Nucleus Long Action 300 RUM build

[verdugo60]

Considering a 300 RUM barrel on my LA Nucleus coming in a month or two. Need help deciding on a stock and bottom metal that will work, would like to shoot 230 bergers.

I'm considering a Manners carbon fill and a proof barrel to be able to carry and reach far out. With the barloc I may screw on a 338 edge barrel occasionally too.

Any potential issues? I'm hoping I don't need an XL action, thus RUM vs 30 Norma.

 

[verdugo60]

..

 

[verdugo60]

Maybe these haven't been out in the wild long enough for people to comment. Anyone who has done a big magnum build on a similar action, what bottom metal/mags should I be looking at for seating 215's or 230's longin the RUM?

 

[Edds]

Using 215 or 230 Berger target bullets in a 300 RUM, you are going to need a minimum cartridge OAL of about 3.750".

 

[verdugo60]

Great, thanks. I'm new to mag fed magnums, should I set it up for a specific bottom metal/mag combo? I seem toremember CIP being one of the longer ones?

 

[Simia Dei]

Do you want to use a DBM or wyatt's magazine box type system? You should be able to seat longer using the wyatt's, I believe their longest box is just under 4" for OAL. If you go down the DBM pathway you could use an Accurate mag 300RUM magazine which will allow for seating to 3.850". They also have a 3 round option if you want a lower profile magazine.

 

[verdugo60]

Hmm, good question. The Wyatt's box seems a bit more practical for COAL and hunting but I might try some ELR comps so the DBM might win out.

 

[wesc]

Did you do this? I’m considering a LA nucleus build for as a switch barrel setup for North American and African big game (not switching day by day but hunt by hunt). I’d like to use Wyatt’s dbm but I was under the impression the nuke wasn’t cut for Wyatt’s or bdls. I know the new mausingfield is but I really like my SA nuke and would rather spend the extra money on barrels.

 

[wesc]

@verdugo60

 

[verdugo60]

I decided to do a 300 PRC build instead of a RUM. In case you haven't been following it's basically a 300 Win Mag with 5 more grains of powder and no belt, with factory ammo from Hornady.

I have a Proof Savage Pre-fit I just headspaced to my Nucleus with the Barloc and I installed my Tac Sport 2 stage trigger. My KRG Bravo comes this week as well as dies and bullets. I need to order a CIP length mag, hoping to shoot it this or next weekend! So far I'm really liking the Nucleus and as a quick change setup it seems fairly doable with the Barloc (not compared to my AI but it's lots cheaper and lighter.) Overall I'm pleased, will report on how she shoots!

 

[j741]

Where did you get a 300 PRC Savage Pre-fit? And what headspace gauges are you using?

 

[Ledzep]

Good call on the PRC. The RUM is a little long for mag feeding heavies.

Any CIP length compatible DBM/chassis/minichassis will work. I went with a Manners mini chassis (CIP length) and accurate mag 3.850" long (3.750" COAL) mags.

 

[wesc]

Good call on the PRC. The RUM is a little long for mag feeding heavies.

Any CIP length compatible DBM/chassis/minichassis will work. I went with a Manners mini chassis (CIP length) and accurate mag 3.850" long (3.750" COAL) mags.

@Ledzep


What you say about "Any CIP length compatible DBM/chassis/minichassis will work" makes sense to me based on both nuke and mausingfield being able to feed CIP length cartridges. That being said, any idea about what made the gen1 mausingfield's geometry is not compatible with a BDL or wyatts mag but the new one is? Does anyone know if the nuke is compatible with these? Sorry to pull a thread resurrection but it was mentioned above and I was hopeful that others had found an answer to this.

 

[verdugo60]

Where did you get a 300 PRC Savage Pre-fit? And what headspace gauges are you using?

Straight from PROOF on the pre-fit. I did a carbon barrel for hunting and the lighter Bravo chassis from KRG. My goal with bipod and optic is to be around 9-10 lbs, which will be pretty damn good for a 2000 yard rifle. Watch out elk, mulies and anything else in a 1.3 mile radius that irks me!

For headspace I just used a virgin piece of Hornady brass for a go gauge and another with tape on the shoulder for a no-go gauge. Worked great.

 

[verdugo60]

Good call on the PRC. The RUM is a little long for mag feeding heavies.

Any CIP length compatible DBM/chassis/minichassis will work. I went with a Manners mini chassis (CIP length) and accurate mag 3.850" long (3.750" COAL) mags.

Cool, I have been shopping mags and may go with accurate. I'm excited to see what this cartridge and barrel can do.

 

[j741]

Straight from PROOF on the pre-fit. I did a carbon barrel for hunting and the lighter Bravo chassis from KRG. My goal with bipod and optic is to be around 9-10 lbs, which will be pretty damn good for a 2000 yard rifle. Watch out elk, mulies and anything else in a 1.3 mile radius that irks me!

For headspace I just used a virgin piece of Hornady brass for a go gauge and another with tape on the shoulder for a no-go gauge. Worked great.

Thanks. I didn't see it listed on theirs site. Will just give them a call.

Nice tip on the improvised 'gauges'.

 

[Ledzep]

@Ledzep


What you say about "Any CIP length compatible DBM/chassis/minichassis will work" makes sense to me based on both nuke and mausingfield being able to feed CIP length cartridges. That being said, any idea about what made the gen1 mausingfield's geometry is not compatible with a BDL or wyatts mag but the new one is? Does anyone know if the nuke is compatible with these? Sorry to pull a thread resurrection but it was mentioned above and I was hopeful that others had found an answer to this.

Good question for ARC. It looks like it could work with internal box bottom metal to me ( very similar to a m700s magazine opening vs. my early mausingfield that is much tighter) but I've never seen it so I can't say 100%.

 

[G.I.Joe]

I decided to do a 300 PRC build instead of a RUM. In case you haven't been following it's basically a 300 Win Mag with 5 more grains of powder and no belt, with factory ammo from Hornady.

I have a Proof Savage Pre-fit I just headspaced to my Nucleus with the Barloc and I installed my Tac Sport 2 stage trigger. My KRG Bravo comes this week as well as dies and bullets. I need to order a CIP length mag, hoping to shoot it this or next weekend! So far I'm really liking the Nucleus and as a quick change setup it seems fairly doable with the Barloc (not compared to my AI but it's lots cheaper and lighter.) Overall I'm pleased, will report on how she shoots!

@verdugo60 , sorry to revive this thread, but I'm looking to do a similar build as yours. I was wondering how the PRC rounds feed into your Nucleus. I wasn't sure that CIP length mags would work on the Nucleus since ARC's website notes that the Nucleus is designed for 3.78" magazines, whereas CIP mags are 3.85". Could you give an update on how your build is functioning? TIA

 

[Ledzep]

I don't have a barrel on yet but my LA nuke feeds 300 prc dummies out of accurate mag CIP magazines perfectly (bare action in my manners CIP mini chassis T2a).

 

[chadrp]

@verdugo60 , sorry to revive this thread, but I'm looking to do a similar build as yours. I was wondering how the PRC rounds feed into your Nucleus. I wasn't sure that CIP length mags would work on the Nucleus since ARC's website notes that the Nucleus is designed for 3.78" magazines, whereas CIP mags are 3.85". Could you give an update on how your build is functioning? TIA

In asking ARC about the mag length on the LA as I also want to do a 300 PRC, the length ARC has listed is internal mag length so they are supposed to feed fine from cip length mags. I agree it's a little confusing when you have a dimension and it's not listed internal or external with the slightly shorter version mag that is the same length externally.

 

[Ledzep]

Hmm I wonder if that didn't change recently (last 2-3 months?)... I seem to remember it saying something about Cartridge OAL being 3.78" when I ordered.

 

[chadrp]

Yeah, if it said COAL that would be better, but it just says mag length. So I wasnt exactly sure what that meant, was it internal so 3.85s work or external so you have to use 3.775....So I called Arc, and they said 3.78 was max internal mag length so using 3.85 mags wouldnt be an issue.

 

[Steel head]

View attachment 7079053
Yeah, if it said COAL that would be better, but it just says mag length. Does that mean internal so 3.85s work or external so you have to use 3.775....Arc said internal so 3.85s shouldn't be an issue but I haven't ordered one yet to know for certain.

I can tell you that on the short action a 2.94” loaded round will cycle and extract easily.

 

[Ledzep]

To be clear, 3.85" long magazines work. 3.78" is the COAL max. I'll measure my dummy but it requires a CIP mag to fit and it works from a feeding standpoint. Should get the barrel chambered up this afternoon to verify everything, but the mags fit as expected.

 

[chadrp]

To be clear, 3.85" long magazines work. 3.78" is the COAL max. I'll measure my dummy but it requires a CIP mag to fit and it works from a feeding standpoint. Should get the barrel chambered up this afternoon to verify everything, but the mags fit as expected.

Agreed, I edited my last post to try and make my muddied waters more clear. Lol Looking forward to doing a Nucleus 300 prc in the near future.

 

[jmw]

I have a Mausingfield running 300 Norma from CIP mag and a friend has a nucleus running 300 win from a CIP length mag. They do work with CIP length mags.

 

[G.I.Joe]

Thanks to everyone for the info. I originally bought my LA Nucleus to do a 300 Win build, but I'm gravitating toward the 300 PRC now.

 

[Ledzep]

300 PRC is the way to go. You can do about the same thing with a 300 win mag, but it takes a special reamer, dies set up to headspace on the shoulder instead of the belt, etc. etc... The PRC SAAMI spec reamer might as well be a "match" reamer, no belt, no BS. Avoid a couple potential headaches.

Got my barrel put on today, can't wait to shoot it.

 

[fmillik]

Here to revive this thread.

I am looking to do a switch barrel build as well off of an ARC Nucleus Long Action, and I was thinking, since the Nucleus is a "CRF" action, it would be able to handle short action cartridges particularly well.

I am planning on doing both 6.5 PRC and 300 PRC, and merely switching barrels, since they both use the same bolt-face, and have the same case width.

What do you guys think?