Neck clearance question

[Evan]

So a little data to throw on the pile:

I turned 9 necks down to a neck OD of 249 and shot them this morning. The fired OD is once again 250. A bullet will now slip into the neck of a fired, turned case with only the slightest drag going in. Accuracy was no better or worse vs unturned. I'm thinking I need to talk to the gunsmith and see if he will measure/double check his reamer. I wonder if it is a 250 or 251 neck reamer and the reamer was mislabeled/ground wrong. Right now, I'm planning to turn all of it down to 248 and move on.

Either way, I achieved some wonderful accuracy with Varget and un-turned brass this morning: http://forum.accurateshooter.com/threads/my-new-22br.3981971/page-2#post-37542368

 

[Dusty Stevens]

So a little data to throw on the pile:

I turned 9 necks down to a neck OD of 249 and shot them this morning. The fired OD is once again 250. A bullet will now slip into the neck of a fired, turned case with only the slightest drag going in. Accuracy was no better or worse vs unturned. I'm thinking I need to talk to the gunsmith and see if he will measure/double check his reamer. I wonder if it is a 250 or 251 neck reamer and the reamer was mislabeled/ground wrong. Right now, I'm planning to turn all of it down to 248 and move on.

Either way, I achieved some wonderful accuracy with Varget and un-turned brass this morning: http://forum.accurateshooter.com/threads/my-new-22br.3981971/page-2#post-37542368

Its not at all uncommon to find the neck dia wrong on a reamer. I use pin gages to check them because you cant really measure a reamer and figure out what itll cut to

 

[rwj]

Its not at all uncommon to find the neck dia wrong on a reamer. I use pin gages to check them because you cant really measure a reamer and figure out what itll cut to

Yup, plus one has to account for wear on the flutes...

 

[rwj]

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.

Is there less neck clearance than bullet interference fit? If yes, does this result in a detectable increase in chamber pressure?

 

[Evan]

Is there less neck clearance than bullet interference fit? If yes, does this result in a detectable increase in chamber pressure?

I haven't seen unusual pressures, but I also don't run up near the top where you might expect to see signs when slightly higher pressure is encountered. It could definitely explain some of the random shots I've been observing though!

So the light interference fit is at 0.250 loaded, a snug slip fit was achieved at 0.249 loaded. I turned the necks on 50 cases down to 0.012 (0.248 loaded) and saw considerable variations across the cases. For about 90% of the cases, this 0.002 cut only cleaned up 3/4 of the neck. A few cases it hardly touched, and a few cases it cleaned the entire neck.

I'm headed back out tomorrow and I've got 15 unturned cases loaded with 4350 left to shoot, and I have 41 turned cases ready to load up to shoot. I'm thinking about loaded up some more 4350 to do a side by side with the unturned, but my results with Varget were so good on Friday that I'm not sure if it makes sense to continue with any of the other powders (except I only have 2lbs of Varget and 5+lbs of 4350).

 

[Dusty Stevens]

Youll have way less flyers once you get enough clearance. Dont even experiment just get more clearance. Its 100% proven that not enough clearance causes flyers but too much clearance never hurt anything. Trying to find the exact point the flyers go away is just a wasted range session

 

[Homerange]

Youll have way less flyers once you get enough clearance. Dont even experiment just get more clearance. Its 100% proven that not enough clearance causes flyers but too much clearance never hurt anything. Trying to find the exact point the flyers go away is just a wasted range session

OK, I'll bite.

Decades ago when I first started handloading we used a Lee Target handloading set with which after full insertion of the case into the die you then applied the inside neck reaming tool that set the neck tension.
Trouble with this Lee set was it was set for a much smaller neck diameter than the 308 Anschutz we used it on and best grouping obtained was in the 2" range. Still, it shot a lot of deer in the heavy bush hunting that is the norm here in NZ. Even some years later after getting it rebarrelled it never shot any better until in frustration I tried a set of old unbranded FL dies and some range pickup brass....and prepped like any other.
The result was like night and day as with the Lee set and inside neck reaming there was far too much neck clearance. Today with this same hunting rifle and with LCD brass prep it consistently shoots sub 1/2" groups with a variety of handloads.
Too much neck clearance never hurt anything = BS.

 

[Dusty Stevens]

OK, I'll bite.

Decades ago when I first started handloading we used a Lee Target handloading set with which after full insertion of the case into the die you then applied the inside neck reaming tool that set the neck tension.
Trouble with this Lee set was it was set for a much smaller neck diameter than the 308 Anschutz we used it on and best grouping obtained was in the 2" range. Still, it shot a lot of deer in the heavy bush hunting that is the norm here in NZ. Even some years later after getting it rebarrelled it never shot any better until in frustration I tried a set of old unbranded FL dies and some range pickup brass....and prepped like any other.
The result was like night and day as with the Lee set and inside neck reaming there was far too much neck clearance. Today with this same hunting rifle and with LCD brass prep it consistently shoots sub 1/2" groups with a variety of handloads.
Too much neck clearance never hurt anything = BS.

Neck reaming? Lee loaders? Im not sure if you bit the right hook. We’re not even in the same book

 

[duanepa]

Measure three times, check twice, cut once...

 

[Evan]

OK, I'll bite.

Decades ago when I first started handloading we used a Lee Target handloading set with which after full insertion of the case into the die you then applied the inside neck reaming tool that set the neck tension.
Trouble with this Lee set was it was set for a much smaller neck diameter than the 308 Anschutz we used it on and best grouping obtained was in the 2" range. Still, it shot a lot of deer in the heavy bush hunting that is the norm here in NZ. Even some years later after getting it rebarrelled it never shot any better until in frustration I tried a set of old unbranded FL dies and some range pickup brass....and prepped like any other.
The result was like night and day as with the Lee set and inside neck reaming there was far too much neck clearance. Today with this same hunting rifle and with LCD brass prep it consistently shoots sub 1/2" groups with a variety of handloads.
Too much neck clearance never hurt anything = BS.

I think the difference is that neck reaming doesn't work. I've tried it 2 times in my life, and both times it trashed the brass. I think the unsupported neck, rather than cut cleanly, gets pulled and distorted by the flutes in the reamer, resulting in a neck that is not round or concentric with the OD of the brass neck. I think this was the crappy accuracy you were seeing, not the increased clearance in the chamber. Just a guess though. I still have the reamers; my grandpa handed them down to me. They sit in the drawer and are never used due to the results of my 2 experiments.

 

[338 dude]

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 like having 3 or even 4 thou neck clearance I feel you are a little tight

 

[AlNyhus]

I think the difference is that neck reaming doesn't work. I've tried it 2 times in my life, and both times it trashed the brass.

Cutting the neck i.d. is beneficial in certain situations. To do it properly requires tools that aren't available in the marketplace, however. Also, unless the outside of the neck is turned concentric to the inside of the neck, you will have brass issues.

Very few hand loaders are willing to invest the time or resources to make the inside of the necks as good as they can be.

And in most situations, it's not needed.

Good shootin'. -Al

 

[gunsandgunsmithing]

I've never seen too much clearance hurt accuracy but I have seen it with too little.