Criterion 223 match with short neck

[fatelvis]

I just installed a Remage barrel from Northland in 223 Match w/.090” throat. It has plenty of neck clearance for unturned Lapua brass (.25” loaded, .254/5 fired), but will not allow a bullet to slide into the fired neck. The brass is trimmed to 1.755”. I see that it is caused by the chamber being unusually short. It does not allow the very end of the mouth to fully release the bullet, and acts as sort of a crimp. Does anyone else see this, and is this common? Thanks guys

 

[Ackman]

With a Remage setup you screw the barrel in and set the headspace yourself. From what you're saying, sounds like the barrel is screwed in just a little too far making the chamber length too short, crimping the end of the case in the end of the chamber where it steps down to the throat. Loosen the nut and back off on the barrel just slightly, about 1/8 turn (.0075"). Tighten the nut again taking care not to tighten the barrel when you do it.

 

[Nick LaFave]

If the headspace was that short he wouldn’t be able to chamber a round.
Chamber length should be 1.770+ for a 1.760 trim to length.
Get a chamber length gauge from Sinclair’s and check the length of your chamber.
Was there signs of pressure?
What’s the load?
Is there soot all the way up the neck?

 

[fatelvis]

I used my Teslong bore scope down the bore while a fired case was in the chamber. The mouth was very close to the end of the chamber's mouth.

 

[dolek]

Are you shooting light loads ?

Also,did you use gauges or brass to set headspace ?

 

[jepp2]

but will not allow a bullet to slide into the fired neck.

The majority of what I shoot doesn't allow a bullet to slide in the fired case neck. Many different calibers and actions. And none are "pinched" at the end of the chamber. And some are on my 25-06's that I load to near 65K pressure. Close visual exam shows the case mouth to not be the same diameter as the rest of the neck. I've been tempted to take a good close up picture, to have available to share. And all of these are no turn necks, with normal clearance as you mentioned. FWIW

 

[Hohn]

I used my Teslong bore scope down the bore while a fired case was in the chamber. The mouth was very close to the end of the chamber's mouth.

very close? Or past? To cause the problem you are describing, the chamber neck would need to be shorter than the brass.

My savage OEM barrel will also leave fired cases with a little bit of residual neck tension on a bullet. This is an artifact of having a saami-min neck diameter of ~ .254 and thick(ish) neck brass. Not necessarily an indicator if the neck being too short.

Now, if there is an observable crimp on the neck after firing, and this crimp is the only cause of the bullet tension, you might indeed have a chamber neck too short, if the headspace is correct. Do you have go and no-go gauges?

 

[Texas10]

I used my Teslong bore scope down the bore while a fired case was in the chamber. The mouth was very close to the end of the chamber's mouth.

If a visual check with the Teslong shows the case mouth is not jamming into the throat, and the base to mouth measurement is within spec, you're good. Shoulder bump obviously does affect the case mouth position within the chamber as you've probably seen with your Teslong. So trim for clearance regardless.

I've noticed that 223 cases will leave a slight choke at the mouth when fired. Are these new cases, used but annealed cases? If they're hardened from repeated use, springback may be the issue. Simply anneal them.

 

[fatelvis]

I set the chamber using a go gauge, and it is within spec. They are loaded to medium to high levels, and the brass is once fired. I’m going to trim a few cases shorter than normal, load them up and shoot them. I will inspect them afterwards, and hopefully they won’t have the pinched mouth syndrome.

 

[MGYSGT]

I usually trim my brass neck length to 10 thou under specs. Just saves a lot of trouble, especially in the AR mode. It doesn't really affect groups as long as they are all the same. I never crimp cartridges so that is not an issue.

 

[Zero333]

I doubt the chamber neck is short.
Did you chamfer the brass before loading ?

 

[chop house]

this is a repost from a year or so back when i responded to another thread:

" was struggling with some 22-250 loads smoking the necks even at midrange pressures. also had way too much vertical showing. measured case necks using tubing mic and seeing over 0.002 non-uniformity.

so, a while back i thought i was 'over' chamfering/deburring thus turning the mouth into a sharp knife edge, and i started going easy with the debur tool. too easy it turns out. had a neck fail so inspected under microscope:

non-uniform swaged lip on case od:

luckily i had a few prepped yet unloaded cases from the same batch:

so, yeah.... inspect with a magnifier to check your procedures. and keep your cutters sharp and your brass not too soft"