Reloading 7.62 Nato?...

[oneshot onekill]

I know this topic has been beaten to death and I thought (until now) that I knew the skinny... Apparently not!
There's a post in the Bolt Action Rifle section about a Savage 10FCP. It's regarding 7.62 Nato vs .308. AXEMAN posted a link to an article that I found VERY interesting...

Here's my "question" if you will: I have a 40X chambered in 7.62 Nato. I've been having a hell of a time with over-pressure signs, brass sizing, etc. I've been using load data and dies for .308. Should I be using 7.62 Nato Dies? And if so, Where do you get them? Should I also be using different Load Data? The books I have ONLY have Data on .308... Nothing for 7.62 Nato.

I've been led to believe the two calibers were, for the most part, interchangeable... Even from posts I've read right here on the Hide. I have also read that shooting .308 in a 7.62 Nato rifle was fine but shooting 7.62 Nato in a .308 could be dangerous. The above mentioned article states the opposite!

So now I'm thoroughly confused and looking to the Guru's here to set me straight!

As always, thanks in advance!

John

 

[kraigWY]

Re: Reloading 7.62 Nato?...

Get any diecent set of 308 dies, FL work, then get a case gage, wilson, dillon, etc to make sure the sized brass is to specs. Use the case gage to set up your sizing die.

Then load the round according to any reloading manual,

If that bullet dosnt work in your gun, then its the gun not the ammo.

 

[oneshot onekill]

Re: Reloading 7.62 Nato?...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kraigWY</div><div class="ubbcode-body">Get any diecent set of 308 dies, FL work, then get a case gage, wilson, dillon, etc to make sure the sized brass is to specs. Use the case gage to set up your sizing die.

Then load the round according to any reloading manual,

If that bullet dosnt work in your gun, then its the gun not the ammo. </div></div>
Well that's exactly what I've been most recently doing but I haven't tested those bullets yet. I sized the brass to my chamber by removing the firing pin assembly from the bolt and bumping the shoulders until there was very, very slight tension lowering the bolt-handle. Then I checked it with the Case Length Gauge and it IS within tolerance. I'm only asking because the Case Length Gauge is .308... Not 7.62 Nato.

So it looks like I'm GTG.

Thanks,
John

 

[MitchAlsup]

Re: Reloading 7.62 Nato?...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: oneshot onekill</div><div class="ubbcode-body">I have a 40X chambered in 7.62 Nato. I've been having a hell of a time with over-pressure signs, brass sizing, etc. I've been using load data and dies for .308. Should I be using 7.62 Nato Dies? And if so, </div></div>

Any 308 die can be adjusted to produce 7.62 NATO sized cases (NATO is slightly longer).

As for pressure signs: lower the charge weight until this goes away; start by taking 1 full grain away, and work down from there.

7.62*51 cases will be heavier than comercial 308 and therefore use less powder for the same pressures. 308 cases, fire formed in your chamber should be just fine--when loaded to reasonable pressures.

Here's the reamer spec's for both:

.308 Win commercial
Shank 0.4370
Base Diameter 0.4700
Shoulder Diameter 0.4550
Neck-1 0.3462
Neck-2/Case Mouth 0.3442
Freebore Diameter 0.3100
Pilot Diameter 0.2990
Min. Chamber Length/Base-to-Case Mouth 2.0250
Base-to-Shoulder 1.3540
Neck Length 0.3210
Freebore Length 0.0900
Rim/Belt Thickness 0.2000
Shoulder Angle 20*
Throat 1*45”

7.62 NATO
Shank 0.4670
Base Diameter 0.4725
Shoulder Diameter 0.4560
Neck-1 0.3460
Neck-2/Case Mouth 0.3460
Freebore Diameter 0.3110
Pilot Diameter 0.2990
Min. Chamber Length/Base-to-Case Mouth 2.0250
Base-to-Shoulder 1.3560
Neck Length 0.3200
Freebore Length 0.1500
Rim/Belt Thickness 0.2000
Shoulder Angle 20*
Throat 2.5*

 

[oneshot onekill]

Re: Reloading 7.62 Nato?...

Great info MitchAlsup! Thank you! I have a fair amount of Lake City Brass that was "once-fired" in various rifles I've owned over the years. I'll probably ONLY use that brass from now on... until it's worn out. I plan to FL size it, fire it, and then start neck-sizing from there. I do back the charge down in that brass because it has noticeably less internal volume then the .308 commercial brass I've used.

Thanks again!

John

 

[ChrisGarrett]

Re: Reloading 7.62 Nato?...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: oneshot onekill</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kraigWY</div><div class="ubbcode-body">Get any diecent set of 308 dies, FL work, then get a case gage, wilson, dillon, etc to make sure the sized brass is to specs. Use the case gage to set up your sizing die.

Then load the round according to any reloading manual,

If that bullet dosnt work in your gun, then its the gun not the ammo. </div></div>
Well that's exactly what I've been most recently doing but I haven't tested those bullets yet. I sized the brass to my chamber by removing the firing pin assembly from the bolt and bumping the shoulders until there was very, very slight tension lowering the bolt-handle. Then I checked it with the Case Length Gauge and it IS within tolerance. I'm only asking because the Case Length Gauge is .308... Not 7.62 Nato.

So it looks like I'm GTG.

Thanks,
John </div></div>

Dimensionally, they're pretty much the same. There are no dies labeled 7.62x51 NATO, much like there aren't dies labeled 5.56x45 NATO. There can be hot 308 Winchester loads that can get close to exceeding NATO 7.62 chamber specs, but it's almost negligible, unlike shooting 5.56x45 NATO rounds in a 223 chamber, where SAAMI has issued a 'technical bulletin' stating that it is dangerous.


Get yourself some headspace gages if you're running a tight chamber, be it 308 Win or a true 7.62 chamber and start low, working up. You need to also get yourself an OAL gage and modified case to see where your lands are for a particular bullet.

Otherwise, it should be pretty easy.

Chris

 

[oneshot onekill]

Re: Reloading 7.62 Nato?...

Thanks Chris!

The education continues...

 

[michaeltx]

Re: Reloading 7.62 Nato?...

The 7.62 nato spec has a lower pressure than the saami 308 win spec. It's the opposite of the 223 vs. 5.56 situation. Your rifle might have a shorter throat than a normal commercial 308 win rifle, that could be the source of your early high pressure signs. Like CG said above, you've got the find out where the rifling starts.

 

[Country]

Re: Reloading 7.62 Nato?...

No Military chambers usually have longer free bores than commercial chambers.
Pressure can rise a bit using military brass in a tighter 308 W standard chamber. The internal volume in the military brass is less and you size it down a bit more to get it in reducing it even more. So as stated above start with 308 W load data and reduce the load down and then work back up to a safe good working load.

 

[Niles Coyote]

Re: Reloading 7.62 Nato?...

If it helps, this is what I have found in my 308 with a match chamber.

Using Winchester brass, my accuracy load with a 175 smk is 45 grains of Varget, with Lapua brass it is 44.6 and with Lake City 91 it is 43.3 grains. All share almost the same velocity with in 20 fps of each other.

When I loaded a few of the LC 91 to test different charge weights I stopped at 44.4 because I was already 40 fps over my hottest Winchester load and was beginning to show pressure signs.