Spacers and rear site cover I added. Spacers not needed, but it does not allow 30-06 to be inserted at all! Spacers from CMP. metal ones are available but for double the price. Ste cover came from sleezebay. https://imgur.com/a/Tcb2pqM 

 

The Navy rifles are designed for 7.62 ONLY!! NO 308. at all.

Did you try a 7.62x51 or a .308 round? It might like that better.

Why would you be trying to seat a 30-06 round in a gun chambered for 7.62/.308Win?

I wouldn't, Just for anybody else that might use it after my demise!! M1 Garands are usually chambered for 30-06, some newer ones are changed to 308. But, these Navy were chambered for 7.62. All I shoot is 7.62 NATO. Mostly  use milsurp.

Understanding the Difference Between 7.62×51 and 308 Winchester  Before we delve much further, I must address this often-posed question “Are the7.62×51 NATO and .308 Winchester the same?”  Again, the answer is NO.  It is because of the differences in maximum pressures and the chamber specs. Nobody makes a 7.62mm (NATO) ammo that is not fitting to the .308 ‘headspace’ dimension spec. As a rule, this makes the 7.62mm ammo fit into .308 chambers.  But if you go the other way, you can encounter problems.  A commercial .308 Winchester round exceeds the maximum rated pressure for the 7.62×51 ammo. If this is the case, avoid putting full-power .308 Win rounds into military rifles designed for a maximum pressure of 50,000 psi. This text is originally from HuntingHeart.com, you can read more here: https://huntingheart.com/can-you-shoot-a-7-62-x-51-ammo-in-a-308-rifle/

1 hour ago, 15636215 said:

I wouldn't, Just for anybody else that might use it after my demise!! M1 Garands are usually chambered for 30-06, some newer ones are changed to 308. But, these Navy were chambered for 7.62. All I shoot is 7.62 NATO. Mostly  use milsurp.

I guess I just didn't understand the purpose of the spacers. Do they prevent you even getting close to chambering a 30-06 in a 7.62 M1?

19 minutes ago, Mr.Stu said:

I guess I just didn't understand the purpose of the spacers. Do they prevent you even getting close to chambering a 30-06 in a 7.62 M1?

Yes, Spacer not really needed, but with it in place, there is no way to get 30-06 in.   They did make 2 types of conversion. The first style they inserted a liner in barrel that really did not work. Then they decided to change barrels and gas port for 7.62. AMF and H&R made the barrels. Mine are both H&R.