.308 in Win M70 .30-06

wileybelch · November 10, 2020, 01:16 AM

I want to change barrels on my .30-06 Win M70 to .308Win. Will the long .30-06 M70 receiver still feed .308Win ammo properly without further modification? Do you have to change/modify the follower to assure proper .308 feeding? What other issues involved with this change?

**Unclenick** · November 10, 2020, 03:51 PM

I imagine it will be alright. Some light bullet 30-06 loads aren't much longer than a full length .308 Win. See if you can borrow some factory new .308 and try to feed it; On paper, it is possible for .308 case shoulders to jam in a 30-06 chamber, but in practice, it doesn't usually happen with new brass due to tolerances making some extra space. Just feed the first one slowly while feeling for a bind and stop if you detect one. Also, don't try to fire it. It will fire safely, but the velocity won't be good and the brass you extract will be useless for reloading.

Scorch · November 10, 2020, 04:07 PM

Factory 308 M70s (before the short action's debut in the 1990s) used to have a spacer at the back of the magazine to hold the shells far enough forward to prevent tipping and nose diving when feeding from the longer magazine box. I have seen guns that had been rebarreled to 308 that worked fine. If it becomes an issue, you can buy a 308 magazine box.

Bart B. · November 10, 2020, 04:16 PM

You should replace the magazine and follower for 100% reliability.

Depending on the type, the bolt stop and extractor may need replaced.

Is it a control feed pre '64 action?

wileybelch · November 11, 2020, 09:28 PM

Bart
Why replace the box? I have both a pre-64 and push feed M70 under consideration. As far as I'm concerned, the extra long bolt throw to eject a .308 case is acceptable. I'm just concerned about reliable feeding. Single feeding seems OK. How about quick follow-up shots? Why would there be an extractor issue? Both cartridges have the same head? To me, the .308 cartridge coming off the follower sees the same barrel/chamber as the .30-06. Just wondering if someone has discovered a hidden flaw in this thinking - no theory, just facts, please.

Bart B. · November 11, 2020, 11:48 PM

308 cartridges are fatter than 30-06 cartridges and need a little more magazine width at the top.

Control feed 308 pre 64 extractors have a spacer on the clip so the bolt stop is positioned properly.

I learned this converting three pre 64 30-06 Model 70 rifles to 308 Winchester.

**44 AMP** · November 12, 2020, 02:54 AM

No theory, just some facts about a rifle I had...
In the early 70s I got a Mauser 98 in .308 Win.

Built by our local gunsmith Red Johnson, on a military Mauser action. Red put on a .308 Win barrel with Williams sights, a fairly rakish Fajen stock with a rollover cheekpiece and an agressively hooked pistol grip. Drilled and tapped and put on Weaver Tip-off mounts and a 3-9x scope.

Sold it to me for $140, generously allowing me $90 credit for the Winchester 190 I traded in. Him being friends with my dad, and a distant cousin might have had something to do with that, but that though never occurred to me until many years later.

No work other work was done to the action, nothing done to the rails, or the magazine, in fact, I hand to put the slope on the military follower so it wouldn't lock open empty.

I added a Numrich scope safety and a Jaeger trigger (couldn't get the Timney I wanted..)

That rifle functioned FLAWLESSLY. Fed EVERYTHING from 100gr plinkers to 220gr RNs. There was no block in the mag box, and, by today's standards it had a long throat. There was no "chasing the lands" on that gun. I could seat 180 RN to the full length of the mag box and they never hit the lands. What they did was allow for more powder in the .308 case and yes, I was running above listed book values.

Never an MOA rifle (in those days, damn little was) but a good solid 1.5-2MOA with any decent handload or factory ammo. Took deer just fine and a surprising number of woodchucks (with the 110jhp and 125 spitzer) at ranges 300 and under.

Main points, on THAT rifle, no alteration to the mag box, follower or extractor needed for feeding, it fed .308 flawlessly.

Another rifle might need more work, that one didn't and because of that I wouldn't automatically assume you HAD to do work on a .30-06 to get the .308 to run well in it, other than change the barrel.

Pathfinder45 · November 14, 2020, 06:17 PM

What's the matter with the 30-06 barrel that's on it? What do you hope to gain in this conversion?

November 10, 2020, 01:16 AM	#1
wileybelch Senior Member Join Date: May 16, 2009 Posts: 115	.308 in Win M70 .30-06 I want to change barrels on my .30-06 Win M70 to .308Win. Will the long .30-06 M70 receiver still feed .308Win ammo properly without further modification? Do you have to change/modify the follower to assure proper .308 feeding? What other issues involved with this change?

November 10, 2020, 03:51 PM	#2
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,061	I imagine it will be alright. Some light bullet 30-06 loads aren't much longer than a full length .308 Win. See if you can borrow some factory new .308 and try to feed it; On paper, it is possible for .308 case shoulders to jam in a 30-06 chamber, but in practice, it doesn't usually happen with new brass due to tolerances making some extra space. Just feed the first one slowly while feeling for a bind and stop if you detect one. Also, don't try to fire it. It will fire safely, but the velocity won't be good and the brass you extract will be useless for reloading. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

November 10, 2020, 04:07 PM	#3
Scorch Senior Member Join Date: February 13, 2006 Location: Washington state Posts: 15,248	Factory 308 M70s (before the short action's debut in the 1990s) used to have a spacer at the back of the magazine to hold the shells far enough forward to prevent tipping and nose diving when feeding from the longer magazine box. I have seen guns that had been rebarreled to 308 that worked fine. If it becomes an issue, you can buy a 308 magazine box. __________________ Never try to educate someone who resists knowledge at all costs. But what do I know? Summit Arms Services

November 12, 2020, 02:54 AM	#7
44 AMP Staff Join Date: March 11, 2006 Location: Upper US Posts: 28,820	No theory, just some facts about a rifle I had... In the early 70s I got a Mauser 98 in .308 Win. Built by our local gunsmith Red Johnson, on a military Mauser action. Red put on a .308 Win barrel with Williams sights, a fairly rakish Fajen stock with a rollover cheekpiece and an agressively hooked pistol grip. Drilled and tapped and put on Weaver Tip-off mounts and a 3-9x scope. Sold it to me for $140, generously allowing me $90 credit for the Winchester 190 I traded in. Him being friends with my dad, and a distant cousin might have had something to do with that, but that though never occurred to me until many years later. No work other work was done to the action, nothing done to the rails, or the magazine, in fact, I hand to put the slope on the military follower so it wouldn't lock open empty. I added a Numrich scope safety and a Jaeger trigger (couldn't get the Timney I wanted..) That rifle functioned FLAWLESSLY. Fed EVERYTHING from 100gr plinkers to 220gr RNs. There was no block in the mag box, and, by today's standards it had a long throat. There was no "chasing the lands" on that gun. I could seat 180 RN to the full length of the mag box and they never hit the lands. What they did was allow for more powder in the .308 case and yes, I was running above listed book values. Never an MOA rifle (in those days, damn little was) but a good solid 1.5-2MOA with any decent handload or factory ammo. Took deer just fine and a surprising number of woodchucks (with the 110jhp and 125 spitzer) at ranges 300 and under. Main points, on THAT rifle, no alteration to the mag box, follower or extractor needed for feeding, it fed .308 flawlessly. Another rifle might need more work, that one didn't and because of that I wouldn't automatically assume you HAD to do work on a .30-06 to get the .308 to run well in it, other than change the barrel. __________________ All else being equal (and it almost never is) bigger bullets tend to work better.

November 10, 2020, 04:16 PM	#4
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	You should replace the magazine and follower for 100% reliability. Depending on the type, the bolt stop and extractor may need replaced. Is it a control feed pre '64 action?

November 11, 2020, 09:28 PM	#5
wileybelch Senior Member Join Date: May 16, 2009 Posts: 115	Bart Why replace the box? I have both a pre-64 and push feed M70 under consideration. As far as I'm concerned, the extra long bolt throw to eject a .308 case is acceptable. I'm just concerned about reliable feeding. Single feeding seems OK. How about quick follow-up shots? Why would there be an extractor issue? Both cartridges have the same head? To me, the .308 cartridge coming off the follower sees the same barrel/chamber as the .30-06. Just wondering if someone has discovered a hidden flaw in this thinking - no theory, just facts, please.

November 11, 2020, 11:48 PM	#6
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	308 cartridges are fatter than 30-06 cartridges and need a little more magazine width at the top. Control feed 308 pre 64 extractors have a spacer on the clip so the bolt stop is positioned properly. I learned this converting three pre 64 30-06 Model 70 rifles to 308 Winchester.

November 14, 2020, 06:17 PM	#8
Pathfinder45 Senior Member Join Date: January 7, 2008 Posts: 3,224	What's the matter with the 30-06 barrel that's on it? What do you hope to gain in this conversion?