Rem 700 Long actions can shoot almost any belt cartridge

[Culpeper]

In other words you've neveractually tried it but speak only from what you've been told. You've never tried putting any of the above mentioned rounds in a standard Rem La action and running them through have you. Blah Blah RUM bull squirt. Do you hunt or just flap?

The RUM action is relieved under the rear receiver ring as well as at the feed ramp.

 

[Nimrodmar10]

The factory 338 Lapua is not a standard LA, it is the same as a RUM.

I have built many rifles on all of these actions, they are all different spec, just like a SA is different, including those built for WSM's & SAUM and those on 222 based cases.

Cheers.

But the action lengths, action screws spacing and magazine length are the same as a regular long action.

 

[Culpeper]

But the action lengths, action screws spacing and magazine length are the same as a regular long action.

ΔL

 

[Philward]

Most if not all detectable magazines have their own feed lips.
And I'll throw another 700 action cut in the mix. The factory 700 DBM actions have no feed lips.

True, ADL and BDL are different than the DBM actions as far as the feed rails. I converted an ADL 7rm to BDL stock with BDL bottom metal, then changed to a Quickclip and finally to a factory DBM. It functions and feeds but not great. The feed rails need widened a bit.

 

[Shane Lindsey]

So I have this 300 WM action sitting here and for the life of me I can't get my 300 RUM ammo to go into the mag...Maybe you can assist???

There are only two Remington 700 action lengths, the "short" action will accept .17 Hornet and up to approximately .308 and the "long" action will accept for example 30-06 and up including belted magnum/longer case calibers with C.O.A.L.'s up to 3.600" including the .458 Lott. There is no need for a longer "super magnum" action.
The Remington 700 long-action and magazine-box will easily accept, feed, shoot and allow extraction of modern belted magnum cartridges with the bolt face sized for .532 rim diameter and with up to C.O.A.L. length of 3.600" without ANY modification other than a barrel change to the desired caliber/case.
A 30-06 or .270-chambered model 700 LA (for example) will accept three (Snap Cap) .375 H&H Magnum rounds into the magazine box and allow the bolt to pick up each round and chamber it as deep as the smaller chamber will allow without the smaller bolt-face extractor (.473") grabbing the rim. This demonstrates that the long action magazine box will handle the magnum cartridges and that the long bolt will pick up the cartridges. (This shows that a Rem 700 30-06 action and magazine is all ready to accept much longer cartridges.)
ALL Remington 700 LA bolts will swap actions, maybe not smoothly and the bolt faces may be for different rim diameters but they will swap!
My Rem 700 in chambered for 8mm Rem Mag will load three .375 H&H Mag Snap Cap rounds into the magazine box and the bolt will (again) pick up each case and push it into the chamber until the larger .375 aluminum bullet stops at the smaller chamber neck and the bolt extractor will engage the the rim properly if jammed home but will require a cleaning rod to force it back out. (Snap Cap rounds are made of aluminum and will not adversely affect the chamber, neck, or lands if contact is made.) I also shoot a Remington 700 chambered in .458 Win Mag and the action is identical to that of the 8mm Rem Mag (the bolts will swap).
The following belted cartridges meet the criteria of factory rim diameter of .532" or .5315" and a C.O.A.L. of 3.600" and are the offspring of the .375 H&H Magnum or one of its derivatives:

7mm Shooting Times Western
.300 H&H magnum
8mm Remington Magnum
.375 H&H Magnum
.400 H&H Magnum
.416 Remington Magnum
.458 Winchestern Magnum (3.340")
.458 Lott

The 8mm Mag and the 7mmSTW have the highest working pressures of 65K and the rest have working pressures of approx. 62K. The 7mmSTW case has the greatest sustained profile, much greater than that of its parent the 375 H&H.
Feel free to disagree but please, only if you have installed or attempted to install a 7mm STW, .375 H&H, or larger caliber belted cartridge barrel with no modifications, into a Remington Long action receiver and had it NOT load, fire and/or extract safely. There are frequently those who say it will not work without "grinding" this or "machining" that and have only B.S. and rumors to back up their erroneous claims, even from at least one major barrel maker.
Come and get me!

So I have this Remington 300 WM sitting here and for the life of me I can't get my 300 RUM ammo to go past the feed rails and into the mag...Maybe you can assist???