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Thread: Excess Headspace
01-26-2009, 02:49 PM #1
Hello fellows. I lurk here often and learn lots. I have a question regarding headspace on a 338 win mag in a T/c Pro Hunter. I understand that because of the action design they will not be built very tight. However, I recently purchased the 338 barrel for my prohunter in stainless, installed it etc. I had it out for a few test fires yesterday. Upons returning home I inspected the cases as normal for loading and much to my amazement 4 out of five are cracking above the web of the case.
I then removed the barrel and inserted a new unfired brass in the chamber. The case head sits about .009-.010" below the breech face of the barrel. I thought hmm for a single shot this should be flush. I then took two of the fired cases pressed them in the chamber one at a time firmly, measured how much they protruded. They protrude about .009-.010" from the breech face of the barrel. Even if the barrel closed up flush to the rear of the action I would still have a .010" case stretch. Right now it is stretching the cases .018-.020" way too much. Any one else come across this.
I would assume returning the barrel is the next step????
01-26-2009, 03:41 PM #2
Sounds to me like the chamber was cut too long... can you return it? I would if you can.
01-26-2009, 05:51 PM #3
belted magnums are finicky about headspace. since the belted magnums headspace on the belt for the first firing, if the distance from the belt to the shoulder is long you will get separation in front of the belt. i was having this problem even with a tight chamber and federal brass. i switch to winchester and it went away. i am on my 7th loading with out any thinning of the case wall in front of the belt.
if the case is growing .018"-.02" by measuring at the breech, i think there is a definite problem with the headspace.
01-26-2009, 06:26 PM #4
Thanks for the replies guys. I figured that the magnums head spaced on the belt. I wish I had a set of go, no-go guages here as well as a field guage. I would bet that thing would close down on the field guage.
I am going to cabelas where i purchased the barrel this saturday. I will take my depth micrometer and some new brass with me to measure and prove out to them the problem.
01-26-2009, 10:56 PM #5
Did they have your receiver when chambering the barrel? If not, how did they or you measure the headspace?
01-26-2009, 11:28 PM #6
If they won't take the barrel back, and you handload your ammo, I can tell you how to get around this problem. I just had the same type of problem...but with .032" headspace. It took three firings to crack mine ahead of the web though. I now can get at least 12 firings without a problem, I just kept reloading and shooting one piece of brass and stopped at 12 firings with no signs of any problems.
01-27-2009, 07:44 PM #7
It sounds like a problem that should be fixed. However, if you forget about using the belt to control headspace and size the brass such that the shoulder controls the headspace, you should get good case life.
01-27-2009, 07:57 PM #8
My understanding is that the barrels for the pro hunter encores are done in a jig or some set up that apparently makes them the same fit in all the actions.
First off, if i drop an unfired round in the barrel the case head is .010" below flush with the breech face of the barrel. All single shots I have been around it is dead flush. Put a fired case in the barrel and seat it firmly it sticks out about .009- .010". Now my understanding is that the breech end of the barrel in a break open cannot lock right up tight to the face of the action.
Jeff I understand how to load for excess headspace, by not full length sizing the case etc. The problem is a brand new case fired once in this thing is already showing crack lines just above the web.
I will return the barrel on thursday night. Take unfired brass with me along with my depth mic. If an unfired brass will sit flush I wil accept it in exchange. If it is deep like this barrel I will then get a refund and find a custom barrel for it.
Butch you advised me on a rebarrel of a browning BBR a couple years back. I got around to that project. Put a new take off Remington barrel that I obtained for free on to that action.
Worked out great. Thanks.
01-27-2009, 08:27 PM #9
ya might want to take a cracked case also so that even a sales clerk can see theproblem
01-27-2009, 10:01 PM #10
Yes triggerman you are correct. I will take the cracked cases with me as well. Probably will make them nervous seeing me put some brass into the barrel.
01-27-2009, 11:38 PM #11
Sounds like you are on the right track Charlie. Let us know what happens.
01-28-2009, 11:42 PM #12
I've never had an encore apart. Does the pivot pin have to come out to replace the barrel, or is it like a NEF/H&R. I just wonder if someone at thompson got a pin that hadn't been hardened in a rcvr, and you just happened to be the lucky buyer. Not knowing what you had it barreled for, I would suggest you check the pivot fit, might not help to change the barrel if the pin's worn/dented. Seems like .010 is a lotta space between the barrel and frame. I know I can't see light between the barrel and frame of my contender, but I can't shoot magnums in it either.
01-30-2009, 12:03 AM #13
Lazurus, The pin does have to come out on the encores to change the barrel. The pin on this gun is in perfect condition. I have mic'd it a few times already. Muzzle loader barrel fits well. The issue with this particular barrel is not the space between the barrel and action. That is around I think .004"->005" as near as I can tell. The issue is if new brass is put into the chamber it sits down into the chamber .010". Too deep.
Butch, I took the barrel into the supplier tonight. Luckily there was a guy at the counter who had shooting and loading experience. I gave him a brief explanation of the problem and then handed him one of the fired cartridges. He looked it over and said you are right, this is unacceptable. He calls to the back and has another barrel brought out from the wharehouse. We unpacked it, same problem. Then he calls the manager over and we start to show him the issue. I could tell immediately he was not a shooter / loader type. The gentleman behind the counter basically told him if it were his barrel he would not be happy with it either.
I told the manager at that point that I thought a straight return was my best option. Dealing with the local factory rep etc. could lead on and on. So they gave me a refund.
Now I have to decide which custom barrel maker to call.
01-31-2009, 04:53 PM #14
OK thinking on this.
How do we know it is the barrel and not the ammo ??
I know a guy who shoots for TC (Chad Cleland) TC took him and a group of gun writers on a trip up to Canada to hunt, they were getting misfires in Contender carbines using a factory bottle neck case. Turns out the ammo itself was to blame not the rifles, the cartridges were too short headspace wise.
TC has excellent customer service, if you had called them directly they might have given you an answer.
01-31-2009, 06:30 PM #15
The headspace gauge for the H&H magnums is just a gauge for the belt.So you have to wonder how we get any proper chambers.
01-31-2009, 07:59 PM #16
Hi Willbird, I hear you on the ammo concerns. However I did do a test fit with two different brands of brass, both unfired. Win, and Remington. Both sitting low in the chamber. Could there be a reason T/C sets them up this way, maybe??
Like Downwind tracker says the magnums head space on the belt. This particular barrel the brass sat down in the chamber ten thou. If and I say if this were a bolt action gun that would be too deep as well would it not?
On the thought of contacting T/C directly, well that would be an option. However shipping a barrel back and forth across the border between U.S. and Canada can have its own issues as well. I really didnt wish to get involved a several month dealing over this. I still like the rifle itself. As a muzzleloader it shoots excellent.
I thought had crossed my mind to get a 338 federal barrel, then ream to 338-06. This way I can ream until the chamber is dead flush with the breech end of the barrel and thus end up with in say .004 of the breech face.
I have two other single shots in my collection. A b-78 browning in 30-06 and a sharps 45-120 in a Shiloh. Both those guns the cases are flush at the end of the barrel. Both shoot well and case life is excellent. If I have a rifle that is going to present some case life issues I wont keep it as I like to load for all my rifles.
So I did get credit for the barrel and it really wasn't a big deal. No harm done.
Now I just have to decide what to put on for a centerfire barrel. I do like the 338 calibre idea. The 338 federal maybe being a little light for what I want. That is why the 338-06 is in my mind. Hmmm???
01-31-2009, 08:58 PM #17
Well to be fair to the mfg, only checking with a headspace gauge would reveal if the barrels were chambered to Saami specs, if they were it is no fault of the mfg.
02-01-2009, 02:10 AM #18
I have one and 338WM. For a single shot,recoil would be more of a question,than thump.In the last few years, we now have powders that are 2gr faster than 4350 and 4gr slower than 4064. This is perfect for filling the 06 case when using .338 225s. The 2650 of the 338-06 and the 2800 of 338WM are close enought to the drop of 180 30-06,you can use those tables.
02-01-2009, 11:15 AM #19
Common Problem with Mag cases
1. Have the correct gage to check the TC barrel. Go- .220, No go- .223
2. Have someone with the mag chamber reamer make up a shell case gage
Make a gage out of 1" dia by 3/4" long block of steel. Ream depth to about .230 for checking the brass case with depth mic when dropped into the gage. Use the headspace gage of .220 to mark the gage for the tolerance so you can mic all cases to see the difference of the belt thickness down into the gage. You will find that brass will very from brand to brand and lot to lot. Weatherby and Norma headspace was set with a min. gage of .217 as the go gage. I worked warranty on most factory guns and when a gun came in with the problem mentioned in these posts the first thing was to check the brass. I found miss fires caused with some mag. cases had as much as .012 under dimensions on brass which caused all kind of problems with case head splits and miss firing.
If this proves to be the problem I would send it back to TC for their check.
02-01-2009, 12:32 PM #20
Downwind, I have been researching the 338-06 for quite a while. I have found one must obtain a custom barrel or a barrel from T/C custom shop to get the calibre. A good friend of mine has a 338 federal barrel he is not using and I can buy this for the right price. I thought at first one could ream the 338 federal chamber ot 338-06 but I have since learned that this is not possible because of some case size and taper issues.
I wonder how much trouble it is to have the chamber redone to 338 win mag.
Insofar as recoil difference between the 06 and the magnum goes that wont be too much of a problem. I have shot 375 H&h quite a bit and it is much worse.
Interesting thing when I was looking at that 338 federal barrel the rifling has a left hand twist as compared to the right that I see most of.
Anyone ever rechmber the 338 federal to a 338 mag?