Chamber clearance issues.

[joelpend]

You have to determine what the problem is before you can correct it. A chamber cast is a good place to start but that is not easy for everyone to do. If you have someone local that builds rifles I bet they could determine the problem pretty quick.

 

[DShortt]

Hence why I recommended also getting a throat reamer.

If your remotely competent and careful doing both is a simple operation.

I'd agree with that but if the chamber is cut short is the OP going to stick a piece of brass after he throats it and neck reams it?

Why chance it?

All we know thus far is the headspace was excessive. Since a recoil lug can change that who knows what the chamber really is?

 

[joelpend]

A throating reamer cuts only the freebore/leade. I do not see that the bullet has a clearance issue. A neck and throating reamer combined could solve a problem "if" it is a tight neck issue.

 

[codybrown]

I don't believe I'll run into a throating issue, I'm limited to a short oal due to the constricting factory magazine length. The bullet I seated was a 200gr sierra, and that'll be the heaviest I'll use in this rifle. I also colored another round with a sharpie and the bullet didn't make any contact when chambered.

 

[Schippergreg]

Are you using new brass or has it been previously fired?

 

[codybrown]

This is 1x fired nosler brass that I full length resized.

 

[codybrown]

If it is truly the neck a neck reamer would make short work of it.
It’s a different reamer than a throat reamer

They make throat, neck and throat/neck reamers.

I personally would rent a neck and throat reamer and set them individually.

Most 300 rums have a short freebore so you could possibly use a combination neck/throat if the geometry is close.

You can actually get a decent idea of neck length with a depth gauge and really even a set of calipers.
Could be a worn reamer with a tapered or short neck.

From my understanding on ptg's website the throat reamer is meant for diameter not length.

 

[DJSBRS]

It sets the barrel back further into the action.

Provided that the bolt clearance is not an issue.

DJ

 

[SKWERLZ]

From my understanding on ptg's website the throat reamer is meant for diameter not length.

That would still fix the OP’s issue if it’s a tapered neck he’s dealing with
The one time I used a neck reamer was when fixing a a chamber that was cut with a bad reamer that cut a short and tapered neck.

 

[codybrown]

That would still fix the OP’s issue if it’s a tapered neck he’s dealing with
The one time I used a neck reamer was when fixing a a chamber that was cut with a bad reamer that cut a short and tapered neck.

I am the OP. I got a couple more pieces of different brand brass today, when I get home I'm going to see what they do.

 

[SKWERLZ]

I am the OP. I got a couple more pieces of different brand brass today, when I get home I'm going to see what they do.

One question then is will a empty case freely seat in the chamber?

 

[codybrown]

Ok, here's the update:

I got my hands on a couple pieces of both Barnes and Remington fired brass. No idea how many times fired they were. Sized them with a full length sizer and measured them, tried chambering them, then seated bullets the exact same as with the Nosler brass. I also tried chambering the Nosler brass with no bullet seated. The Remington and Barnes both had no issues chambering both with and without bullets. I colored the cases as well and they still touch on the case mouth, but the bolt is easy to close. The Nosler brass chambers hard both with and without a bullet seated.

Here's the measurements of the brass:

Remington
2.840 OAL
.3365 neck diameter no bullet
.3390 neck diameter loaded
.0165 neck thickness

Barnes
2.8440 OAL
.3370 neck diameter no bullet
.3385 neck diameter loaded
.017 neck thickness

Nosler
2.837 OAL
.3380 neck diameter no bullet
.3390 neck diameter loaded
.017 neck thickness

Pic of the brass, Barnes is on the left, Remington on the right.

 

[codybrown]

One more thing I thought I'd try. I also have a factory Browning 300 rum. Just for fun I tried all 3 pieces of loaded brass through that. The Nosler chambers, but there is a small amount of resistance closing the bolt. With both the Remington and Barnes rounds the bolt closes like it's an empty chamber.

 

[ronemus]

It looks as though your chamber has a "no turn" neck for some brass, but the Nosler brass is just a bit too thick in the neck to chamber; that means your Barnes and Remington brass have very little clearance. Do you know what the reamer's neck diameter was? It looks as though you'll need to turn at least 0.001" off your brass, more if you don't want to monitor your brass very closely. Turning off 0.002" would create total clearance of 0.004" which would make it easier to maintain your brass - that's small enough to be easy on youor brass and give good accuracy, bit less finicky than 0.002" clearance would be.

 

[SKWERLZ]

Is the brass showing interference marks all around the mouth?
I’m suspecting a worn/damaged reamer, any history of reamer?

 

[DShortt]

If this barrel has been fired you might check for a carbon ring at the end of the case mouth also.

 

[codybrown]

The story I got was that it was supposedly rechambered by Hart. No paperwork and no history other than hearsay, so I have no idea on the reamers history, condition, or specs.

The first issue I had was that the rifle was originally a 300 win mag that was rebarreled. When I initially got it, the brass wouldn't fit through the bottom of the action and I had to get the opening milled out.

The second issue was the headspace being out of spec.

The third issue is what im dealing with now. Hopefully this is the end......


To the question about contact points on the brass, it isn't consistent all the way around. I would say where it touches is random and varies in length and depth of contact.

 

[codybrown]

If this barrel has been fired you might check for a carbon ring at the end of the case mouth also.

The barrel has been fired, but I don't believe very much. I thoroughly cleaned it when I first got it and initially checked the headspace. There's no buildup in the barrel or chamber at all.

 

[SKWERLZ]

Do you have a bore scope?

 

[codybrown]

Do you have a bore scope?

I'm going to see if I can get my hands on one tomorrow. That's on my list now that I'm at this point.