.300WM to .338LM Chassis Modification Possible?

[Boyydavid]

I’ve been trying to research to see if modifying a .300WM chassis to accept .338LM is possible?

I haven’t been able to find much and I’m very new to this topic so excuse if this sounds idiotic.

If I'm going to hand feed my rifle, then this wouldn’t pose a problem as long as using the correct bolt and barrel.
The main problem comes from mag feeding a 338 Lapua from a chassis that is originally for a 300WM.

From what I gathered and correct me on any information that I could’ve interpreted wrong:

300WM has a COAL of 3.34”
338 Lapua has a COAL of 3.681”

That equals to .341” too big of a round to mag feed a 338 Lapua into the chassis.

Is it possible to mill out the chassis slightly bigger, accept a slightly larger mag like a CIP length mag for 338 Lapua and for it to work?

In theory this sounds like it’ll work in my head, but then again I could be wrong. So I’m seeing if anyone has experience in this case to help answer some questions or if they’ve tried this and if it succeeded or failed.

 

[Supersubes]

Be more specific with the exact parts you want to use.

 

[supercorndogs]

The standard length long AI mag is 3.715. You don't need CIP length mags for 338 lapua. Here is a regular length mag for 338L.

https://mdttac.com/338lm-mdt-metal-magazine/

 

[45-90]

I used the same chassis for 300 WM & 338 Lapua. Just get the MDT 338 mag 3.715" OR the MDT300 WM 3.715"
Change bolts and barrels done...make it a switch barrel.
I run my 300 WM at 3.7" with match bullets, so 230grs can get to 2965 fps, or 200 SMK at 3150 fps in 26" barrel.

Some chassis will take the 3.85" MDT mags, so check those out if running long match bullets.
Flawless change out, or change back, 300 to 338...or in my case 510 whisper, based off the 338 Lapua.
Same reciever, different barrel, different bolt, different mag....cartridges the same length 3.715" mags.

 

[Terry Cross]

The standard length long AI mag is 3.715. You don't need CIP length mags for 338 lapua. Here is a regular length mag for 338L.

https://mdttac.com/338lm-mdt-metal-magazine/

A lot of factory .338LM offerings are now too long OAL to fit in the older SAAMI length .338LM mags.

If he is reloading, he will be fine with the shorter mags.

He should also pay attention to what chamber he plans on running. If his barrel is going to have the original SAAMI chamber with shorter leade and he decides to go with a stock and mag for CIP then proceeds to shoot CIP length ammo, he could run into pressure problems pretty quick, could have issues chambering a round and could also have issues pulling the bullet from a loaded round if he attempted to unchamber a loaded round.

 

[Aftermath]

I'm not sure why you want to convert shit. Just get what you need for intended use...

R700 AICS AT Chassis 300WM to 308Win conversion possible?

Hey All, I’m new here and new to this type of build, I’ve been trying to do research on possibly doing a multi caliber build on a AICS AT Chassis. But haven’t been able to find much and whatever information I could find wasn’t too helpful on the internet. I was hoping someone can guide me in...

www.snipershide.com

 

[Boyydavid]

I'm not sure why you want to convert shit. Just get what you need for intended use...

R700 AICS AT Chassis 300WM to 308Win conversion possible?

Hey All, I’m new here and new to this type of build, I’ve been trying to do research on possibly doing a multi caliber build on a AICS AT Chassis. But haven’t been able to find much and whatever information I could find wasn’t too helpful on the internet. I was hoping someone can guide me in...

www.snipershide.com

I’m going down a whole rabbit hole and figuring what I would rather do for current and future build.

 

[Boyydavid]

A lot of factory .338LM offerings are now too long OAL to fit in the older SAAMI length .338LM mags.

If he is reloading, he will be fine with the shorter mags.

He should also pay attention to what chamber he plans on running. If his barrel is going to have the original SAAMI chamber with shorter leade and he decides to go with a stock and mag for CIP then proceeds to shoot CIP length ammo, he could run into pressure problems pretty quick, could have issues chambering a round and could also have issues pulling the bullet from a loaded round if he attempted to unchamber a loaded round.

Thanks for the heads up, I will look into that while building!

 

[Boyydavid]

I used the same chassis for 300 WM & 338 Lapua. Just get the MDT 338 mag 3.715" OR the MDT300 WM 3.715"
Change bolts and barrels done...make it a switch barrel.
I run my 300 WM at 3.7" with match bullets, so 230grs can get to 2965 fps, or 200 SMK at 3150 fps in 26" barrel.

Some chassis will take the 3.85" MDT mags, so check those out if running long match bullets.
Flawless change out, or change back, 300 to 338...or in my case 510 whisper, based off the 338 Lapua.
Same reciever, different barrel, different bolt, different mag....cartridges the same length 3.715" mags.

Thanks for the explanation, I’m new to the whole chassis system, this helped a lot

 

[Wannashootit]

or in my case 510 whisper, based off the 338 Lapua.

I thought that was the .416 Rigby? Badass round. Didn't know it was ultra-super-secret until I tried to find reamer specs to build one.

 

[45-90]

I thought that was the .416 Rigby? Badass round. Didn't know it was ultra-super-secret until I tried to find reamer specs to build one.

The .416 Rigby, the 338 Lapua, 300 Norma mag, etc all have the same head diameter.
Back in the day the .416 Rigby case was necked down to .338, long before the 338 Lapua....a few Varmint Hunters Club members used it for LR varmints over 2000 yds, as the 308 Win held the record at 2200 yds for awhile...I went to the 50BMG for squirrels, as did others.
I have a 416 Rigby also.

The .510 whisper is an excellent round.
I have the reamer, chambered & built the rifle, gauges, and brass.
350 gr copper expanding bullets at 2450 fps with 4700 ft lbs.
Or 1002 gr sub at 1100 fps at the muzzle with 2000 ft/lbs at 1000 yds.
APIT start penetrating AR 500 armor at 1200 fps and at 1450 fps it tears up Armor plate.
The APIT bullets detonate at low velocity of 800 fps. Total plinking fun, bang at the muzzle and flash of light, & loud pop down at the target. Throws targets high in the sky.
Some 510 Whisper pics.
Just completed 700 cases.
AR 500 taking a beating.
increase the velocity more penetration occurs at 100 yds.
Super 350 gr producing 4700 ft/lbs
750 Amax test loads.
A couple of cases one can make .510 whisper out of...300 Norma mag 338 Lapua mag.
Anyone considering the .510 Whisper cartridge should build one...I have the 300 Blk, the 8.6 Blk, but they do not compare to tbe .510 Whisper, for down range energy.
With subs It only loses 180 fps from muzzle to 1000 yds and hits with 2000 ft/lbs at 1000 yds. With lathe turned 1002 gr bullets, wind drift and drop are doable...not like the other subs.
Get ya one...

 

[Boyydavid]

The .416 Rigby, the 338 Lapua, 300 Norma mag, etc all have the same head diameter.
Back in the day the .416 Rigby case was necked down to .338, long before the 338 Lapua....a few Varmint Hunters Club members used it for LR varmints over 2000 yds, as the 308 Win held the record at 2200 yds for awhile...I went to the 50BMG for squirrels, as did others.
I have a 416 Rigby also.

The .510 whisper is an excellent round.
I have the reamer, chambered & built the rifle, gauges, and brass.
350 gr copper expanding bullets at 2450 fps with 4700 ft lbs.
Or 1002 gr sub at 1100 fps at the muzzle with 2000 ft/lbs at 1000 yds.
APIT start penetrating AR 500 armor at 1200 fps and at 1450 fps it tears up Armor plate.
The APIT bullets detonate at low velocity of 800 fps. Total plinking fun, bang at the muzzle and flash of light, & loud pop down at the target. Throws targets high in the sky.
Some 510 Whisper pics.
Just completed 700 cases.
AR 500 taking a beating.
increase the velocity more penetration occurs at 100 yds.
Super 350 gr producing 4700 ft/lbs
750 Amax test loads.
A couple of cases one can make .510 whisper out of...300 Norma mag 338 Lapua mag.
Anyone considering the .510 Whisper cartridge should build one...I have the 300 Blk, the 8.6 Blk, but they do not compare to tbe .510 Whisper, for down range energy.
With subs It only loses 180 fps from muzzle to 1000 yds and hits with 2000 ft/lbs at 1000 yds. With lathe turned 1002 gr bullets, wind drift and drop are doable...not like the other subs.
Get ya one...

That looks like a monster of a round to shoot. Unfortunately for me, I won’t be able to do anything as cool as that because I live in communist California

 

[45-90]

That looks like a monster of a round to shoot. Unfortunately for me, I won’t be able to do anything as cool as that because I live in communist California

Yeah, that's too bad....one should not be limited when it comes to just having a little fun with our shooting endeavors.

 

[Wannashootit]

I have the reamer, chambered & built the rifle, gauges, and brass.

Well, dayum...
None of my business... when I tried to look into it, I was told Jones wouldn't provide any information on it- 100% proprietary. Emailed him and never got a response so I dropped it.

 

[45-90]

I ordered mine from PT&G and received it with in a week. Took longer for the 10 Twist .510 barrel special order a bit over 2 months, from McGowen, but I did order a 6.5 twist. 338 at the same time.

Here is the .510 Whisper reamer, used it to chamber the barrel, make a cartridge gauge, and headspace brass gauge.

You can have a 510 Whisper...fairy cheap if you can do the work, but any good gunsmith can chamber ya one.

 

[Wannashootit]

I ordered mine from PT&G and received it with in a week. Took longer for the 10 Twist .510 barrel special order a bit over 2 months, from McGowen, but I did order a 6.5 twist. 338 at the same time.

Here is the .510 Whisper reamer, used it to chamber the barrel, make a cartridge gauge, and headspace brass gauge.

You can have a 510 Whisper...fairy cheap if you can do the work, but any good gunsmith can chamber ya one.

Thanks. Didn't know the print was public.
Going to do some more research on the brass, quick search shows it's lathe turned (I'm a smith so no problem with build to brass).
No idea what I'd do with it suppressed, but it would be a decent anti-materiel rifle when the SHTF... and if I hit the Powerball I can go hunt elephant

Definitely something different.