Rem 700 action limits

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Topshot, Feb 14, 2010.

  1. Topshot

    Topshot Well-Known Member

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    I have a Remington 700 action that is fitted with a 30" heavy Lilja barrel plus brake in .338 Edge.
    Now this rifle can handle up to 97 gn of H1000 no problem. It shoots the 92 gn load very well, but anything past 92 grains and accuracy starts to deteriorate.
    I have tried looking for nodes etc but it is no good. I am beginning to think that action flex under the higher loadings with the long heavy barrel is the problem.

    So what do you think? Are there limits to loading/barrel weight and length that effect the Remington 700 action?

    What would be a good custom action that would solve these problems?
     
  2. royinidaho

    royinidaho Writers Guild

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    I wouldn't think that the strength of the action, in and of itself, would be the problem.

    I had some loads in an Allen Mag cartridge in an a Rem 721 action with an improper type of powder. The powder bridged giving very very excessive pressures. I mean very excessive. Longer story short all three gave the same pressure signs, ruined cases, primer dislodging, and on and on. Still shot 1/2 MOA.

    Measuring of fit and finish may be in order.
     

  3. geargrinder

    geargrinder Well-Known Member

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    I don't think your action is the limiting factor. It could be just a quirk of the cartridge, powder, and bullet combination.

    Shawn says that his common load is 92-94g of H1000. Sounds like your right there.

    If you really need to push it to the limit, you might need to try a different powder.
     
  4. remingtonman_25_06

    remingtonman_25_06 Well-Known Member

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    97g of H1000 under a 300g SMK sounds a wee bit on the warm side, probly why your groups aren't very good.

    Dont have QL handy at the moment, but I think around 91g is at its max pressure limit.

    97g is going to put you waaaaaaaay over the 70K mark...

    My new lot of H1000 in my 338 EDGE w/28" HART barrel, I had to back down to 89g from the standard 92g when I first developed the load. I was piercing primers with the new lot with 92g, velocity was 2900-2950fps and groups were around 1 MOA. I knew something was up...Backed off to 89g where velocity was back down to 2825-2850fps and groups were back down to 1/2 MOA.

    I dont think your 30" barrel is the problem myself...
     
  5. Topshot

    Topshot Well-Known Member

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    My Edge has a special cut chamber. It can run with lower pressure than a standard chamber and hold more powder.
    Pressure is not an issue, and case life is good.
    Accuracy is also good, but just not quite as good as with the 92 gn load.
     
  6. Kiwi Nate

    Kiwi Nate Well-Known Member

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    If case life is good and you are sure pressure is low, then yes perhaps it is time to start exploring limitations within other variables.

    I see you have a brake so you probably don't have a whip problem. It is true that the M700 is truly at its limit when laoded to full RUM velocities. I think Dan Lilja got right up this one a while back via an article on his site.

    In my .375RUM, I am able to run a 225 grain Bullet at 3250fps, producing one hole groups at 100 yards (a fairly stout barrel). I can shoot a 260 grain bullet at 3120fps for around .75". On some days, if I get scared of all of that recoil, I shoot all to hell. The M700 is (in theory) at its absolute limits of stress/ load bearing athese velocities.

    Hand holds, trigger let off, grip tension- all have an immensely profound effect on groupings at the power level your are using so start by observing your own practices in order to eliminate these variables. Then again, recoil may be so light due to an effective muzzle brake, as to not suffer from the effects of hand hold position and tension. You will have to observe this for yourself. Is there a high level of recoil? If so, it is likely that hand hold tension/position will be a major factor in accuracy.

    Another variable is pinching within the bedding platform. Check it over and watch for tight areas around the recoil lug (am assuming the rifle is bedded).

    Changes in hand loads will produce yet another set of variables.

    Anyway, those would be the three areas I would look into if I was determined to load the cartridge balls to the walls- assuming you are correct in your initial observations regarding current pressures (everyone gets caught out with pressure problems atleast a few times in their reloading careers).

    As for bridging, I don't think it is a problem in this instance but am so glad somebody is willing to bring the subject up. Not enough people understand the ramifications of powder bridging in the big Magnum cartridges. RoyinIdaho brought up a serious and real issue that occurs from time time and needs to be shared on the boards as he has done in order to warn others.
     
    Last edited: Feb 16, 2010
  7. Tang

    Tang Well-Known Member

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    Not to sound dumb, but I hadn't heard of Bridging in powder before, but I'm still a fairly new handloader.

    Is this something I should be worried with, when dealing with my .300 RUM ? I use RL22, RL25 and Retumbo.
     
  8. Kiwi Nate

    Kiwi Nate Well-Known Member

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    Its not a dumb question at all.

    Powder bridging/ directional ignition and detonation are all terms that have been used over the last few decades in an attempt to describe pressure problems relative to under loading a cartridge.

    If a cartridge is underloaded, the primer flame will burn over the top of the powder coulumn and then down into the powder. In doing so, the optimum burn rate and pressure wave are lost as all of the powder is burnt at once, rather than gradually.

    The problem of detonation has been around since the advent of cased ammunition. Any under loaded ammunition can produce these results although some cartridges and powders seem to display greater problems that others.

    A classic example is Winchester 296 powder in either the 357 or 44 Magnum cartridges. In this instance, the powder is the culprit and if it is underloaded, pressure spikes occur.

    The new super magnums also pose problems, especially the smaller bores. The problem does not occurr as a result of hand loaders deliberately trying to down load. Issues usually arise with starting loads.

    In the 7mm RUM, loads below 89 grains (with all brands of powder), can produce severe pressure spikes as a result of detonation. If I want to run 162 to 180 grain bullet in the RUM, the rifle will hit optimum pressure between 94 and 91 grains of Retumbo. As you can see, there is not a lot of room between max pressure and under loaded/ dangerous pressure. The .44 Magnum is the same (with W296), a small window for loading. Winchester give clear warnings about this in their reloading data.


    [​IMG]
    My crappy picture of bridging/detonation/directional ignition.

    Again, sticking with the 7mmRUM, the reloader can utilize H50BMG to fill the RUM case to full, such as 102- 104 grains behind a 162 grain bullet. Velocity is now 3220fps to 3275fps and the case is full to the bullet base. The downside of this is the extra heat generated by the greater powder charge- goodbye throat. Remington would have been better off, during the design phase of the 7RUM, to stay closer to the Dakota case length of 2.5"- it would have made no difference to goal velocities.

    [​IMG]
    My next crappy picture- optimum burning.

    In my 6.5-55, I can download to nearly half of its usual loading. While this a dangerous excersise, my point is that some cartridges are less forgiving than others with regards to how much you can download. In this instance, I was able to drop 22 grains rather than 3-5 grains in the 7RUM.

    If directional ignition/bridging/detonation occurs in a super magnum, the bolt locks up and has to be beaten open with a mallet. Once the case is extracted, it becomes apparent that the primer has been blown out of the primer pocket and that the head of the case is disfigured, losing most of its head stamp. Velocities over the chronograph do not necessarily read higher or lower than usual. I can only guess that pressure is perhaps somewhere above 80,000psi.

    One last point. If a 7mmRUM is short throated by 50%, it becomes very dangerous. Using the 162 grain bullet weight as an example. Max powder charge with Retumbo is around 91 grains. Detonation occurs at 88 grains.

    Nathan.
     
    Last edited: Feb 17, 2010
  9. Tang

    Tang Well-Known Member

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    Thanks Nate !
     
  10. signature542

    signature542 Well-Known Member

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    It would be interesting to see if someone else is using an action other than the 700 Remmy for an egde build and the results they get.

    Jawz has one on a Mk5 which IMO is stronger I wonder what he has found when loading up.

    Quirk of the cartridge calibre or is it the action?

    Any one have an Edge on a Lawton or other clone action action for comparison?

    No doubt Shawn has built a few over the years?
    If I knew what I know now I would have bought a Lawton 7000 and saved money on the treatments!