7.62 Nato / 308

L

lilguy

Guest
I bought a 40X, used, in the late 70's and tucked it away. Was told back then I could shoot 308 at the time but did not use it. Years later found out that factory 308's would not chamber, bolt would not close. The only way to close the action was to set the shoulder way back when reloading. Not exactly the way I learned to reload. Whats the Difference between the 7.62 and 308 and how do you load it without crushing the case to get them to chamber?
 
What information is stamped on the barrel as to cartridge or chamber specs?
A 7.62 Nato standard military chamber is usually bigger and more sloppy than a factory .308 Win chamber.
It could have a nato match chamber or it could have been shortened to a 308 1 & 1/2 .
It might not even be .308 win? If you are having that kind of problem then you really need to make a cast of the chamber and then measure your casting against the standard .308 win. That will tell you what is not right.
It may just need a new chamber cut .
 
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I guess your next action should be to measure the chamber. I would use Cerro-Safe and make a casting of the chamber and work with that.
 
Measure the chamber

It is prolly a tite neck...lots-0-folks shot that combo way bak....measure the neck...shuld find it to be somewhere around .330 +/- a lil...just a guess....Roger
 
A chamber cast is certainly the best route to take. But Roger is probably on to something. A quick way to determine that would be to FL size a case without the expander ball. That would result in a neck a lot skinnier than even a tight neck. If it chambers, then you proceed to the next step which is to actually measure the neck diameter.

Ray
 
There was a practice with Brit TR shooters to use short chambers when shooting NATO ammunition. That way, the lousy manufacture tolerances of the ammo could be evened out by l-e-v-e-r-i-n-g the chamber closed. Paticularly popular with the Brit RG ammunition which tended to being a tad banana shaped.

Maybe somebody used that logic.
 
I have a 40X stamped 7.62 Nato on the barrel. I bought it new in the early '70s. It fires GI and GI match ammo just fine. It fires Federal match ammo just fine. The rifle is all factory - including the barrel.
 
I think you need a trip to your local gunsmith to open up the chamber a bit and increase the headspace to neatly chamber your ammo.
I think someone has reduced the headspace excessivly at some point before you got it.
 
lilguy

I would not do anything to that rifle until I was certain of what I have. It would be a shame to ream it out only to find out later that it is one of only a few made, for whatever the reason.

JMHO

Ray
 
I would think that if it is stamped 7.62 Nato and it will not even chamber the .308 round then I cant see it having any extra intrinsic collector value over anyother 40x . If it was something special the Rem custom shop would have stated it on the barrel.
I think the owner wants to use it or he would not be trying to jam 308's in it.
 
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Either chamber cast it yourself or have a gunsmith do it. Also, contact remington and see what you can find out about the manufacture of the gun. Do not have a gunsmith just run in a reamer yet. If you do decide to adjust it to fire standard factory .308, the barrel will probably need set back a inch or two or you could end up with a stepped chamber and that is really bad. ALL REAMERS ARE NOT THE SAME. If you are planning to reload for it, then the tight chamber is no big deal anyway, just make sure of the neck size.

Hovis
 
7.62

lilguy, If your talking about loaded 7.62 rounds that will chamber. It might be the bullet is crimped in the cartridge so theyll feed better. The neck might be enough smaller it will start in the chamber. I assume the 40x has a tighter neck than a sporter you may have to neck turn. I ran millions of 7.62 at Lake City. Doug
 
Initally I wanted to use it for the club High Power Team. Ended up using a heavy barreled Mini 14. I was also ,at the time, reloading for a Ruger bolt action 308.Could not close bolt on the 40X using new or reloaded 308's.
I was going to try to find 7.62 ball ammo first to see if it chambers. The gun is totally setup for highpower, never really tested the weapons ability, I am getting interested again after 30+ years. Will contact Remington also.
 
Every 40X in .308 that I've seen is marked 7.62 NATO, and they will all chamber any .308 commercial or 7.62 military round if no change has been made. In fact, they have a fairly long throat, you need to seat a 168 at 2.890" to reach the lands on a new one.

Will a new piece of brass (no bullet) chamber?
 
For what it is worth

I looked up this information which may or may not be appropriate to this situation but here it is.
The USGI origional M14 rifles ran long in the hedspace typically around 1.638-1.641". The .308 commercial dimensions (1.630-1.636")
Hope this helps.
I realize this is not addressing the neck diameter.
Centerfire
 
Remington 40-X 7.62 NATO Reloading

Remington 40-X 7.62 NATO Reloading

Loaded 40 rounds using...
• Hornady 168 a-max bullets
• Federal Gold Medal brass
• IMR 4064 Powder
• Winchester primers (large rifle)
• Rock Chucker
• Redding Competition Dies (308)

Loaded the rounds per Sierra loading manual for 168 Matchking. However the rounds would not chamber into the Remington 40-X 7.62 NATO. After measuring the rounds and compared to ZQI 7.62x51/Perfecta 308 my Redding competition sizing dies (full length) did not size the last ¼” of the case length, causing the diameter to be too large.

• Measured reloaded rounds last ¼” case length = 0.470” (diameter) actual
• 7.62x51 chamber dimensions last ¼” case length = 0.4693” (diameter) max
• 308 Winchester chamber dimension last ¼” case length = 0.4705” (diameter) max

Checked my sizing die and the die was set to just over cam (shell holder and bottom of die touch and a bit more). Checked my RCSB die and it looks like I can size the full length of the case with this die (and maybe use7.62x51 cases). Will use these rounds in my TIKKA Master Sporter cambered in 308 Winchester for tomorrows mad minute match!
 
"" Was told back then I COULD shoot 308 at the time but did not use it.""

First things first. Bring it to a Gunsmith and have him check the chamber with a (Go-No Go gauge) You will have your answer.
 
VOR503SM said:
Remington 40-X 7.62 NATO Reloading

Loaded 40 rounds using...
• Hornady 168 a-max bullets
• Federal Gold Medal brass
• IMR 4064 Powder
• Winchester primers (large rifle)
• Rock Chucker
• Redding Competition Dies (308)

Loaded the rounds per Sierra loading manual for 168 Matchking. However the rounds would not chamber into the Remington 40-X 7.62 NATO. After measuring the rounds and compared to ZQI 7.62x51/Perfecta 308 my Redding competition sizing dies (full length) did not size the last ¼” of the case length, causing the diameter to be too large.

• Measured reloaded rounds last ¼” case length = 0.470” (diameter) actual
• 7.62x51 chamber dimensions last ¼” case length = 0.4693” (diameter) max
• 308 Winchester chamber dimension last ¼” case length = 0.4705” (diameter) max

Checked my sizing die and the die was set to just over cam (shell holder and bottom of die touch and a bit more). Checked my RCSB die and it looks like I can size the full length of the case with this die (and maybe use7.62x51 cases). Will use these rounds in my TIKKA Master Sporter cambered in 308 Winchester for tomorrows mad minute match!
Click to expand...


I don't think your die is the problem.
I would check your COL and make sure the bullet is not jamming tight in the leade. Sierra lists their load data with the COL at SAAMI max for the cartridge and not all bullets work at this length in every chamber.
just my $0.02
 
7.62mm/.308 Headspace Comparison

If you want a little more confusion on the proper headspace, this is what we have compiled from various drawings and gages thru the years.
 

Attachments

  • 7.62mm-.308 HS Comparison.docx
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