260 bushing, and Forester 6BR Neck Sizer thats about .260...this step resulted in .259 at the neck. I also had a. 256 bushing; this produced .255, and then my .250 for 3rs step yielded .249, and only slight flare at the mouth of about .250...so this produced very reasonable neck tension and will likely be my routine.

Thanks!

 

[RAG]

The other advantage of sizing in these 3 steps, for me anyhow, is that my runout is just .001-.002. I was getting .003-.004 when sizing in one step. Now I'll just have to see if the bushing is able to get far enough down the neck to chamber...it sort of has a small "false shoulder" that might actually work out perfectly.

 

[RussellJ]

From my notes on making 22BR Brass from Lapua 6BR Norma brass:

(1): Full length size brass case with .255” Redding bushing

(2): Full Length sized brass case with .246” Redding bushing

(3): Expanded the neck with K&M mandrel

(4): Neck turned last .050” (+/-) of neck with K&M tool

 

[lpreddick]

Well, I sized 1/2 the neck here and got the same phenomenon. I just don't know a .250 bushing can squeeze a nexk down to .245...it defies logic and physics.

I had this same problem and think I solved mine. I believe when the neck's lip contacts the bushing it does not enter it and as more ram pressure is applied, the neck sorta collapses inward, then goes into the bushing. If you expend your photo of partially sized neck i get the impression of an inward curve from the lip, which is correctly sized. I annealed mine and did them in steps and they measured as expected.

 

[Hohn]

It’s a flaw in most bushings that they lack taper in the ID. The Wilson and SAC bushings have lead in taper and work better

 

[RAG]

From my notes on making 22BR Brass from Lapua 6BR Norma brass:

(1): Full length size brass case with .255” Redding bushing

(2): Full Length sized brass case with .246” Redding bushing

(3): Expanded the neck with K&M mandrel

(4): Neck turned last .050” (+/-) of neck with K&M tool

Yeah, depending on how it chambers up, I was giving thought to oversizing and then using expander mandrel to fix the unintended false shoulder on the nexk at junction of shoulder.

And then you turn bottom section to eliminate the donut? It does get pretty thick and the very bottom of neck...mine jumps from. 013 to .017 quickly. Hoping it doesn't impact me,, since I'm only gonna shoot 53s and 55s.

 

[RussellJ]

Yeah, depending on how it chambers up, I was giving thought to oversizing and then using expander mandrel to fix the unintended false shoulder on the nexk at junction of shoulder.

And then you turn bottom section to eliminate the donut? It does get pretty thick and the very bottom of neck...mine jumps from. 013 to .017 quickly. Hoping it doesn't impact me,, since I'm only gonna shoot 53s and 55s.

RAG;
Yes, I neck turn the last .050" or so do to the neck bushings pushing the brass back to the shoulder. When shooting or hunting I definitely try not to loose any of my brass cases. I have too much time and effort into them.

 

[cdngary]

Remove the seating stem in your seating die and run your 6br brass into the die to start the sizing then into your 22 sizing die to finish. Works great for a .254 no turn neck. Worked great for me.

 

[boltfluter]

Remove the seating stem in your seating die and run your 6br brass into the die to start the sizing then into your 22 sizing die to finish. Works great for a .254 no turn neck. Worked great for me.

Exactly what I do. A seating die makes for a great intermediate step. Many ways to skin this cat.

 

[RussellJ]

Remove the seating stem in your seating die and run your 6br brass into the die to start the sizing then into your 22 sizing die to finish. Works great for a .254 no turn neck. Worked great for me.

On Youtube there is a video using the exact same method. I believe one of the guys from the DASHER DOME made the video. The next time I need to form 22BR brass I'm going this route.