Puzzled (rounds not chambering)

[Bocephus]

Post read in haste. Apologies if I missed this question:
Are you using a bushing die?

 

[SGK]

yes

 

[abersfelderami]

Carbon ring? and uneven boltface from leaking primers.

 

[3Sigma]

Can you use a borescope and see where the bullet hits the chamber? Use sharpie, dykem, etc. on the bullet to mark chamber. Maybe out of round?

Also, any way to measure runout on one of these rounds?

Just looking for evidence.

 

[SGK]

I recorded a video via my Teslong if it helps with the carbon ring question (apologies for my kids screaming in the background)

 

[SGK]

Run out is 1-2 thou (generally); less than 1 thou on the one I have seated more deeply now (in my last pic).

 

[bozo699]

You

I recorded a video via my Teslong if it helps with the carbon ring question (apologies for my kids screaming in the backgroun

You do have a carbon ring sir!….
Wayne

 

[bozo699]

As to the brass (again):

So as mentioned I'm using a single box of Lapua brass. Started with 100 cases. 1 was used for the dummy round to find 'touch' using the Wheeler method. 1 was damaged or lost at some point. That leaves 98 3x fired cases. All prep'd in an identical manner (including bumping the shoulders). I loaded 50 before heading to the range today. As far as the cases are concerned, the only differences between these 50 and the 48 left in my cartridge case at home are: primed, mandrel through necks for 1 thou tension, powder added and bullet seated. All, every single one, of the 48 that were not loaded chamber without issues. All of the cases that I fired today chamber without issues (and without resizing or anything). If it were a 'shoulder bump issue' I'd expect to have an issue with at least one of the 48 that were prepared in the same way and didn't have a bullet seated in it.

"He means what is called the .200 line right above the base." As best as I can measure this is 0.470".

I measure shoulder bump after resizing to confirm the desired bump. I use my Whidden shoulder bump gauge for this.

(FYI my bolt is controlled round feed. There is no ejector.)

Carbon ring / "seat the one that won’t chamber at least .005 more"

I've looked with my Teslong and there's nothing obvious. Perhaps I need to look more carefully. Would one expect a carbon ring after 300 rounds? (The scuff that appears on the bullet if I give the bolt a firm push doesn't appear all around the bullet.) I took one of the rounds that I couldn't chamber and step by step seated the bullet deeper. Seating 12 thou deeper and it chambered but the bullet is still sticking on extraction.

It looks to me that your methods are good. All we’re trying to do is help sometimes people skim through without fully reading so I know it’s frustrating. Those are not land marks on your bullet. I can’t tell by the pictures although there very good pictures but it almost looks like there not trimmed or chamfers well enough and that’s probably just glare but worth looking at. Also in your video there’s a definite start of a carbon ring on the start of your lead. Don’t know if it’s enough to scrape your bullet or not. I’m convinced with your method of brass prep it’s not s shoulder bump problem and if it was at the .200 line you would have clickers and you haven’t mentioned that. Give her a good scrubbing with some jb bore paste or something similar and your normal cleaning methods and re scope it. I think this is fixable without much work.
Best of luck and remember we’re not there but we’re here trying to help and we’re on your side
Wayne

 

[SGK]

Not many of the cases needed to be trimmed this go around.

I thought a carbon ring appeared in the freebore area rather than throat/landes. I will get out the jb but I also would like to understand better what I'm looking at with the borescope.

(I have JB Bore Bright which I suspect is what you mean)

 

[SGK]

And I do very much appreciate everyone's help!

 

[Webster]

At 20 thou deeper I'm getting an easier bolt close. Also, you can now see better the scuffing on the bullet, always in the same area butt spreading further back as I seat deeper. It puzzles me that as I have randomly placed the cartridge in the action why the scuffing isn't forming all around the bullet...

View attachment 1344052

The scuff mark looks much wider than a rifling land? Your photos seem to show no appearance of chamfering, but it probably is not related to the problem. Do you trust your gauge? I would seat the bullets 10 thou deeper and see if the problem goes away. A lot of scratch marks on the case neck? Probably from not chamfering to remove what looks like a high ridge all the way around the neck.

 

[Webster]

I think must be differences in bullet curvature between above where my Forster Datum Dial kit measures. On the bottom two rounds below you can see where the lands have scuffed the bullet. My datum Dial Kit measure a few mm below this point. You can see where the Datum Dial has marked the bullet versus the scuff.


View attachment 1343999

Why does the oxide layer look rubbed off on the bottom case neck?

 

[Coyotefurharvester]

If you pull the bullet from 1 that Doesn't chamber, then try to chamber the brass. If the brass chambers the bullet was the issue. If not sizing of the brass incorrect or when seating the bullet the case was distorted(inadvertently crimped?).

 

[243winxb]

Set fl die to touch shell holder.

 

[SGK]

"I would seat the bullets 10 thou deeper and see if the problem goes away."

It takes a lot more than 10 thou for the issue to go away. Closer to 30-40 thou but some would appear worse than others.

"Why does the oxide layer look rubbed off on the bottom case neck?" I assume you are looking at the bottom case of the pic with three. On one or two cases my bushing scuffed oxide off the case neck. Probably lack of lube. Yeah when you zoom in this much in a photo I could likely have chamfered more firmly. But there is plenty of clearance in the neck dimension. Loaded rounds measure 0.269" versus a reamer dimension of 0.272".

I got out the JB Bore Bright and gave things a good scrub. It hasn't helped in a noticeable way.

I pulled the bullet from one of the loaded rounds that wouldn't chamber. The case chambers easily.

 

[bozo699]

Not many of the cases needed to be trimmed this go around.

I thought a carbon ring appeared in the freebore area rather than throat/landes. I will get out the jb but I also would like to understand better what I'm looking at with the borescope.

(I have JB Bore Bright which I suspect is what you mean)

Somewhere around 13 seconds into your video in this picture of your video on the right side there’s a dark ring just past the neck, where the neck ends and your lead starts that’s the start of a carbon ring . It’s very narrow but very distinct
Wayne

 

[bozo699]

Oh I don’t know what jb bore bright is, jb bore paste comes in a small round container like carmex and it’s like jewelry rouge it’s a abrasive built for removing carbon I like to put a little bitches bore shine with it when I scrub the throat area
Wayne

 

[K22]

I don't believe this is a sizing issue based on what has been posted thus far.

I believe this is bullet seating issue. Measure about 5 bullets to determine the range of max COL. Selected the lowest measurement and back off .020 which should place you well off the lands even with variations in the bullet ogives.

The measurement method must be based on the bullet ogives not the overall length of the cartridge from the base of the case to the point of the bullet. I use a version of the Frankford Arsenal tool but any tool that measures off the bullet ogive will suffice.

The other issue is severe out of round bullet judging from the marks on the bullet, but I don't think that would cause excessive chambering issues.

 

[Lone Hunter]

Do like Wayne says with JB bore paste. Put a patch around a brush and use JB and some type of carbon cutter at the same time and scrub the barrel real good for the first 10-12” of the bore. Some guys use a carbon remover and spin a bronze brush on a drill. Good Luck hope you get it taken care of.

 

[SGK]

Oh I don’t know what jb bore bright is, jb bore paste comes in a small round container like carmex and it’s like jewelry rouge it’s a abrasive built for removing carbon I like to put a little bitches bore shine with it when I scrub the throat area
Wayne

This is what I have (The material is crimson in color)

J-B® BORE BRIGHT | Brownells

A micro-fine bore cleaning and finishing compound that works as both a cleaner and a final polish to help keep barrels free of fouling and shooting their absolute best. Regular use gives your barrel a mirror-like finish that helps prevent the buil...

www.brownells.com

There's JB Bore Compound

J-B® NON-EMBEDDING BORE CLEANING COMPOUND | Brownells

The original, time-proven formula developed by Jim Brobst and produced under exclusive license. J-B has been getting burned-on, caked-in powder residue and copper jacket fouling out of gun barrels since the 1960’s, and hasn’t damaged an inch of ri...

www.brownells.com

There is no product that I can find that is labelled JB Bore Paste.

I will scrub away some more tomorrow.