Rem 700 action how much chamber pressure is safe?

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by locotrician, Mar 15, 2009.

  1. locotrician

    locotrician Banned

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    im sure it has been asked before but my searching did not yield good information. I see many people building the .338 edge on the 700 action and i am looking at the .338 lapua, i know it has been done on a rem 700 action as well but is it safe ? what are the pressure differences between the two and is there a consensus on how much chamber pressure is safe in the rem 700? i dont know if i feel safe if the lapua is at the very top of the safe pressure level.
     
  2. jwp475

    jwp475 Well-Known Member

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    Remington chambers the 338 Lapua in the 700 action and it has been thourolly tested for safety

    My 338 Lapua is built on the 700 action and I have experienced zero problems. Many top smiths will build on the 700 action


    Here is mine

    [​IMG]


    [​IMG]
     

  3. locotrician

    locotrician Banned

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    nice looking rifle and congrats on the bull...thanks for the info.
     
  4. jwp475

    jwp475 Well-Known Member

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  5. john_m44

    john_m44 Well-Known Member

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    I had one built on a 700. I haven't had any problems.

    [​IMG]
     
  6. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    When you look at max chamber pressure concerning the Remington M700, its really not that simple just to reply to a simple question.

    If you take a Rem 700 chambered in 223, the receiver would take pretty much anything you could put to it, well over 100,000 psi. Certainly not saying it should be loaded extremely hot but the small case head of the 223 really does not tranpose alot of chamber pressure to the bolt face.

    The larger the case head size, the lower the breaking point in chamber pressure will be for any receiver.

    For example and this is just an example, suppose the Rem 700 will support 120,000 psi with a 223 Rem case head diameter. Jump up to the 30-06 case head size and that would likely drop to 100,000 psi.

    Step up to the belted magnum case head size and that would likely drop to 85,000 psi. Step up to the Lapua class case head and that peak would drop to say 75,000 psi.

    Its all a function of chamber pressure and the amount of area that the case head presses back against the bolt with.

    Now remember all these numbers are strictly for example.

    Where you can get into trouble though is that many that hand load for a rifle will start with load development and increase powder charges until they top out in pressure, or at least that they think is topping out in pressure.

    If you have a properly accurized receiver, you will see far fewer pressure warning signs then with a factory rifle.

    If your shooting a 300 RUM for example, you will get a hair over 65,000 psi and your primer pockets will start to loosen up dramatically giving you an OBVIOUS sign that your way over pressure.

    The problem with the Lapua is that by the time you reach this high pressure sign, that being primer pockets loosening, you will be WAY over the safe working design levels of the Rem 700. A 338 Lapua case made by Lapua will take 70,000 psi and show no real signs of primer pockets loosening, especially with only one or two firings. Does this mean its safe.........

    A Rem 700 will certainly handle a properly loaded 338 Lapua load. That being roughly 2700-2750 fps with a 300 gr SMK in a 26-27" barrel length. In a 30" barrel you will see around 2800-2850 fps. With loads in this range, the Rem 700 is more then strong enough to handle this level of load long term.

    The problem is when someone that does not have a good amount of experience loads the Lapua up higher then it should be. In that case, it WILL stress the Rem 700. Will it come loose, no it will not but over time, it can stress the receiver dramatically.

    I personally will not chamber a stainless Rem 700 for a Lapua class chamber. The reason again is not that the Rem 700 will not handle a properly loaded Lapua, even the Stainless will easily handle this level, its just in the event that someone pushes things to hard and do not realize what they are doing.

    With a stainless receiver, if you push things to hard, you WILL set the bolt lug supports back in the receiver, especially the bottom lug support in the Rem 700 as its not supported by alot of steel. This happens to a greater degree then the chrome moly(blued) receivers simply because chrome moly is harder and will resist set back better then stainless.

    This is not opinion, I have seen it actually happen. I put together a 7mm AM for a customer right when I came out with the wildcat. I had a Rem 700 personally in this same chambering and was more then happy with it. Mine was a chrome moly receiver, the customers was a stainless.

    After several months, I got a call from the customer that he was having problems opening the bolt on a fired round. Told him to bring the rifle and load data and ammo he was using.

    The rifle had a 26" Lilja 1-7 barrel and was loading the 200 gr ULD RBBT to a legit 3300 fps. Now in a 30" barrel, this would be about tops, in a 26" barrel, VERY HOT LOAD.

    He said the rifle performed extremely well for around 75 rounds. After that, he started to notice that the bolt was getting hard to open. Not dramatically but noticable. He backed off his load to 3250 fps but still the problem was there and was getting worse until he had dropped his load to 3000 fps and could hardly open the bolt after firing a round. Total rounds down the bore was less then 150 rounds.

    First off I told him his load was way to hot, at least his 3300 fps load. 3200 fps was about right. So why was his 3000 fps load doing this????

    I could not figure it out so I told him to leave the rifle and the next day I took the rifle apart. It only took a few measurement from the receiver face to the bolt lug supports to tell me what was happening. From the receiver face to the bottom bolt lug support was a full 7 thou longer then the top measurement....... When I built the rifle, this measurement was less then 0.0002" difference....

    Measured the bolt lugs, they were nearly identical in length as they should have been so the bolt lugs themselves were not compressing, only the steel behind them....

    So why was the bolt locking up so tightly when fired. Well, the bolt lug support surface was compressing faster away from the cam ramp so when you chambered a round, the bolt lug would climb up the cam and onto the surface but when fired, the bolt would be forced back down the declined surface, effectively making a mechanical lock.

    After I saw this, I measured some of his fired case with a 0.0005" dial indicater and it was clear what was happening and this was just more proof of it.

    I wanted to test this more, so I took my personal rifle which had a 27" Lilja of the same twist and loaded it up to 3300 fps with this same bullet. I shot 100 round through the rifle at this level. And I can say for a fact that not one of the primer pockets loosened up any noticable amount in the Lapua cases. Certainly not a sign that the load was safe, only that the Lapua case is brutally strong.

    After those 100 rounds which were on top of nearly 400 rounds down the bore I had already fired, I pulled the barrel and made the same measurements. In this case, the measurement from the receiver face to the bottom bolt lug support was 1.5 thou longer. It to had set back but but dramatically less then the stainless receiver....

    From that point on, I made it a shop policy to never built a Rem 700 stainless receiver into a Lapua class chambered rifle.

    Again, please do not read this and start saying that Kirby Allen does not believe the Rem 700 is strong enough to be chambered in the 338 Lapua, that is simply not the case.

    All I am saying and I will say it again to be clear, if your using standard printed 338 Lapua load data, even top end printed load data, you will be fine with a properly built Rem 700, chrome moly or stainless.

    IF you load hot loads thinking you can load to the limits of the 338 Lapua case in a Rem 700, you will definatly push the Rem 700 harder then it should ever be pushed to and far past its design limits.

    Keep a head on your shoulder, do not get caught up in the "grass is always greener" theory, load to standard load levels and you will be fine and very happy with a very long life of your rifle. Push things to hard and you may see just how bad things can get if a Rem 700 or any factory receiver is mistreated.

    As a side note, I fully believe that a properly built and accurized Rem 700 is as strong as any factory receiver on the market including the Wby MkV and Sako TRG-S or M995. Over load any of these and you will see the same results, and they will be bad. Load the Lapua properly, and you will have nothing but great results.

    Nuff ranting....
     
  7. locotrician

    locotrician Banned

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    hey Kirby, thanks for the reply and the great information that is exactly what i was hoping for. I have another question now , for you or anyone else that may know the answer. Why/ what makes a rem 700 clone built by any of the many action manufacturers any stronger than the rem 700, if it is built to the same dimensions what is the difference?(or are the clones slightly different dimensionally form the actual rem 700?) is it simply a matter of the grade/quality of the steel used ? or a different machining process ? or ?????? all input much appreciated
     
  8. Bart B

    Bart B Well-Known Member

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    I don't think it's safe to load or use ammo with peak pressures getting even close to the action's limit. The reason is the case is weaker than the action and it'll have problems long before the action does. I read some years ago that the Rem. 7XX actions were good for about 130,000 to 140,000 pounds psi (impulse pressure, when fired) before bolt lug setback started.

    Cartridge brass starts to extrude at about 75,000 pounds psi (about 65,000 cup). If the case head starts extruding back into bolt face cut-outs, I think one has two choices:

    * Reduce the load (less powder, lighter bullet, etc.) and shoot safe.

    * Satisfy your egos and use that load (or a heavier one) and shoot happily and dangerously.

    Therefore, I think one should limit chamber pressure to what the case safely allows, not what the action does.
     
  9. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    The custom receivers may appear to be the same as the Rem 700 but they certainly are not where it matters. They have longer, wider and thicker bolt lugs that have a much higher shear point.

    More importantly, they will have more steel behind the bolt lugs in the receiver. May only be 50 thou thicker but this is a dramatic amount when it comes to strength.

    Also, many of them have slightly larger receiver threads so that the barrel threads are larger in diameter which also helps control any stretching of the chamber area when fired with a larger diameter chambering.

    Again, they may appear to be the same but that is externally.

    Another thing to consider is that you can manipulate heat treating and use different materials to make a very similiar product much stronger. There is much more then meets the eye with most of these custom receivers.
     
  10. eddybo

    eddybo Well-Known Member

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    Thanks for the info Kirby.
     
  11. J E Custom

    J E Custom Well-Known Member

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    I stoped loading maximum load years ago because of the problems encountered
    with it.

    I use a different approach to more velocity without more pressure ( A bigger case )
    and slower powder with a longer barrel.

    With so many choices there is no reason to push your equiptment or your luck.

    And the only reason other than Kirbys is if you open the bolt head up to far you
    all but eliminate the ring/shroud around the case head that protects you from
    a face full of high pressure gas from a blown case.

    If you take your car and put it on a track and drive it wide open you woun't get far
    but if you drive it like it was designed for it will last many miles.

    Same thing with a firearm.

    Also factory rifles have a 50% safety factor biult in and as you go above the designed
    pressure you eat into this very fast.

    Good Post Kirby you explained it very well

    J E CUSTOM
     
  12. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    This is great info. Brings me to a question. How does one know when he is at max pressure when loading a wildcat based on a Lapua case? My question more specifically. I have a 30-338Lap imp built on a Sako M995 action. There is no load data to reference. I back my loads off from any kind of sticky bolt, but the case is pretty straight, so I experience some stickiness on the initial lift, but not beyond that. I feel like I run it pretty hard, but I really don't know. I have used Kirby's numbers for his 300AX as a guide line, but after reading his post here, I have some doubt. I had always thought that the Sako action was the heaviest factory action.

    Sorry about the hi jack, but I would sure like to see more input if anybody has more to share.

    Thanks, Steve
     
  13. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    One thing I did when developing my wildcats based on the 338 Lapua case was to do some load development using the Norma made Lapua case which is a great case but much softer then the Lapua and it will tell you more about chamber pressure then the Lapua case.

    In fact, the Norma cases are very similiar in hardness as the Remington RUM cases. Good cases and they will certainly tell you when your over the top.

    I then used that data as a baseline for top end loads even when using the Lapua case.

    Basically, look at the chambering your using, compare it to similiar chamberings and you can basically figure out where you should be. In your case, you have a 300 Lapua basically.

    If you look at the parent case, the 338 Lapua and compare it to a 338 Edge, the performance is nearly identical with the Lapua maybe getting a 50 fps boost in performance, MAYBE.

    With that in mind, you know what to expect comparing the 338 Lapua to the 338 Edge which is basically the 338-300 RUM.

    If you know that, you can expect that the 30-338 Lapua will basically get you the same performance as the 300 RUM, again, perhaps 50-75 fps more.

    Now if you have an improved version, you will get 100-125 fps more then the RUM. You just have to take a realistic look at whats out there with similiar case capacity.

    If your getting 400 fps over what the 300 RUM will get you, obviously, your overloading the 300-338 Lapua. Just need a realistic point of view and some common sense. That with the help of a chronograph and you will be in good shape.
     
  14. RockyMtnMT

    RockyMtnMT Official LRH Sponsor

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    Thanks Kirby.

    I have also paid attention to the 300RUM as a guide line. Have always stayed within 150fps of the RUM. Considering my barrel is 30" I think I am ok.

    Thanks again Kirby. Hope things are well for you.

    Steve