7mm Mag Hard Extraction

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by 7stw, Mar 13, 2011.

  1. 7stw

    7stw Well-Known Member

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    I have a recently acquired 700 p in 7 mag. I set it up in tactical style, and took it to the range today with a load that has been a accurate load in several other sevens that I have owned. Now I know that every rifle has it's own likes and dislikes, but the rifle fired ok, but On extraction, the bolt would cam open to the top of it's stroke but needed a firm rap to the rear to get it to extract.I didn't shhot many rounds before I decided to investigate this a little further when I get home. The brass was previously fired in another rifle, but was FULL length resized. My thoughts are to reduce oal, and reduce charge bt 10 percent, and possibly start with new brass. May even try some factory stuff just to rule out my own processes. I am a meticulous loader and do not BELEIVE that I did anything wrong, but anything is possible! Anybody ran into this before? This rifle is a pre ProMark trigger model. gun was/ is in immaculate condition, actually believed to be unfired when purchased. Any thoughts.? AIM SMALL! MISS SMALL,
     
  2. Edd

    Edd Well-Known Member

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    I've ran into it every time I have tried to share loads among 7mm Remington Mags. I had three of them and they each liked a different load. The load I shoot in the one I have now is too hot for any other 7 mag I've seen.
     

  3. 7stw

    7stw Well-Known Member

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    Thanks for the feedback and the vote of confidence in my own analogy of the source of my problem. I think it is exactly that, but it is going to drive me nuts til I get to go to the range again. I have been working SO much recently and finally got a day off to smell some burnt nitro, and this is what I got for being so anxious to be able to shoot that I failed to back off a little on the starting load. but that is all that I can think of that would cause that. No other pressure signs were noticed though! Anybody else have any thoughts?
     
  4. AZShooter

    AZShooter Well-Known Member

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    If you can easily lift the bolt but have difficulty moving it rearward you may have an area where the chamber wall is a bit larger allowing the brass to expand into it. Check your cases and see if there is a shiny area on the body. It could be full circumference or just one place. A full circumference shiny spot just in front of the belt would indicate that the rifle was fired with a super high pressure load which bulged the barrel.


    Let us know what you discover.
     
  5. shortgrass

    shortgrass Well-Known Member

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    Is the extraction cam on the bolt handle engaging the extraction cam on the receiver?
     
  6. 7stw

    7stw Well-Known Member

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    Well, after reading some of your replies, it really has me thinking that this rifle may either be going to a smith, or to Big Green. In all honesty, the brass does not have any abnormal looks about it, but then again I have not puT a mic on it either. I will
    Do a little experiment this weekend, and if I don't get better results, I will do one of the aforementioned . The brass I fired was fired several times, but was full length resized and trimmed. That load MAY have been warm for THAT rifle. I think I will try some factory stuff first. IF that works, I will rework the load and start with fresh new brass. This one is a first for me and hopefully the last. I will keep you posted.
     
  7. 7stw

    7stw Well-Known Member

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    You hit it right on the head, pardon the pun. On a few visits to the range since that first outing, I tried some Hornady superformance 162 SST. They fired OK, and with authority I might add, and they extracted with just a little resistance. After I got home, I noticed on all of the brass, right ahead of the belt there are what appears to be machine marks that look like record grooves. I don't know if time will take this out, or can the chamber be polished out, or does this create other problems. I loaded some 168 Bergers, and 162 A-Max and fired them with about the same results, but they did extract. I was told that I might be able to polish it out using a shotgun swab and either super fine lapping, or JB bore cleaner. Any thoughts? P/S, those 168 bergers shooooot!
     
  8. AZShooter

    AZShooter Well-Known Member

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    I am sorry to hear that your chamber has a expanded area in front of the belt. Did you buy it used or new? It might be a tough thing to convince Remington that their barrel came that way from the factory, if it is new. They will most likely blame you for shooting a hot load.

    If it is used consult a gunsmith. Can't imagine you can polish it out. It would require sanding and that would be difficult with the belted area besides it could make the chamber too large. Probably best to set it back enough to clean it up by rechambering. See what your gunsmith says.
     
  9. Topshot

    Topshot Well-Known Member

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    We got a bad batch of Remington 700's in 7mm Rem Mag early last year.
    I bought one and had to pull the barrel. We found a large bur right around the chamber just in front of the step for the case belt.

    I could not even fire factory loads with out having to bang the bolt open. The only way I could shoot it was with very light reduced loads.

    A number of other rifles had the same problem and were sent back to the shop from where I bought mine. You sound like you got one too. The chamber will need to be recut if it is like mine.

    I still have it in the shed having replaced it with a .338 barrel after only a hundred rounds or so.
     
  10. 7stw

    7stw Well-Known Member

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    What to do, what to do? That is the question. It did fire the factory superformance 162, and the extraction wasn't perfect, but I will always be wondering while I am shooting it IF it is going to eject. I did try calling Remington, but the lines were tied up, and the recording says call back later.Huuum! Go figure. I could rechamber to 7mm Ultra mag using this same barrel. I did consider rechamber to 7mm STW, but the affected portion of the chamber would not be changed at all. That portion is the same on both cartridges. Or, I could set it back a few threads and recut chamber, either way I am still looking at at least a rechamber. And I am almost afraid to send it to the factory nowadays. I have in the past with excellent results, but afraid to now. Maybe it's time to call up Dan Lilja......Frustrated. Really did want to shoot these 168 Berger VLD's. ( sooner than later) Well anyway, AIM SMALL, MISS SMALL, gun):rolleyes: ANY THOUGHTS?
     
  11. AZShooter

    AZShooter Well-Known Member

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    I would try calling Remington a few more times.

    Other options:

    You could look for a new 7mm Rem mag takeoff. They are out there. I looked for a new 243 takeoff just a week ago. I posted a WTB on a couple of sites. 6BR gave me five responses in one day. While I haven 't done it, I understand that the barrel might fit without any adjustments for headspace. If not then you will have to pay a bit for headspacing.

    On the other hand you would have put a new barrel on it eventually. Might as well do so now. If you want to shoot VLDs give yourself every advantage and buy a reamer with the throat positioned so those long VLDs fit the magazine. Pacific Tool and Gauge made my 7 Rem Mag reamer which has a 1 degree 30 minute angle in the throat. This seems to be the best angle for shooting VLDs as it also worked well in my 257 weatherby and my friend's 22-250, 284 win and 30 AI.

    let us know what happens.
     
  12. 7stw

    7stw Well-Known Member

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    Well guys, I did call big Green, and they told methat i was looking at a 6to 8 week week at minimum. So i contacted my local guy whom I have the utmost faith in and he told me that he has seen this before and strongly beleives it to be a burr in the chamber and that he feels he can polish it out without damaging chamber. We examined the brass and you could clearly see roughness right ahead of the belt all the way around the brass. it was not deep, but upon firing, it "grips" the brass and won't let go with normal extraction assist with the bolt. Down time is less then a week, and for $60.00 , I consider myself lucky. It could be worse, but if this does not work, it is probably going to become a 7mm Ultra-mag. Or I may just re-barrel it with the help of Dan Lilja. I am confident that this will fix the problem. If not, we will see. AIM SMALL, MISS SMALL....7STWgun)lightbulb