Re: Rem 700 action how much chamber pressure is safe?
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.
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