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  1. #1
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    Default Remington 7400 problems

    I have my friends Remington 7400 SemiAuto rifle cal.30.06 trying to figure out the problem. With the clip in, pulling the bolt back and letting it go, it cycles the first round with no problem. After firing it the bolt does not come back and eject the fired round and pick up a fresh round. It appears the bolt did not move at all. I can manually work the bolt which will eject the fired round and pick up and chamber a fresh round. This can be done with no problem. The same thing happens after firing the second round and a third round. Manual operation is no problem. I cleaned the rifle pretty good before test firing. I am shooting new Federal 165 gr. ammo. The only thing I did not clean is the gas port in the barrel. Could not get to it. I did insert a pipe straw in the gas tube and shot carburator cleaner through it. I feel the problem is a gas problem. What do you all think? Help. Thanks
    mauserdad
    John 3:16 & 17 KJAV 1611
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  2. #2
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    Default

    Stuck gas piston.

  3. #3
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    Nailed it.
    Dave

    In 100 years who of us will care?
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  4. #4
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    Default

    If I am not mistaken the 7400 like the 742 does not have a gas piston, direct gas blowback via small gas tube at back of lug under barrel .The [gas tube] you saw is just a recoil spring guide tube.With forend off bolt locked back try shooting carb cleaner and or compressed air through that tube into barrel, if that is clear then More than likely has rust in chamber these are notorious for that problem, just like putting the brakes on when you fire a round, if rust is present you must polish the chamber to fix. Good luck !!

  5. #5
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    Thanks gents. Under the gas port on the barrel is the gas block. I found that there is a little allen screw on the bottom of the block. I removed it and saw a shiny object inside the gas block. After shooting some PB blaster and tapping on the block ,a little ball bearing came out. It had some corrosion on it. I cleaned it up and the gas tube coming out of the gas block. I was also able to clean the inside of the gas block and the port going to the barrel. I hope this will fix the problem. Will get back.
    mauserdad
    John 3:16 & 17 KJAV 1611
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  6. #6
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    Clyde is offline Gold Bullet Member and Noted Curmudgeon
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    Been beat to it, but when a gasser doesn't function at all, either the piston is stuck or the gas port blocked. Saw that happen (not often, but happened) with M-14s back when i was an Ordnance weenie and in and out of small arms shops.
    Last edited by Clyde; 06-21-2012 at 02:15 PM.
    Absent comrades (sound of breaking glass)

  7. #7
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    Default

    Well,I cleaned up the gas ports and tried polishing the little ball bearing. Fired three rounds. Each time the bolt came back about 3/4 of the way with the extracted round and stopped. Had to manually pull the bolt all the way back to eject the fired round,pick up the new round and to chamber it. I am wondering if the slightly corroded ball bearing is part of the problem.It is not really corroded but is discolored. I also am wondering if the allen screw that holds the ball bearing in place needs to be seated at a certain spot to let the ball bearing move completly free. Currently I have the allen screw snugged down. I see that the allen screw was peened in place at one time but I did not get it that way. I also took a drill bit the same size as the port hole in the barrel and manually moved it around in the port to try to remove any carbon. Any other ideas on what I might do? Thanks
    mauserdad
    John 3:16 & 17 KJAV 1611
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  8. #8
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    I'd guess you need to pull the action tube, spring, orifice ball and screw, and action bar assembly and clean them carefully. If not it may be the ammo, partly. The recoil spring fix, below, makes up for ammo with the wrong pressure curve, but may also batter the receiver.

    http://forum.gon.com/showthread.php?t=442950

    http://www.go2gbo.com/forums/index.p...,124187.0.html

    The manual and parts diagram is at http://stevespages.com/pdf/remington_7400.pdf


    BTW the 760 series pumps are a LOT more reliable and more than fast enough shooting. After reading the complaints about the older 740 series rifles my son bought a 760. He's a lefty and has problems with most bolt actions
    I swear by Jupiter Optimus Maximus .... in the army of the consul Lucius Quinctius Cincinnatus and for 10 miles around it I will not steal anything worth more than a sestertius in any one day.

  9. #9
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    Thanks for jumping in. I was hoping you would. The more I read about these rifles I wonder why Remington allowed this design. Boy what a problem child. Tonight I am going to try cleaning the chamber again. Another thought is to leave out the ball bearing and see what happens. I am doing this to see if the ball bearing was in some way restricting the gas. Another thought is to use good quality US Military ammo and see how it functions. What do you all think? Thanks
    mauserdad
    John 3:16 & 17 KJAV 1611
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  10. #10
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    Well,I did what I said I was going to do in my above post. NO GOOD. Still have the problem. Put the ball bearing back in. No effect. I have run out of ideas. Any more ideas out there? Thanks
    mauserdad
    John 3:16 & 17 KJAV 1611
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  11. #11
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    hand loads or factory?
    if it aint broke, fix it till it finally is.

  12. #12
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    Pull the trigger/firing group, clean and oil all the springs and pivots.

    All the stuff the bolt re-cocks/re-sets in recoil cycling is a part of the energy/drag equasion to cycling an autoloader, as is ANY OTHER parts that move when cycling.

    Did some internet research on this model, yes, no piston like my BAR.

    Corrosion is a known problem with these and causes cycling troubles.

  13. #13
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    Quotes from other forums on this topic:

    The biggest problem I have seen with the 7400's is that gunck gets into the trigger group and will gum up the works.
    We are constantly getting all three models in our shop for cycling problems. Some of them are because of not cleaning or "cleaning" with too much oil. Some are because the locking lugs have beat up the frame rails, some are because of the bolt head wearing out and not unlocking from the lug seats, Some are from parts breaking, etc... etc...
    I hunted with one for the first 10 years or so I hunted. The key is cleanliness. Keep em clean and they wont let you down.
    First thing to do is give the rifle a good cleaning. Remove the fore-end assembly to check for crud and rust. Clean the action spring and make sure the action tube isn't fouled. Fouling in here will reduce the travel of the action.
    Also, those rifles are prone to fouling. Make sure the the inside of the reciever is clean, including the are where the bolt locks up. Pay close attention to the bolt when cleaning. As stated, the gas system is very simple to disassemble and clean. Heres a schematic http://www.brownells.com/.aspx/sid=1...sdetail/7400_4 also, they need to be lubed properly to function.

  14. #14
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    Gents I appreciate the comebacks. As I have stated above I have stripped the rifle down 2 times and given her a very thorough cleaning. After each cleaning I have sprayed her down with a lubricant and used a air compressor to blow off the extra. I will strip the rifle down again and clean it. Maybe this time I will use oil instead of a spray lubricant. Will keep you all posted. Thanks
    mauserdad
    John 3:16 & 17 KJAV 1611
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  15. #15
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    The ball is just used to seal the hole in the gas block. The set screw should be tight to keep the gas going where it should.

  16. #16
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    3 biggest problems with 742 7400 Remingtons...dirt,, {lack or maint.} worn locking lugs on the bolt and barrel, and handloads.
    if it aint broke, fix it till it finally is.

  17. #17
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    Quote Originally Posted by chuckindenver View Post
    3 biggest problems with 742 7400 Remingtons...dirt,, {lack or maint.} worn locking lugs on the bolt and barrel, and handloads.
    You most certainly need enough muscle in the load to cycle the weapon. Lower-part-of-the-range just won't do it.

    After learning this, all load development for my BAR starts about mid-range in the data. An accurate load is useless to me if it fails to function the gun's action every time.

    If that ball is in any way "damaged" (corrosion pitted, dented, not smooth) I would replace it. If the seat it rests against is pitted, it could leak pressure, also not good.

  18. #18
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    Yes I am thinking of repacing the ball and seat if the problem persist. The funny thing is that I can manually operate the bolt to cycle a fresh round,eject and reload with no dificulty other than the normal recoil spring tension. Except for the one military round all ammo used to test has been factory Federal 165 Gr.. Will test fire again tomorrow after the third cleaning. Thanks
    mauserdad
    John 3:16 & 17 KJAV 1611
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  19. #19
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    if your using Greek HXP surplus. it is longer then a standard 30-06, and was made for the M1 Garand.
    try just some plain ol factory 150Grn Remington stuff, see if that works.
    if it aint broke, fix it till it finally is.

  20. #20
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    The Military round was U.S.. Will see if I have any Remington ammo.. Ordered the ball bearing and screw today from Remington. Should be here in 7 days. Thanks
    mauserdad
    John 3:16 & 17 KJAV 1611
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  21. #21
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    Your rifle is probably "worn out"; the locking lugs in the receiver wear and set back. No way to fix them.

    The 742 and similar 7400 are not designs that stand up to lots of use; just my opinion from having to deal with them for 40 years. When they are worn out and won't cycle, just hang them on the wall. Remington won't work on them anymore.
    03man - Don Voigt
    Author of "The Japanese T99 Arisaka Rifle" 2010 edition
    Co-author of "The Knee Mortars of Japan 1921-1945" 2011 edition
    Near Charlotte, NC

  22. #22
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    Thank you. I am coming to that conclusion. Will try with the new parts and that will be the end of my envolvment. Thanks
    mauserdad
    John 3:16 & 17 KJAV 1611
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  23. #23
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    i used to work for a Remington Repair center...80% of these rifles that came in were scraped, unsafe. mostly from heavy handloads...
    the 760 and 742 should only be shot with factory ammo, not surplus or handloads...FYI: Remington will give you credit for the rifle,,but not if its had handloads or surplus ammo shot through it. not sure how they would know...unless you tell them so.
    in the 1990,s they used to give 250.00 credit towards a 700 ..not sure if that program is still in effect.
    if it aint broke, fix it till it finally is.

  24. #24
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    Thank you for the credit info. I will let my friend know that.
    mauserdad
    John 3:16 & 17 KJAV 1611
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