Gunsmithing M700 difficult extraction

[JMGlasgow]

New Criterion Chromoly 6.5 Creedmoor barrel, Alpha brass (twice fired on old Criterion SS barrel) shoulder bumped .003"

I'm having issues with case extraction no matter the powder charge. I've tried new Hornady dies, and scrubbing the chamber with a chamber brush.

Almost every fired case requires tapping the bolt with a plastic face mallet to get the case to extract. I never had to do this with my last barrel.

There are no apparent burrs or irregularities I can see with my eyes. There are however bright areas on the cases near the case rim.

The little blueish lines are light reflections.


What can be done to solve this? I have an inquiry in to Criterion, hopefully I won't need to send it back to them. They don't stock chromoly M700 prefit barrels.

 

[LRI]

You might try a base die. Sucks, as this should run to standard out of the box, but shit does happen sometimes. First, check to see how a FL sized case goes in by itself. If it chambers effortlessly, then it stands to reason that it should also come out just as easy. X2 with "vanilla" hand loads or commercial ammunition.

I mean, it's a 308. Kinda like an old school small block chevy. -Really hard to fuck it up.

The good new is, there does not seem to be any evidence of "muffin top" along the webline of your brass. It shows that the chamber is not grossly oversized or that your brass is way under. It might just be a case of them being really close to one another from the start and the hardness just isn't allowing it to spring back as much as you'd like.

Before getting too carried away, maybe throw some other stuff at it. Winchester for instance, typically comes in around .463" at the webline. - .471" is nominal on most SAAMI recognized prints. European brass like Lapua/Norma/RWS is almost always right at .467-.468. If by chance you are north of those numbers, that would explain the sticky bolt.

As you stated, no indications of any pressure. Just double check. Primer crater, flattening, ejector swipe, case swelling at the web, heavy brass transfer to face of bolt, tick at the top of rotation. All classic signs.

If by process of elimination all your seeing is some burnishing at the web, then it kinda leans towards either brass that's "fat" or a chamber that is a smidge tight.

Hope this helps.

C.

 

[JMGlasgow]

New ammo and sized cases chamber with no resistance, and extract with no resistance. It's also a 6.5 Creedmoor, not a 308. This rifle craters every primer it has struck, and I've had no issues with it so far. Primers aren't flat, and no ejector swipe either. There is brass transfer only because the case is sticking and the bolt head is rotating while the case isn't.

I'll probably end up sending it to your for a Tig and Time service. I have 3 RR prefix M700's that need it.

 

[jd5521]

You haven’t told us if you’re using the same load data from your old barrel or not?

 

[Ksracer]

The chamber the brass was previously fired in was probably a hair larger at the base than the new one, and now the web has a "memory" in the area that your resize die can't quite remove. When it's fired in the new chamber, it try's to spring back to the old diameter and sticks slightly. Re-timing the bolt handle isn't a bad idea, but it will probably result in a "click" at the top as it removes the stuck brass. Running the brass once through a small base die will most likely solve your problem and make it function as it did previously

 

[JMGlasgow]

You haven’t told us if you’re using the same load data from your old barrel or not?

New load work up

 

[JMGlasgow]

The chamber the brass was previously fired in was probably a hair larger at the base than the new one, and now the web has a "memory" in the area that your resize die can't quite remove. When it's fired in the new chamber, it try's to spring back to the old diameter and sticks slightly. Re-timing the bolt handle isn't a bad idea, but it will probably result in a "click" at the top as it removes the stuck brass. Running the brass once through a small base die will most likely solve your problem and make it function as it did previously

I'll get a small base die ordered.

 

[XLR308]

This isn't a nitride treated CMV barrel by chance is it ?

 

[JMGlasgow]

This isn't a nitride treated CMV barrel by chance is it ?

No, just standard chromoly

 

[ShtrRdy]

If you fire factory loaded ammo in it does it have trouble?

 

[JMGlasgow]

I just fired factory American Gunner and no issues at all. Also, not every Alpha brass case is difficult to extract.

 

[jd5521]

I just fired factory American Gunner and no issues at all. Also, not every Alpha brass case is difficult to extract.

Good news I’d say! Small base for you order should fix your problem the. With the other brass.

 

[Unknown]

I would measure virgin brass, re-sized and reloaded brass, and fired brass to get comparisons. When I switched to small base dies for a 308 gas gun, the issues I had with cases sticking in the chamber disappeared. The difference in the base of the cases after sizing was only about 2 thousandths, but it was enough to completely eliminate cases sticking in the chamber, even with cases that had been reloaded a number of times.

When the cases would stick, the extractor would rip right through the case's rim tearing a chunk off the rim. That is one hell of an extractor, and it sure as hell had a good grip on the rim of the case. The problem was that the chamber had just a wee bit better grip on the case than the extractor had on the rim.. If I dropped a 12" piece of bronze brazing rod down the muzzle the stuck cases would pop right out.

 

[Qtip]

It is not the first time that I hear of this problem with Alpha brass. Try a lighter load.

 

[carlsbad]

Your load is not mild. If you're cratering primers and reading the other symptoms you describe, your load is "strong". Your stock remington bolts don't have much if any primary extraction. Conventional fix is to reloacate the bolt handle; I prefer to install a new PTG bolt if you're going do do the work and take on the expense. Of course that will change your headspace so best to do when you chamber up a new barrel.

If you have the bolt worked on, have the firing pin bushed. It will cure cratering and if you don't fix it, it will eventually be a problem.

If you keep tapping the bolt handle back with a hammer, you will eventually have to have it reattached. If you do have it moved or reattached, the Holland or PTG replacement handles are inexpensive and have a better extraction ramp--nice upgrade.

--Jerry

 

[JMGlasgow]

It isn't the brass. Hornady brass that was fired from my last barrel does the same thing. Not as often, but often enough that it's a problem. And the loads aren't hot, my Remington craters every primer it has struck regardless of if it's factory ammo or reloads, same cratering. It also doesn't matter what the powder charge is, most of the brass has stuck. No heavy bolt lift, and no ejector swipes. My M700 308 factory barreled action does the same thing as far as cratering.

Also, as far as I'm concerned, PTG can close their doors permanently.

I'll send this rifle to LRI eventually for a Tig and Time and possibly have the firing pin bushed.

I have a small base die coming tomorrow, I'll report back after trying that.

 

[carlsbad]

I did mention the Holland bolt handle as an option, since you're in the population that has given up on PTG. I've been there, but don't have another source for good bolts.

 

[JMGlasgow]

Is there something wrong with the factory bolt that requires replacement? I also should mention this is a left handed rifle.

 

[carlsbad]

Factory bolts are OK. They aren't great. They are mass produced. They aren't always straight They vary in diameter as does the boltway. i am a Remington fan, not a basher, but they are mass produced. I've built many 1/4MOA rifles with stock Remington bolts. but by upgrading I can make a Remington the equivalent of most customs. I ream the boltways oversize and put in a .705 bolt and have a fit just like a custom. If you're going to spend a lot of money on your bolt, for example I get a lot of requests to put a sako or M-16 extractor in, I recommend considering just going to the upgrade. That is my take on the bolt body.

As for the bolt handle, for some reason Remington doesn't put as robust an extraction ramp on the bolt handle as the aftermarkets. If you prefer the Remington handle, a good smith and reloate it and make it work. There isn't a lot of difference. Changing the bolt handle gets you a slightly longer handle which is advantageous for target shooting. The Remington 700 handle was developed for a hunting rifle so it was as short as possible to avoid getting hung up on brush.

Just my 2c. --Jerry

 

[JMGlasgow]

Shot the rifle today and yesterday after sizing all my brass with the S/B die. No extraction issues whatsoever.