M305 Ammo .308 or 7.62x51

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atticus

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So I tried searching for an answer as I'm sure I'm not the first to ask this question, but no dice.

I'm looking to pick up a M14 shorty pretty soon and was looking into the price of ammo at my local store.

I saw CanAm sells a combo of gun + .308 ammo.

Now I'm not sure where I have this from, but I was under the impression that the M305 shoots 7.62x51 NATO? Is that an assumption that's completely out of left field or is there something to it? Did I maybe read about people shooting 7.62 rounds with it?

The two cartridges are fairly similar but surely there'd be an issue with headspace, no?
 
I believe it is stamped .308 Winchester on the receiver, which means it 'should' be able to shoot both higher pressure .308 Win and 7.62x51 NATO. If it is stamped 7.62x51 NATO, then you aren't 'supposed' to shoot higher pressure .308 Win.

However, because it's made in China, being stamped one way doesn't mean it can shoot the other.

Let the experts chime in.
 
mosinmaster said:
I believe it is stamped .308 Winchester on the receiver, which means it 'should' be able to shoot both higher pressure .308 Win and 7.62x51 NATO. If it is stamped 7.62x51 NATO, then you aren't 'supposed' to shoot higher pressure .308 Win.

However, because it's made in China, being stamped one way doesn't mean it can shoot the other.

Let the experts chime in.
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It has nothing to do with pressure, but rather the differing headspace requirements IIRC.
 
.30/06 FTW said:
It has nothing to do with pressure, but rather the differing headspace requirements IIRC.
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I realize this. While doing a little google search online before posting here I saw some people say that firing 7.62 in a rifle meant for .308 is 'usually' doable, but vice versa is not.

this is the explanation I found

If a firearms is chambered to the 7.62 NATO spec, it is absolutely unsafe to fire .308 Winchester for the same reasons that you wouldn't shoot a rifle that was shot so loose that it could swallow a NO-GO gauge with room to rattle: Excessive headspace allows cartridge brass to flow too far forward under pressure, potentially stretching at the web to the point that the case ruptures, causing an explosion.

7.62x51mm chambers get away with being so loose because 7.62 ammo is made thicker at the base than .308. The extra brass provides enough material to prevent ruptures, and is the reason why most reloading manuals advise downloading by about 10% when using military brass. Conversely, thinner .308 brass provides more case room, but less leeway in chamber dimensions.
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That being said, everyone on the internet has their own answer and usually never has any documents or sources to back them up, which is why I thought I'd start this discussion here to see what you guys think/do.
 
I'd say shoot either in your chinese m14. Tolerances weren't so tight that you could pin down which of the two it was really made for. Choose the one that shoots the best, and avoid heavy weight 308 ammo like the 180's.
 
we use the cb 40 gage on c 6 machine guns in 7.62 x 51. on a m305 when you use the gage i can push the bolt forward a c*nt hair. they are loose. i wouldent own a m 305 if you paid me. i think they are sloppy.
 
Grizzlypeg said:
I'd say shoot either in your chinese m14. Tolerances weren't so tight that you could pin down which of the two it was really made for. Choose the one that shoots the best, and avoid heavy weight 308 ammo like the 180's.
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Really? I only shoot .308 180 grain as my m305 is my main black bear and moose rifle
 
somebody needs to read the "cautions" on using a heavy weight( 180 grains) as a steady diet in the m14 platform- you'll get away with it temporarily , but there's a reason why the recommended top end is 175 grains- also commercial 308/180s travel at 2610 or better- m118 is 175 gr smks at 2550- ie it's a bit overloaded for the m14, even disregarding the weight issue
 
Iron sights said:
Really? I only shoot .308 180 grain as my m305 is my main black bear and moose rifle
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How many rounds of 180 have you put through your rifle? I'm going on the advice that 180's put too much load on the op rod and lead to premature wear or bending of it. I'm not sure exactly how it works, but somehow the 180's result in higher pressure in the gas system, resulting in more force on the oprod during the bolt opening cycle.
 
it's fairly well explained in the GARAND notes- just the same as using a powder with the WRONG PRESSURE CURVE in the garand-
 
Grizzlypeg said:
How many rounds of 180 have you put through your rifle? I'm going on the advice that 180's put too much load on the op rod and lead to premature wear or bending of it. I'm not sure exactly how it works, but somehow the 180's result in higher pressure in the gas system, resulting in more force on the oprod during the bolt opening cycle.
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34 rounds
 
Iron sights said:
34 rounds
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I was hoping you were going to help dispel the whole notion by saying you've shot a thousand 180gr through your gun. I don't think anyone can say this number is ok and this number of shots isn't. It's clear from your experience and others I've seen at the range, that shooting a couple of boxes of 180's doesn't result in (immediate) op rod failure. Personally, if I had need to shoot a few 180's, I'd just keep the number low, and watch for bending or abnormal wear of the oprod. You could limit the wear and tear during re-sighting in by turning the gas system off. Just remember to turn it back on when you go hunting.
 
Boum13 said:
The SAAMI find that for a rifle chamber for a 308 not to use 7.62x39, 300 Savage but nothing on 7.62 NATO.
http://www.saami.org/specifications...1-Unsafe_Arms_and_Ammunition_Combinations.pdf

But the M305 is it chamber for a 308 or 7.62 NATO?

the marking on my rifle are 308 but with made in China
Did they keep the spec of the M14?
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only a MORON would use 7.62x39 or 300 savage in a 308 winchester chamber anyway- one's the WRONG BORE DIAMETER( 7,62x39 is really .311 ) OR the case is too short- in BOTH cases- now as to your other question,
yes, it is a TRUE 7.62x51 chamber- you slip a 308 go/nogo guage in there and it'll swallow it due to the longer neck- but it is TOLERABLE-ie close enough- that's why the MAJORITY of guys have been using 308/150 grain rounds
 
t-star said:
only a MORON would use 7.62x39 or 300 savage in a 308 winchester chamber anyway- one's the WRONG BORE DIAMETER( 7,62x39 is really .311 ) OR the case is too short- in BOTH cases- now as to your other question,
yes, it is a TRUE 7.62x51 chamber- you slip a 308 go/nogo guage in there and it'll swallow it due to the longer neck- but it is TOLERABLE-ie close enough- that's why the MAJORITY of guys have been using 308/150 grain rounds
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or they can not read,

I fired both 180 and 150 grains from Winchester (under 40 rounds)

the spend brass lips had 1/8 inch powder residue for the 180 grains
and 1/16 inch for 150 grains

Is it have something to do with the pressure?

Also 150 grain seem a little more accurate but I have not shot much
 
at 40 rounds you're not going to see ANYTHING- what i'm talking about is a couple of THOUSAND - what happens is that you get microfractures from the piston hitting the op-rod too hard and the op-rod breaking at the welds or bending- with the chinese it's a one piece op-rod with no welds, so it tolerates the abuse a little better than the old usgi welded ones-it's not the pressure , but the PRESSURE CURVE generated by the load ( ie it "slaps" the op-rod too hard) and breaks the welds or joints - however, you can get replacement op-rods
now , from what they tell me SADLAK makes a special piston that's designed for 175's and better, and if you absolutely have to have 180s this is the way to go- however, there's an awful lot of us that have learned to shoot 165-168 grains and get it done with NO APPRECIABLE WEAR on the oprod etc- i know, the m14 was designed around the 147 grain nato load, but just b/c it's nato spec doesn't mean it's the best load for accuracy- i have 4 and they all like the 165-168 series- you need to read the zediker article on the net
 
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