Re-chamber .300WM to .300 PRC?

[memilanuk]

Just kind of kicking an idea around... I've got a Krieger .300WM barrel (25" heavy Palma 10 tw) with very low round count. Never was that excited about the whole 'belted magnum' thing; more so now that better non-belted options are available.

I'm considering having the existing barrel re-chambered, knowing that barrel life isn't going to be the same as if it were new, rather than trying to sell a (lightly) used .300WM barrel. Figure I'll get my feet wet, and play around a bit while I order the barrel I really want.

Yes, the action I'm planning on using takes CIP mags, so OAL is not an issue

Any *mechanical* reasons why this (rechambering from one to the other) wouldn't work?

 

[DaveTooley]

Yes it would have to be set back some. I haven't done the math yet but somewhere around .200" sounds about right. Maybe a bit more depending on how the neck diameters match up.

 

[Catfur]

I'm considering having the existing barrel re-chambered, knowing that barrel life isn't going to be the same as if it were new, [...]

I have had rechambers last longer than the original chambering did in competition rifles (6XC, cut tenon off, rethread, rechamber).

 

[Scarface26]

View attachment 1104797

Oops wrong pic...


View attachment 1104798


Pretty sure you have to set the barrel back.... Been thinking of this myself

It'd be a good idea to keep this forum family friendly. Simo, sir, I'd encourage you to delete that photo. None of us need to see that garbage on a shooting website. Or any other website for that matter.

God bless America

 

[theallcineyes]

I sure wouldn't do it. I feel the 300 win has plenty to offer you. With 210's you can get good velocity. Good brass is available and throat life is great with the Win. I feel the 300 and 210's are a great gun out to 1000 yards for even Elk. The win will do just fine for this and practice is cheaper too.

 

[Kurz]

 

[memilanuk]

In all fairness to the .300WM that I have... the gunsmith throated it long for 200+ gn bullets. I don't recall the exact OAL at the moment, but it's somewhere closer to 3.650-3.700" with a B215 Hybrid. Last time I did load development with it, I think it was running just a tick over 2800 with H1000 in Winchester cases. They shot well, but the cull rate to actually end up with usable brass was outrageous. Since then I picked up some Sig brass in trade, but haven't touched it. From the sounds of other people's loads that get mentioned when discussing .300WM vs. .300 PRC... my .300WM load is pretty 'soft', probably a 'low' node, rather than a higher/faster one.

Debating whether to shoot it as is until it dies, part it out and apply the funds to a new barrel, brass and dies, or rechamber it and part out the dies and brass while waiting on the new barrel. I guess another option is to part it out, get a pre-fit (few weeks) while I wait on the barrel I want - for some reason I have a hankerin' to try a gain twist - which could be months.

 

[hogpatrol]

I ran this through AG's rechambering tool and they're saying it's not just a straight up job but there's a workaround.
My number crunching says at least .075 setback.

.300 Winchester Magnum

.300 PRC

 

[Kurz]

Yes it would have to be set back some.

they're saying it's not just a straight up job but there's a workaround.
My number crunching says at least .075 setback.

Yes there's a set back, Dave stated it in the second post and I agreed although I didn't write it out, when I posted the drawings. Practical, hands-on experience dictates that set backs are a common procedure and like some assumptions, I skip over those words. I would go a bit farther because of the throat and freebore length.

 

[D.Stone]

Hey Monty,

I think I have shot a good amount of 300WM ammo at far enough distances to have a decent grasp on how capable it is.

The 215 Berger Hybrid is a perfect match for the 300WM. I am safely getting 2950fps with the 215 Berger Hybrid with Norma brass and H1000 powder. I've been in GA for a long time, so I typically shoot in very hot and humid weather.


The Norma brass is a lot lighter than others I have compared it to, so I might be abusing that extra case capacity. However the max load I have tested topped out at 3050fps, and I stopped there because I don't like to push safe limits.

My 300WM load is for all practical purposes on par with a lot of 300 Norma loads. My friend won the Light Gun class shooting my rifle in the first SE ELR match with me coaching him. I took 2nd while he was coaching me.

As far as the belt goes...I haven't had a problem with it and I think my Norma brass is on it 6th firing. I just use a full length RCBS sizing die with a bushing to resize my brass. I think the A191 Chamber reamer my gunsmith uses is set up so that the case headspaces off of the shoulder instead of the belt..and I think that was something that was common when the 30 caliber rule was still a thing for sling shooting.

One of the other things to consider is that Lapua/Berger is planning on making 300WM brass at some point...that might be important if you do not like Hornady brass for the 300PRC. I personally have had decent experience with Hornady brass but that might be because PRS is not as discriminating as F-Class.

 

[memilanuk]

ran this through AG's rechambering tool

Tell me more... what is this 'rechambering tool' of which you speak? I'm assuming it's something online?

@D.Stone funny you should pop up... I spent last weekend with Yoda and Econ @ the Boomer Shoot

because PRS is not as discriminating as F-Class.

Not even gonna touch that one with a ten-foot pole...

 

[hogpatrol]

Tell me more... what is this 'rechambering tool' of which you speak? I'm assuming it's something online?

Ammoguide.com is the website with the rechambering tool.

https://ammoguide.com/cgi-bin/aichamber.cgi?sn=BtFRIcTVnk

 

[memilanuk]

Oh geez... there's a blast from the past. I haven't been to AmmoGuide for years and years.

Too bad they don't have an additional parameter for 'assume setback of n.nn inches'!

Thanks for the tip!

 

[Beeman]

I would stick with the 300 Win Mag. Shooting the 215's at 3000 fps out of mine with H1000. This was a custom reamer used and has performed very well. On game performance is also excellent.

 

[D.Stone]

Tell me more... what is this 'rechambering tool' of which you speak? I'm assuming it's something online?

@D.Stone funny you should pop up... I spent last weekend with Yoda and Econ @ the Boomer Shoot



Not even gonna touch that one with a ten-foot pole...

Oh trust me...that really old guy was bragging about his silly little English gun. Unfortunately it looks like he left the 300WM at home and still hasn't got on-board with the recipe I gave him 2 years ago. Finally got him to try something other than Leupold or Unertl scopes though.

 

[memilanuk]

LOL... he was still rubbing up on that thing Still lugging the 'God' scope around too

I'm kind of leaning towards keeping this thing as a .300WM for now. I like what I see of the .300 PRC, and while I do have my quibbles about Hornady brass, it does seem to work well enough in my 6.5 CM. I'm not quite as enthused about the reloading die situation; I think I may get some parts on order - barrel, reamer, sizing die, maybe brass... and hold my breath for a decent seating die to come on the market (c'mon, Forster, c'mon!) while I shoot this barrel some more.

 

[francesco2011]

Hi everyone. New 300prc.io project I live in Italy and it's not so easy to buy action for rifles, I wanted to use that of the remington mlr in 300wm. Do you think it's a good long action to start the project ???

 

[DaveTooley]

Hi everyone. New 300prc.io project I live in Italy and it's not so easy to buy action for rifles, I wanted to use that of the remington mlr in 300wm. Do you think it's a good long action to start the project ???

It will work for your project.

 

[Zero333]

Hey Monty,

I think I have shot a good amount of 300WM ammo at far enough distances to have a decent grasp on how capable it is.

The 215 Berger Hybrid is a perfect match for the 300WM. I am safely getting 2950fps with the 215 Berger Hybrid with Norma brass and H1000 powder. I've been in GA for a long time, so I typically shoot in very hot and humid weather.


The Norma brass is a lot lighter than others I have compared it to, so I might be abusing that extra case capacity. However the max load I have tested topped out at 3050fps, and I stopped there because I don't like to push safe limits.

My 300WM load is for all practical purposes on par with a lot of 300 Norma loads. My friend won the Light Gun class shooting my rifle in the first SE ELR match with me coaching him. I took 2nd while he was coaching me.

As far as the belt goes...I haven't had a problem with it and I think my Norma brass is on it 6th firing. I just use a full length RCBS sizing die with a bushing to resize my brass. I think the A191 Chamber reamer my gunsmith uses is set up so that the case headspaces off of the shoulder instead of the belt..and I think that was something that was common when the 30 caliber rule was still a thing for sling shooting.

One of the other things to consider is that Lapua/Berger is planning on making 300WM brass at some point...that might be important if you do not like Hornady brass for the 300PRC. I personally have had decent experience with Hornady brass but that might be because PRS is not as discriminating as F-Class.

Great info.

I too have no desire to switch from 300winmag to 300prc because I've experienced no downsides with the belted case. Even if the 300prc could push maybe 100 fps faster, that 100 fps extra will never turn a miss into a hit.

I started using RL-33 for 220-240 grainers and can't say enough good things about it. With out being anywhere near max I'm shooting 240smk at 2,760 fps from a 26" barrel that's throated for 180's !!
This is in F.C. brass from their FGMM loaded ammo.
I stopped the 240smk load work up at 2,840 fps with out a hint of pressure. Didn't care to go higher because I had a extremely flat velocity spot at 2,760 fps. with very low ES... Flat spot was at least 1.0 gr wide and during testing at 200 meters the POI was identical over the spread of 4 gr.

 

[YEW PLUCKER]

Great info.

I too have no desire to switch from 300winmag to 300prc because I've experienced no downsides with the belted case. Even if the 300prc could push maybe 100 fps faster, that 100 fps extra will never turn a miss into a hit.

I started using RL-33 for 220-240 grainers and can't say enough good things about it. With out being anywhere near max I'm shooting 240smk at 2,760 fps from a 26" barrel that's throated for 180's !!
This is in F.C. brass from their FGMM loaded ammo.
I stopped the 240smk load work up at 2,840 fps with out a hint of pressure. Didn't care to go higher because I had a extremely flat velocity spot at 2,760 fps. with very low ES... Flat spot was at least 1.0 gr wide and during testing at 200 meters the POI was identical over the spread of 4 gr.

That is good info..