Excessive case expansion question

[Hunt5BN]

I hope someone can help me with this. I had a local gunsmith cut, chamber and install a Krieger barrel on my rifle. The rifle is a Remington 700 in .308 Win. I have been reloading for the rifle and getting some great results as far as accuracy, SD and ES. The problem I have is that after reloading the brass 2-3 times I am experiencing case head separation .

I am using new Lapua brass and Redding full length competition neck size dies. I am using load data from the latest Hornady manual. The latest case failure was Lapua brass with a 155 grain ELD match bullet and 40 grains of Varget with a federal GMM primer. The brass had been reload twice previously. The Hornady manual lists the starting charge weight at 35.9 grains and max charge at 44.9.

I have my resizing die set to bump the shoulder back 0.001.

What I have noticed is that the case web expansion is pretty extreme on my fired brass. The SAAMI brass spec for the area just above the extractor cut is .4703. My fired brass measures .4740. when I have the die screwed in far enough to bump the shoulder it resizes the web to .4700. I tried to chamber this unloaded brass in my son's stock Remington 700 and it won't even let me close the bolt.

My questions are, can the rifle's chamber be recut (resulting in shorter barrel?), or can I just neck size the brass to avoid overworking the web area with full length resizing, or do I jest get a new barrel?
thanks in advance for any input!

 

[Bang4theBuck]

I'm having a little trouble following your post but I will say that it doesn't take much off of the barrel.to have it set back enough to correct the issue as I understand it. Depending on where exactly you are saying the case is stolen, it could be as little as .250"

Curious how much of the case sticks out the rear of the barrel when the case is all of the way into the chamber.

Can you take few reference photos and post them?

 

[MagnumManiac]

The only way to be certain is to rip the barrel off and take measurements.
It sounds to me that the chamber is oversized at the rear, it may even be eccentric.
You could do a chamber cast and measure off that.
Can you take some pics of fired brass and post them please, it will make it easier to determine the issue.
You may want to adjust your die so that the headspace measurements stays the same as a fired case. The body will be sized regardless and may not prevent further head separations unfortunately.

Cheers.

 

[26Reload]

I had 2 boxes of Lapua 65284 brass do the same......initial firing and 2 reloads and case head separations on almost every piece....distinctive lines on brass.....
At GS we did testing with new brass(unfired)....found that the specs were correct.....
Ended up pulling barrel and rechambering just so very shorter...
And all is well.....
I think Lapua put out some super soft brass.........

Have you tried any factory loaded to compare for headspace lines....

But definitely only neck size til third firing...and look for separation lines..
Or check with a pick inside the case after first & second firing....

 

[Seabeeken]

I agree, it sounds as though the chamber may be oversize at the rear. I had a 280AI barrel made and upon firing there was a .010 bulge on the case just forward of the web. It looked horrible. After a call to the barrel maker and giving him some measurements, and him trying to get me to overlook it, he had me return the barrel. I also sent fired brass. He called and said he would have to remake the barrel and that the "trainee" who did the chamber polish overpolished the rear of the chamber in addition to polishing crooked and took too much off one side of the chamber. I realize mistakes happen and was more upset that he tried to get me to keep it as it was. Ive not ordered a barrel from them since. You may be able to set the barrel back and recut the chamber with minimal barrel length lose. You smith will have to look at that.

 

[Mikecr]

I have my resizing die set to bump the shoulder back 0.001.
What I have noticed is that the case web expansion is pretty extreme on my fired brass. The SAAMI brass spec for the area just above the extractor cut is .4703. My fired brass measures .4740. when I have the die screwed in far enough to bump the shoulder it resizes the web to .4700. I tried to chamber this unloaded brass in my son's stock Remington 700 and it won't even let me close the bolt.

My questions are, can the rifle's chamber be recut (resulting in shorter barrel?), or can I just neck size the brass to avoid overworking the web area with full length resizing, or do I jest get a new barrel?
thanks in advance for any input!

When you bump back 0.001, is that from a point of actual zero headspace?
You shouldn't bump until fire formed to reach zero headspace, which you would bump from.

Forget SAAMI brass spec, it's not YOUR brass spec.
What does your new/unfired brass measure above extractor groove?
If that measure is growing so much as described, it is excessive chamber clearance. I would suggest to the point of being unsafe, as the web area is not gripping the chamber, allowing the brass to stretch back and cause high bolt thrust (as well as your case separations).

Yeah, you can set back the barrel maybe an inch and re-cut the chamber with a better reamer, and better gunsmith.
It should not cost a lot to have that done.

 

[milboltnut]

first things first buy no go headspace gauge and check it, or have the gunsmith gauge it. If a stripped bolt closes to far on a no go gauge then get your money back and find a better gunsmith, even if you have to ship it across the country.

 

[Reelamin]

Please post up your end discovery and results. Sounds like you have a serious head space problem or bad chamber. I have a factory A Bolt in 300wm that does not bulge and will start to separate at 3-4th firing. Mine shoots so good I have lived with it for 25 years. I would suggest the smith make it right and prove to you it was right. You should not have to put one penny more into it or have a shorter barrel.

 

[milboltnut]

 

[Prairie]

I ran into the same exact problem with a rifle that I bought. It was an Interarms Mark X in .270 Win. caliber. I noticed that when I went to resize the brass, I had to really crank on the press handle to get the case to resize. I looked at a case and saw that it was bulged just ahead of the web. Well I have other ..270's so I opted to get rid of the Interarms rifle. But that's the first time that I ever came across that problem until I saw the post here. I could have rebarreled the rifle but opted not to mess with it. I guess it was a machining problem from wherever the barrel came from.

 

[jarnold37]

I hope someone can help me with this. I had a local gunsmith cut, chamber and install a Krieger barrel on my rifle. The rifle is a Remington 700 in .308 Win. I have been reloading for the rifle and getting some great results as far as accuracy, SD and ES. The problem I have is that after reloading the brass 2-3 times I am experiencing case head separation .

I am using new Lapua brass and Redding full length competition neck size dies. I am using load data from the latest Hornady manual. The latest case failure was Lapua brass with a 155 grain ELD match bullet and 40 grains of Varget with a federal GMM primer. The brass had been reload twice previously. The Hornady manual lists the starting charge weight at 35.9 grains and max charge at 44.9.

I have my resizing die set to bump the shoulder back 0.001.

What I have noticed is that the case web expansion is pretty extreme on my fired brass. The SAAMI brass spec for the area just above the extractor cut is .4703. My fired brass measures .4740. when I have the die screwed in far enough to bump the shoulder it resizes the web to .4700. I tried to chamber this unloaded brass in my son's stock Remington 700 and it won't even let me close the bolt.

My questions are, can the rifle's chamber be recut (resulting in shorter barrel?), or can I just neck size the brass to avoid overworking the web area with full length resizing, or do I jest get a new barrel?
thanks in advance for any input!

When I first started fitting and chambering, I ended up with a chamber that expanded almost 7 thousands at the web. Bought a new bigger lathe soon after and learned that the tailstock was 2 and 7 tenths high. Most are made that way. The tailstock is not the gunsmiths friend. Even though it was aligned left and right, it was out almost 3 thousands high. Took to a machine shop and had it surface ground down to alignment. If a reamer is pushed in cutting a chamber, and the back end is 3 thousands high, it will produce a fat chamber. Magnum cartridges are even more troublesome as it allows the belt to swell to this oversize dimension and it can not be sized back down.

 

[Hunt5BN]

Thank you for all the replies and recommendations! I dropped the rifle off with a well known rifle maker yesterday. His initial thought without taking any measurements was that the when the chamber was cut the reamer that had some wobble which resulted in a loose chamber. He said he will measure everything and then likely have to cut a portion of the chamber off and re ream the chamber. I will let you know how it all turns out.
thanks again!

 

[QuietTexan]

I've been there with getting a chamber reset, it sucks to go through but it's usually the best answer in the end.

Hopefully he can save it, if not the first guy owes you a barrel IMO.