M1a chambering

[bombdog]

So, when finish reaming the new barrel, assuming it isn't chrome lined, do i use a .308 or 7.62 reamer??? And with that in mind, are all the SAI M1a's whether loaded, nm, super match, or standard, chambered in .308???
Thanks in advance...
bombdog, out here...

[StockDoc]

.308 reamer/ and yes SAI uses .308 and it will also chamber 7.62. You can ream a chamber in 308 that will not chamber 7.62.

[nf1e]

.308 reamer/ and yes SAI uses .308 and it will also chamber 7.62. You can ream a chamber in 308 that will not chamber 7.62.

Not exactly so. Both .308 and 7.62 ammo are loaded using .308 Winchester dies so the ammo would be the same. When the difference between .308 and 7.62 are talked about, it is the chamber dimensions that are different, not the ammo.

[Major Tom]

I used to own a Divine Texas M1A back in the mid '70s. It would function fine with military surplus 7.62. Not so much with my reloads tho. My reloads, which were full length sized, would not fully chamber (about 3/16") requiering me to bump the op-rod handle some. I even bought some small base load dies, still same problem. Wish I still had that rifle.

[nf1e]

I used to own a Divine Texas M1A back in the mid '70s. It would function fine with military surplus 7.62. Not so much with my reloads tho. My reloads, which were full length sized, would not fully chamber (about 3/16") requiering me to bump the op-rod handle some. I even bought some small base load dies, still same problem. Wish I still had that rifle.

That would have been caused by long cartridge head-space. Common problem for re-loaders. I would almost bet that the rifle's chamber was very close to 1.630 to 1.631 and your loads were slightly longer. I have been reaming my chambers to 1.633 lately using Pacific Tool reamers and 7.62 Nato guages. The rifles will eat any Nato or .308 commercial ammo you throw at them. Accuracy has not been adversely effected.

[StockDoc]

Not exactly so. Both .308 and 7.62 ammo are loaded using .308 Winchester dies so the ammo would be the same. When the difference between .308 and 7.62 are talked about, it is the chamber dimensions that are different, not the ammo.

American eagle ammunition makes both 308 and 7.62 ammo. I have a couple of of rifles that will not chamber both, the 7.62 is a wee bit longer and will not chamber in my 308 bolt gun or in my M14. Both I reamed the chambers on.

[nf1e]

American eagle ammunition makes both 308 and 7.62 ammo. I have a couple of of rifles that will not chamber both, the 7.62 is a wee bit longer and will not chamber in my 308 bolt gun or in my M14. Both I reamed the chambers on.

And your chamber dimensions are? Generally speaking, ammo mfgs try to keep 7.62 ammo under 175 gr. and .308 hunting stuff is usually over that and not recommended in an M1A or M14 type rifle. Head-space on both should be the same unless their QC is out of line. I think you will find that the powder and projectiles are the main difference.

[StockDoc]

I used a Clymer Go gage to set the headspace. it measures 1.630" , the 7.62 nato is 1.6

The 308 used a 150 grain bullet will the 7.62 used a 147 grain bullet. the 147 would not chamber.

And when I reload I use a L E Wilson case gage to set the sizing die, which is also 1.630

[bombdog]

My M1a in question will chamber both the military m80's and civilian .308 equivalents fine, and with great accuracy... i just wondered which chamber the folks at SAI put on their rifles so when i rebarrel her i can still reload for her... i read the article on 303british.com about the different dimensions of the two chambers, and seems to me a feller could, possibly, get in a bind shooting the .308 in a 7.62 chamber and then reloading it???
Just thinkin out loud...
bombdog, out...

[StockDoc]

My M1a in question will chamber both the military m80's and civilian .308 equivalents fine, and with great accuracy... i just wondered which chamber the folks at SAI put on their rifles so when i rebarrel her i can still reload for her... i read the article on 303british.com about the different dimensions of the two chambers, and seems to me a feller could, possibly, get in a bind shooting the .308 in a 7.62 chamber and then reloading it???
Just thinkin out loud...
bombdog, out...

this is one of those topics that can cause quite a bit of discussion. Like I said I keep my reaming at the low end of 1.630

[nf1e]

this is one of those topics that can cause quite a bit of discussion. Like I said I keep my reaming at the low end of 1.630

There in lies a problem sir. 1.630 is a very tight head-space. It was thought at one time that might add to accuracy. Truth is 1.632 - 1.633 would be a much better head-space for your rifle if you intend to use commercial ammo. Your cartridge head-space should be .003 to .005 less than your chamber for proper function. If you are using solely hand-loads then you need to set your dies to head-space 1.625 to 1.627 and as long as your trim length is in the neighborhood of 2.00, you should be good to go. Interior neck lube is also recommended for bottle neck cartridges and a good cam over on your press helps. Not attempting to be anything but helpful. After 50 years of reloading, I have made all the mistakes myself and enjoy helping others.

[bombdog]

Again, thanks gents, all this information is swellin my pumpkin... This is what i call an information rich environment...
bombdog...

[Phil McGrath]

I used a Clymer Go gage to set the headspace. it measures 1.630" , the 7.62 nato is 1.6

The 308 used a 150 grain bullet will the 7.62 used a 147 grain bullet. the 147 would not chamber.

And when I reload I use a L E Wilson case gage to set the sizing die, which is also 1.630

I would have that H/S gauge checked Clymer and Forester don't have the best reputation. Something also isn't right I suspect the reamer, you should be able too seat a 175@2.82 without it sticking or pulling out of the case even with min headspace and if you can't load 147's@2.80 something is very wrong....



Like I said I keep my reaming at the low end of 1.630

That is on the tight side, and old school. 1.632-1.634 is about optimum, you do have too have some room for the case too expand

[StockDoc]

I would have that H/S gauge checked Clymer and Forester don't have the best reputation. Something also isn't right I suspect the reamer, you should be able too seat a 175@2.82 without it sticking or pulling out of the case even with min headspace and if you can't load 147's@2.80 something is very wrong....




That is on the tight side, and old school. 1.632-1.634 is about optimum, you do have too have some room for the case too expand

I'm not worried, the rifles shoot fine with the 308-150, have some 168 going to try, and they to chamber fine, just have not shot them yet.

[StockDoc]

There in lies a problem sir. 1.630 is a very tight head-space. It was thought at one time that might add to accuracy. Truth is 1.632 - 1.633 would be a much better head-space for your rifle if you intend to use commercial ammo. Your cartridge head-space should be .003 to .005 less than your chamber for proper function. If you are using solely hand-loads then you need to set your dies to head-space 1.625 to 1.627 and as long as your trim length is in the neighborhood of 2.00, you should be good to go. Interior neck lube is also recommended for bottle neck cartridges and a good cam over on your press helps. Not attempting to be anything but helpful. After 50 years of reloading, I have made all the mistakes myself and enjoy helping others.

I appreciate the info and will try it, thanks. One of these days I am just going to have to get a HS Micrometer to set the dies. Yeah, I am very old school on things. Thanks again