M1 Garands in .30-06 and .308?

[USSF06]

Having spent much time learning about M14s, I hate to say I know next to nothing about M1 Garands.
If I were to buy one, I like the idea of having one that uses the same ammo as my M14. Can someone give me a quick rundown of why there are M1 Garands chambered in .308 and the advantages/disadvantages of .30-06 vs .308 in it?

[GBA]

When NATO went to 7.62x51, the Navy didn't want to spend the money to swap out their Garands for M-14s. So in order not to have an ammo problem, they decided to convert their Garands to the NATO cartridge. The first try was a chamber adapter to shorten the chamber on the existing 30.06 barrels. That didn't work out. Many of the chamber adapters simply extracted with the spent 7.62x51 (.308) brass. So they went ahead and had new, properly chambered, barrels manufactured, and rebarreled the rifles. There are also Navy presentation match rifles out there in the marketplace so chambered. Jim Adell is an expert on these pieces. Also, .308 barrels are available from the CMP or commercial sites, and the conversion is relatively easy.

As to the advantages/disadvantages, the biggest advantage of .308 over 30.06 is that it allows a shorter action rifle. I don't believe that the Garand's action can be shortened. Anything that .308 can do, 30.06 can do better, except work in a shorter action rifle. So, if you want to only have to work and reload with one cartridge, go with the .308. Otherwise.......

[Phil McGrath]

In a nutshell, the Navy was cheap and didn't want too buy new rifles that would see very little use. So the Navy was looking for a cheap way out, and save the tax payer some jingle at the same time. There is a Gov't report that is very easy too read and has some very good detailed info that all M1 guys interested in the 7.62mm Garand should read. Its the "Report Of Evaluation On Navy Conversion Of Rifle, U.S.Cal.30, M1 to Fire 7.62mm Ammunition By Modification To the Barrel" Springfield Armory 30 Oct 1964. You can find it on-line pretty easy and might take you a whole 15min too read.

[Jersey Devil]

Here's a link to the report via the CMP. I'll post this in the Reference Section as well.

http://thecmp.org/wp-content/uploads...sionReport.pdf

[Phil McGrath]

Here is the set up or trick question. Now look at Appendix C Charts I and II, how would you read this information and what is it telling you?

[USSF06]

Thanks for sharing the report!
I'll give it a read soon.

[GBA]

Here is the set up or trick question. Now look at Appendix C Charts I and II, how would you read this information and what is it telling you?

Looks like the M80 round is not what the M1 needs in order to operate properly. MVs are faster due to smaller case volume and maybe faster powder. But there is probably not as much gas being produced which leads to lower GC pressures and marginal bolt velocities. Is that what you were thinking. If so, very sharp to pick that up. I never would have noticed it if you hadn't asked about it.

[Phil McGrath]

Looks like the M80 round is not what the M1 needs in order to operate properly. MVs are faster due to smaller case volume and maybe faster powder. But there is probably not as much gas being produced which leads to lower GC pressures and marginal bolt velocities. Is that what you were thinking. If so, very sharp to pick that up. I never would have noticed it if you hadn't asked about it.

Your 98% there, there's enough pressure at the chamber but the case doesn't hold enough powder in reserve like the 30.06 case can too maintain the pressure curve so by the time the gas hits the port in the barrel its dropping off. The extra M/V isn't a side effect of the smaller case volume its the M1's extra barrel length. So what does that do in the real world for us? Well a smart reloader can take advantage and bump up his loads for some added M/V and really extend his accuracy range, or shoot a heavier bullet while using slower powders and still be within safe gas cylinder pressures and not worry about the op-rod.

[OldTrooper]

I have some experience shooting both the 30.06 and the .308 in completion; my last rifle was chambered for the .308 because by then there was no question it was much more accurate. In fact it is the only M1 rifle I still own having sold my collectables to younger collectors. For what it is worth I would suggest if you want an original military rifle go with the 30.06 unless you are able to find one of the valuable Navy 7.62mm Navy rifles. If accuracy is all you care about and in your case if shooting the same cartridge as your M14 is that important go with the .308.

To be fair I should add the 30.06's larger casing can be loaded to higher power levels; I think this is more important for hunting rifles that the M1 rifle, but just though I would add it.

Here is a link supporting my accuracy comments: http://www.snipercountry.com/Articles/AccuracyFacts.asp

[lapriester]

When NATO went to 7.62x51, the Navy didn't want to spend the money to swap out their Garands for M-14s. So in order not to have an ammo problem, they decided to convert their Garands to the NATO cartridge. The first try was a chamber adapter to shorten the chamber on the existing 30.06 barrels. That didn't work out. Many of the chamber adapters simply extracted with the spent 7.62x51 (.308) brass. So they went ahead and had new, properly chambered, barrels manufactured, and rebarreled the rifles. There are also Navy presentation match rifles out there in the marketplace so chambered. Jim Adell is an expert on these pieces. Also, .308 barrels are available from the CMP or commercial sites, and the conversion is relatively easy.

As to the advantages/disadvantages, the biggest advantage of .308 over 30.06 is that it allows a shorter action rifle. I don't believe that the Garand's action can be shortened. Anything that .308 can do, 30.06 can do better, except work in a shorter action rifle. So, if you want to only have to work and reload with one cartridge, go with the .308. Otherwise.......

Actually it was the lack of adequate M14 production numbers to supply both the Army's greater needs, the need to change to the NATO standard rifle cartridge and the multiple issues the M14's were having at the time. I doubt it had anything at all to do with being cheaper...if it really was cheaper at all in the long run. They needed 7.62 NATO small arms and there simply weren't enough to go around. So, they chose to convert.

Another advantage to the 308 is it's inherent better accuracy overall. Meaning that no, it isn't so that anything a 308 can do a 30-06 can do better. How many current sniper rifles do you see out there in the military, and in civilian use, are chambered in 30-06? There's a reason for that.

Here is an excellent write up on Navy conversions and why: https://www.americanrifleman.org/art...garand-rifles/

[lapriester]

I riles me sometimes that folks seem to always discuss function problems with 308 M1's and why. I have both a Criterion barreled 308 and a 7.63 NATO M1. Both function perfectly with all ammo I have run through the rifles. Reloads, M80, commercial, you name it. The 7.62 rifle is SO overgassed I believe I could reduce my reloads from the fairly mild load 42gr of 4064 to 35gr of 4064 and the rifle would still function reliably. M80, in both rifles, ejects hard and far. Now, if you take a worn M1 with barely in spec parts, plus rubbing contact points, and all you do is stick a 308 barrel on it and expect perfect function with any ammo your expectations are much too high. There certainly is less gas pulse from a 308 compared to 30-06 but, with in spec parts and proper fitting components, that don't restrict function, even an M1 barreled with a Criterion barrel (which has a marginal gas port size) will function with virtually any ammo you want to use in it. If you want to convert an M1 to 308, do it right. Use good parts and properly relieve wood to metal and metal to metal contact points to assure reliability. Even the "cheap" Navy had full rebuilds done on the rifles when they were converted or used rifles fresh out of rebuild.