Neck clearance question

[Evan]

Hi all. I've seen it said here that a bullet should drop into a fired piece of brass. With my 22BR, I tried it out this morning and found that I have a snug fit in a fired case and the ID measures 0.224". Do I need to turn down my necks a little, or is this likely not causing any problems? I'm running a little tight on neck clearance in the chamber: 0.253" chamber vs 0.250 measured OD on a loaded round but had figured that was enough clearance.

Side note: I'm using a 0.249" bushing, so my neck tension is light. Bullets seat really smooth with uniform resistance. My groups have been ok, but not quite what I think is possible from this gun: ~0.5" at 200 yards.

 

[Texas10]

You might be seeing a little spring back on your fired case ID measurement. What is the OD of the fired case and how often do you anneal?

 

[tmwinds]

You're probably good on your clearance if you can push the bullet in with your finger. The neck expands to the chamber wall to release the bullet when fired but will bounce back slightly and gives a snug fit.

 

[Dusty Stevens]

For what its worth, with my experience when its right, the bullet should fall in. Shouldnt even have to push with 5lbs.

 

[Evan]

You might be seeing a little spring back on your fired case ID measurement. What is the OD of the fired case and how often do you anneal?

Haven't annealed, this is firing #2 on new Lapua cases. I've never annealed. I keep brass together and all on the same firing. When the shoulder starts to fight me, I get new brass. I've been giving that a hard think lately, though, and am considering annealing.

I'll have to measure the OD tonight on the fired brass. I think it should be 0.252".

For what its worth, with my experience when its right, the bullet should fall in. Shouldnt even have to push with 5lbs.

So would you try turning 0.001" off the OD?

Reason I'm asking is that this gun has displayed 1 amazing 0.07" group at 150yards, and a bunch of very closely paired shots in all the other groups. EDIT: example of paired shots:

That's 2 3shot groups at 200yards.

 

[Dusty Stevens]

Haven't annealed, this is firing #2 on new Lapua cases. I've never annealed. I keep brass together and all on the same firing. When the shoulder starts to fight me, I get new brass. I've been giving that a hard think lately, though, and am considering annealing.

I'll have to measure the OD tonight on the fired brass. I think it should be 0.252".



So would you try turning 0.001" off the OD?

Reason I'm asking is that this gun has displayed 1 amazing 0.07" group at 150yards, and a bunch of very closely paired shots in all the other groups. EDIT: example of paired shots:
View attachment 1115812
That's 2 3shot groups at 200yards.

Yes i would turn some off and see what happens.

 

[Evan]

You might be seeing a little spring back on your fired case ID measurement. What is the OD of the fired case and how often do you anneal?

I measured 5 different fired cases. All measure 0.250" OD. Does that even make sense?!? Do folks see 0.003" of spring-back on fired cases?

 

[rwj]

I measured 5 different fired cases. All measure 0.250" OD. Does that even make sense?!? Do folks see 0.003" of spring-back on fired cases?

FWIW, case neck ODs on my 6BR- .266” prior to seating bullet, .268” after seating, .271” after firing, chamber neck ID .272”

 

[Dusty Stevens]

I measured 5 different fired cases. All measure 0.250" OD. Does that even make sense?!? Do folks see 0.003" of spring-back on fired cases?

Not usually. You need more clearance. Youre close but a couple thou off

 

[47WillysGuy]

I measured 5 different fired cases. All measure 0.250" OD. Does that even make sense?!? Do folks see 0.003" of spring-back on fired cases?

I would say that your chamber neck is probably closer to 0.251 based on your 0.250” neck measurements. Usually 0.001” is the spring back measurement. What your getting is pretty tight. The reamer print will tell exactly what the neck dimension is or do a chamber cast.

And 0.003” of spring back makes no sense.

With 0.003” to 0.004” clearance your accuracy should improve.

 

[duanepa]

I think you’re onto something. The bottom line from the other thread on neck turn or not was...adequate clearance.

The old mantra from point blank BR was “cut thin to win”. It may not have been the thin necks as much as it was the additional clearance that led to the extra smidge of accuracy needed to agg lower, and hence win the match.
I guess the next question is whether you have tools to neck turn, or if you would have to start from scratch there?

 

[Dusty Stevens]

The old mantra from point blank BR was “cut thin to win”. It may not have been the thin necks as much as it was the additional clearance that led to the extra smidge of accuracy needed to agg lower, and hence win the match.

That is right but everybody always thought it was paper thin necks were the reason. It was meaning cut on the thin side for your particular chamber

 

[Evan]

I can neck turn. The big question is do I break down the 30 rounds I've got loaded to turn, or go shoot them. I'm leaning towards shoot them cause all I have is a kinetic bullet puller.

 

[Dusty Stevens]

If you can push a bullet in there by hand go ahead and shoot them just turn em after

 

[Kracken McGraw]

In Theory though if you only had two thousandth’s neck clearance and can’t push Bullet in by hand on fired case, if these rounds are all loaded the same then they should still have the same point of impact.

 

[duanepa]

I wish we knew your reamer spec. Does your smith have the print? I think you would be ok to shoot what you have loaded, provided you can push a round up into the chamber with your finger and there is no catching or resistance. Not on the hottest day of the year either...

 

[Evan]

I wish we knew your reamer spec. Does your smith have the print? I think you would be ok to shoot what you have loaded, provided you can push a round up into the chamber with your finger and there is no catching or resistance. Not on the hottest day of the year either...

It's the grizzly stocked PTG reamer with a 253 neck and 100 freebore. I'll post the print tonight.

I can close a stripped bolt on a loaded round with just a tiny bit of resistance at the very bottom of the bolt closing. If I bump the shoulder another 0.001, there is no resistance.

I'm also not seeing early or erratic pressure with my loads.

 

[Evan]

I should have linked this up from the start:
http://forum.accurateshooter.com/threads/my-new-22br.3981971/
I've been logging my progress with this new round there.

 

[Steve Ladino]

Hi all. I've seen it said here that a bullet should drop into a fired piece of brass. With my 22BR, I tried it out this morning and found that I have a snug fit in a fired case and the ID measures 0.224". Do I need to turn down my necks a little, or is this likely not causing any problems? I'm running a little tight on neck clearance in the chamber: 0.253" chamber vs 0.250 measured OD on a loaded round but had figured that was enough clearance.

Side note: I'm using a 0.249" bushing, so my neck tension is light. Bullets seat really smooth with uniform resistance. My groups have been ok, but not quite what I think is possible from this gun: ~0.5" at 200 yards.

I have .0005 neck clearance all around in my 6 BR chamber ( absolute minimum ) , no problems in my last four barrels with this reamer. My bullets fit pretty snug in fired cases.

 

[Dusty Stevens]

I have .0005 neck clearance all around in my 6 BR chamber ( absolute minimum ) , no problems in my last four barrels with this reamer. My bullets fit pretty snug in fired cases.

I tried that one time. They used to call that a “fitted neck”.