Chamber throat questions

[ssgw]

wrench

I'd recommend against using an internal wrench on a stubborn or factory installed 700 barrel.

I have a hunch the lug is just rough because its a new production Remington and not because of a hot load. I also have a hunch the case head separation is over resized brass, and not a problem with the rifle at all.

If you're going to replace the "action", are you planning on reusing the barrel? Realistically, by the time you refit the barrel to the new action, you may as well just completely start from scratch with a new action and new barrel.

What are your thoughts against using the internal wrench?

As for the hot load..maybe so. I may never know the whole history. From borescoping the throat, it looks like a few rounds have gone down the tube. The owner provided me with his dies, powder, primers, bullets, all that he used to make the rounds with, as well as new brass. He had the same problem, old and new.

If I changed the action, I was going to reuse the barrel, that is if I can find a definite fault in the action. There just has to be an reason for the issue he is seeing, and I am determined to at least find it, if not fix it.

 

[Sea Sick Steve]

I agree.
It turns out that it did not start happening until he used reloads with a change in powder. It sounds like maybe he put a real hot round through it and damaged the lugs.
I have a Remington internal action wrench due in the next day or two to get his off along with some heat. I don't want him to think that I broke the lugs either.
My suggestion to him if my suspicions are correct, that I can replace the action for him with a Holland or PTG 700 clone. I want to be able to save face for him..it just may cost as he's aware of.
I will post more when I get the thing fully apart.

As others have suggested it sounds like the shoulder is being pushed back too far during the case sizing operation. The powder change may be a red herring could be as simple as the brass being overworked and the web becoming thinner on subsequent firings. Perhaps the RL19 loads were fired 1x cases and the Retumbo loads were 2x fired cases, every time you push the shoulder back and fire again the web will get thinner. If any of the cases actually fractured at the web upon firing it would allow the brass and powder residue to get into the bolt lug recess area which you have seen with the borescope. I cant explain away the broken/ rough area you see on the integral lug, this is a problem. Is it possible you are seeing the closing cam on the edges of the integral lugs they can be pretty rough finish. Just some ideas

 

[Sea Sick Steve]

Any other suggestions for a replacement action that should fit his same stock? He has a lot of money in that alone.

Bugholes.com
He shows stock on Stiller tac 338 action and has Brux 338 9.5 twist barrels in stock as well The tac 338 uses a 1.125"x 16tpi thread your Remmy bbl is going to be too small

 

[300sniper]

What are your thoughts against using the internal wrench?

As for the hot load..maybe so. I may never know the whole history. From borescoping the throat, it looks like a few rounds have gone down the tube. The owner provided me with his dies, powder, primers, bullets, all that he used to make the rounds with, as well as new brass. He had the same problem, old and new.

If I changed the action, I was going to reuse the barrel, that is if I can find a definite fault in the action. There just has to be an reason for the issue he is seeing, and I am determined to at least find it, if not fix it.

Internal wrenches are risky on breaking loose a factory or over other stubborn barrel (sounds like this one is either or both).

His reloading equipment isn't going to help you. You need to know what his resized brass measures to the shoulder vs. fired brass. If there's more than about .002", there's your problem. I've certainly been wrong before and could be here, but my gut says there's absolutely nothing wrong with this rifle and he is simply over sizing his brass. If I were a betting man, I'd put money on it.

 

[ssgw]

internal wrench

Internal wrenches are risky on breaking loose a factory or over other stubborn barrel (sounds like this one is either or both).

His reloading equipment isn't going to help you. You need to know what his resized brass measures to the shoulder vs. fired brass. If there's more than about .002", there's your problem. I've certainly been wrong before and could be here, but my gut says there's absolutely nothing wrong with this rifle and he is simply over sizing his brass. If I were a betting man, I'd put money on it.

Why do you think that the internal wrenches are risky? I am thinking that you'll get a better purchase when putting torque on the barrel.

I am with you on the brass sizing. I have repeated my question to the owner if he is having the same problem using new brass. If I don't see anything definite, I will load some new brass myself and try it. Any tried and true light 338LM loads out there? My only question then with the brass is why don't I see any change in neck length on his cracked rounds? They are all within normal spec's.

 

[paracongo308]

Why do you think that the internal wrenches are risky? I am thinking that you'll get a better purchase when putting torque on the barrel.

I am with you on the brass sizing. I have repeated my question to the owner if he is having the same problem using new brass. If I don't see anything definite, I will load some new brass myself and try it. Any tried and true light 338LM loads out there? My only question then with the brass is why don't I see any change in neck length on his cracked rounds? They are all within normal spec's.

I guess I have to show photos of why its risky to use internal wrench's, on factory installed Remington barrels. You also risk distorting the receiver using one other then for a switch barrel setup.

 

[GGaskill]

You will be applying a greater force for the same torque since it is applied closer to the centerline. Also, there is a potential for twisting both wrench and receiver because of the great length of the internal wrench.

 

[ssgw]

I was really frustrated trying to get this barrel off. I finally did after heating it up to 500F a couple of times and allowing it to cool each time. I had 200ft/lbs on it when hot and it didn't budge. The last heating, I let it cool over night and it broke free with 40ft/lbs.
Well one thing that I found when I got the barrel off was this....The barrel tenon has normal threading which should end with an undercut relief cut. This has threads and bout 3/16" area of no threads and finishes with 2 mm relief cut that serves no purpose after that big gap. I am wondering with no functional relief cut, can the threads not be fitting well enough to give that temporary movement ending in my headspace problem?
I am really interested to hear what you think.

 

[paracongo308]

Can you post a photo of the tenon?

 

[ssgw]

I can tomorrow when I get back there. Thanks

 

[300sniper]

Can you post a photo of the tenon?

Please do.

 

[300sniper]

I was really frustrated trying to get this barrel off. I finally did after heating it up to 500F a couple of times and allowing it to cool each time. I had 200ft/lbs on it when hot and it didn't budge. The last heating, I let it cool over night and it broke free with 40ft/lbs.
Well one thing that I found when I got the barrel off was this....The barrel tenon has normal threading which should end with an undercut relief cut. This has threads and bout 3/16" area of no threads and finishes with 2 mm relief cut that serves no purpose after that big gap. I am wondering with no functional relief cut, can the threads not be fitting well enough to give that temporary movement ending in my headspace problem?
I am really interested to hear what you think.

I am suspecting there is no thread relief because it is not needed. I am also suspecting the undercut being referred to is an undercut to get the radius left from the tool below the tenon/shoulder transition so the recoil lug can fit flush against the shoulder.

This is absolutely none of my business so feel free to tell me to FO, but are you being paid for your time on this project?

 

[paracongo308]

Another size you might want to post is the thickness of the recoil lug. What you described about that tenon doesn't sound like it left Remington that way.

 

[ssgw]

Looking at it again, yes the 2mm is a radius undercut to allow the recoil lug to fit flush with the barrel. The gap that I spoke of ....dahhhh...is the space that the recoil lug sit on. Still there is no thread relief. Is that necessary? All the schooling and books that I've had on it say yes...but I cannot remember why.

 

[300sniper]

Looking at it again, yes the 2mm is a radius undercut to allow the recoil lug to fit flush with the barrel. The gap that I spoke of ....dahhhh...is the space that the recoil lug sit on. Still there is no thread relief. Is that necessary? All the schooling and books that I've had on it say yes...but I cannot remember why.

It is not necessary in this situation.

 

[paracongo308]

Looking at it again, yes the 2mm is a radius undercut to allow the recoil lug to fit flush with the barrel. The gap that I spoke of ....dahhhh...is the space that the recoil lug sit on. Still there is no thread relief. Is that necessary? All the schooling and books that I've had on it say yes...but I cannot remember why.

You don't need thread relief providing the thread is long enough on the tenon for barrel lockup against the recoil lug. When I thread a barrel I don't undercut as the thread is uninterrupted within 1/8" of the shoulder. The only part that I undercut is the shoulder a few thousandths deep to remove tool radius.

 

[ssgw]

That's not the problem then..........uuuugh!

 

[GenePoole]

You don't need thread relief providing the thread is long enough on the tenon for barrel lockup against the recoil lug. When I thread a barrel I don't undercut as the thread is uninterrupted within 1/8" of the shoulder. The only part that I undercut is the shoulder a few thousandths deep to remove tool radius.

Some pictures to illustrate this:

 

[300sniper]

That's not the problem then..........uuuugh!

What is the difference in length to the shoulder datum between a one time fired piece of brass and a piece of brass he has resized? If you can't answer that, you are spinning your wheels trying to fix a rifle that is almost certainly not broken.

I'm telling you, this is a reloading problem, not a rifle problem.

 

[wesg]

I'm with sniper on this. If he's measuring the cases at all at the sizing operation, or maybe just setting the die down on the shell holder like we all did 40 years ago.

A friend had an issue years ago, where cases sized according to the cartridge headspace gauge wouldn't go in the chamber until they were sized 8 or 9 thou under the dimension they were after firing. He gave me some cases to look at on a comparator. What I found was that the shoulder was bulging, which turned out to not be the issue ...

Speculation was the chamber gauge he was using didn't match the shoulder angle of the .308 case. So as the case body was being squeezed down the shoulder was moving forward and his gauge was picking that up in the wrong place. The dies were OK, and so were his cases once they were sized so the bolt would close. I made him a simple gauge with a 20° angle and the numbers all matched from that point.