Converting a 300wm to 300nm

[odoylerules]

I'm thinking of re-barreling my win mag to another caliber, and really like the 300 Norma. I know the Norma has the lapua bolt face. Can this be done?What needs to happen? New bolt? Any work to the action itself? Should I do this?
Thanks guys

 

[yobuck]

Well you know what is said about opinions.
The cartridge was in fact designed with Rem 700 actions in mind. I do know at least one guy who has one on a Rem 700 and it seems to do very well.
I would personally prefer, and do in fact have one on a larger bolt face, like a Mark five Weatherby.

 

[IdahoCTD]

I have 2 300 Norma Imp's on Remington actions and it's not as easy as a new bolt or opening up the existing one. A Norma case won't fit between the feed rails of a 300wm action so quite a bit of work needs to happen there to get them to feed correctly. The 300 Norma is only 2.5" long compared to the 2.62" of a 300wm. The barrel would have to be set back two turns to clean up the old chamber provided the neck diameter on the Norma is larger then the 300wm. A factory reamer is but my reamer, for a tighter no turn neck isn't. Otherwise it's a rebarrel. One other thing......there is a reason Remington only makes their 338 Lapua guns on chromoly actions. I wouldn't do a stainless action.

 

[martinakl]

I'm thinking of re-barreling my win mag to another caliber, and really like the 300 Norma. I know the Norma has the lapua bolt face. Can this be done?What needs to happen? New bolt? Any work to the action itself? Should I do this?
Thanks guys

What make/model of rifle are you trying to convert?

 

[odoylerules]

Remington 700

 

[tbrice23]

One other thing......there is a reason Remington only makes their 338 Lapua guns on chromoly actions. I wouldn't do a stainless action.

Is this because CM is "tougher"/better able to handle sheer stress. Where SS is too "hard"/less tensile strength?

 

[Aoudad shooter1975]

I built mine of a weatherby...easy as pie....

 

[WildRose]

I have 2 300 Norma Imp's on Remington actions and it's not as easy as a new bolt or opening up the existing one. A Norma case won't fit between the feed rails of a 300wm action so quite a bit of work needs to happen there to get them to feed correctly. The 300 Norma is only 2.5" long compared to the 2.62" of a 300wm. The barrel would have to be set back two turns to clean up the old chamber provided the neck diameter on the Norma is larger then the 300wm. A factory reamer is but my reamer, for a tighter no turn neck isn't. Otherwise it's a rebarrel. One other thing......there is a reason Remington only makes their 338 Lapua guns on chromoly actions. I wouldn't do a stainless action.

I had to open up the feed rails on an upgrade from .300wm to .300 Rum on a Remington action, even with basic tools I found it a pretty simple process that only took maybe a half hour.

You have me curious though, what is the problem with using a stainless action with the Lapua bolt face sized cartridges?

 

[IdahoCTD]

A RUM and a 300 Norma are 2 different animals when it comes to feeding in a Remington action. The Norma is quite a bit fatter and getting it to feed through the feed rails, even with a center feed mag, isn't as easy as converting a 300wm to a 300RUM.

Chromoly is stronger then 416SS. It's the same reason Krieger won't make barrel contours as small in stainless as chromoly. Well they say they don't do it because stainless doesn't do well in cold weather but it's still a strength issue. The same thing applies to muzzle brakes. If you want them to stand up to long term rapid firing (think AR15's and AR10's) it's best to use chromoly and nitride them. Even hardened 416 can't hang with chromoly. Chromoly actions will experience lug set back with a 338 Lapua bolt face if you push them as hard as a custom. It usually takes a bit to be able to measure the change in headspace but it does happen.

 

[AKdan]

IdahoCTD -

I am curious as to why you think that 416 Stainless is not as strong as 4130 Steel.
The yield strength of 416 is greater than 4130 at equal hardness. The ultimate yield of 416 varies a lot, but the critical strength is fairly equal favoring 416. This is of course contingent on the heat treatment...I suspect that the difference between a Remington action of either metal and a custom job of either metal is the control of the processes for heat treatment of the steel AND then the precision of the final machine work. I personally have no qualms with lapua bolt face on a Remington receiver of either 416 or 4130. I would however not do anything to reduce the hardness (tempering, which includes SOME processes of nitriding) and would use a bolt that was treated to a specific hardness and machined with tighter tolerances and quality than perhaps a Factory unit.

I may not be aware of something and would like to learn more as I have enjoyed studying the subject to some depth. Perhaps we could start a new thread to gather together other people who know more about metallurgy then myself. I built a 338 Lapua on a 4130 (ultramag) Action with a PTG bolt(4130). I did this based on a recommendation that the 4130 steel would be more resistant to Lug setback. I started studying about the properties of various steel researching nitriding and am now regretting not having used a Stainless receiver for corrosion resistance as there is no calculable difference in strength(unless you have each action Rockwell tested).

To the Original Poster.-

Setting up a Remington to accept the Lapua BF was simple with a PTG bolt. I am very happy with it although I had mine fluted with the Large spiral fluting and it is not as glassy as my minimally fluted bolts. Opening up the feed rails is ......easy... you wont want to actually use them as the action will likely not feed well in a stagger set up. I tried to use an ultramag extended box but could not get the rounds to feed without a second round popping up during rapid bolt manipulation. The Wyatts center feed mag resolved this issue and I machined the feed lips for the center feed/ DBM. The downside to the Rem 700(or clone) with a floor plate and a Lapua sized case is that you are limited to 2 rounds in the magazine unless you run a DBM set-up. I am planning to build a switch-barrel 300/338/375 Norma off a Remington or Clone. Good Luck with your build.

Thanks,

Dan

 

[Litehiker]

This is an excellent conversion choice. You will gain some ballistic advantage in this conversion and very experienced long range instructors like Todd Hodnett prefer this "medium" magnum cartridge.

Also the US military is strongly considering replacing the M240 7.62 x 51 NATO medium machine gun with General Dynamics' new low recoil medium machine gun chambered in yes, .300 Norma magnum, for an amazing ballistic "overmatch" to Combloc ammo. (GOOGLE it)
General Dynamics chose the .300 NM for its great ballistics and the fact that it runs in a belt fed MG better than the .300 Lapua magnum. Their MG is lighter than even the lightened M240 but, yes, the ammo is 10% heavier. It's a good trade-off for those ridge top-to-ridgetop fights in places like Afghanistan or other "Stans" and alpine areas, not to mention wide open plains.

Still, the .300 Win mag is close, as in horseshoes, etc. I own both hunting and target .300 WM rifles and don't feel at any disadvantage. BUT... if I need to re-barrel the target rifle it will be in .300 NM.

Eric B.

 

[IdahoCTD]

Yes 416 stainless should be stronger in theory but in a Remington stainless action it's not. I machine heat treated 416SS (Rc 28-32) on a daily basis and have quite a bit of experience with it. I've had some heat treated to 40 Rc and played with it too. I've never Rc tested a Remington action but if I had to guess that is why they aren't as strong as the chromoly actions. I could probably get it done fairly easy as I have a half dozen of both actions in the safe and can have the shop that does my heat treating do it but I haven't had the desire to do so. There are numerous custom actions using 416 stainless that are quite strong. Look at Defiance for example. Their bolt diameter is even larger then a Remington at .750", making the lugs smaller, and they don't have issues. I have a Defiance on my 30-338 Lapua Improved. I have Remington actions on 2) 30-338 Norma Imp's and a 30-378 Weatherby Imp. One with a modified Remington bolt and the other 2 with PTG bolts. I ran some pretty hot loads through my 30-378 Imp and the headspace grew .001+". I shot 150gr bullets almost 4100fps, 165's at 3850fps, and 210's at 3550fps in a 30" barrel.

You can always call Remington and ask the specs on their actions plus ask them why they don't make a Lapua in stainless. It make take you awhile to get the right person to answer your questions, if you do at all.

 

[AKdan]

Thanks for the reply. I think you may be correct that finding the right person at Remington to answer a technical question might be challenging. They do build their XCRII Tactical on a 416SS action. I had one a few years ago and it was stainless. I do find it interesting that many argue against the remington action being used for lapua bolt faces and then, as you said, make a smaller lug. kinda defeats the purpose. It really has to do with the specs for heat treating. Probably the best case for purchasing a quality custom action, but precision heat treating is not a sexy topic like precision machining. I found one source a while ago that claimed that Remington aims for a RC of 38. I will look for it again. It state that RC of 38 was optimal for hardness, durability, and elasticity...Looks like we need to find someone with a bunch of actions for some testing. Thanks for the reply.

Dan

 

[IdahoCTD]

That's interesting about the XCR. Maybe they worked out their heat treating to make it work in a stainless action or they just don't care. Bean counters don't usually make the wisest decisions. That is probably why Remington is in bankruptcy. They never use to build them on stainless actions. I've seen 300 RUM's experience growing headspace on SS actions if pushed hard. I ran some 180's 3650fps in one of my RUM's. The brass handles it for one shot and then the primer pockets are toast. You can do the same thing with a 338 Edge using H-1000 and 300gr bullets. The normal node is 2825 ish but the next one up is 2950+. I don't recommend doing any of those things but I've done it.

Most custom actions use similar Rc numbers.