Moving to 308 Winchester or 7.62x51mm

[rsilvers]

I have many FALs, and M14s, and M1As - and my complaint with the FAL is that the stock has too much drop to shoot it with optics - and I have not found a cheek piece that is non-cheesy.

I would get the SCAR, but if you want to rule it out over not taking PMags, then get the LaRue - I would prefer the lighter PredatAR version.

Really you should just keep the FAL and get the trigger converted to a lighter pull. DSA can do it on their rifles. Personally I never was unhappy with any of my FAL triggers.

As for 7.62 compared to 308 brass - there are differences in the brass requirements, but not so much the chamber - except for throat length - but why does that matter for battle rifle? I don't think one needs to put much thought into 7.62 vs 308.

[duece71]

I have had my M1A for 10 years now.....no scope, not planning on it. I bought an LMT and never looked back.....NF 2.5X10X32 for it when it finally arrives.

[jonconsiglio]

The more I shoot my SCAR H, the more I appreciate it. I've owned others as well, but this things runs hard and nothing stops it. It's quite accurate for what it is, and more can probably be squeezed out of it eventually.

Yes, mags are expensive and hard to find, but all you need to do is find one good deal and stock up. I don't run my Heavy the same way I run my Light or my ARs, so I don't see parts replacement being AS big of a deal with the Heavy.

If I was doing it over again, I'd probably now look at the PredatAR, but I don't think it has any serious advantage over the SCAR in terms of weight or accuracy. Personally, I think I'm cutting the barrel down to 13" and suppressing it with a Surefire mini 7.62.

I have about 500 total between the LMT MWS and the KAC SR25. While I like the SR25 for what it is and how it handles, it's just not for me, especially at those prices. The LMT is a nice system but it's heavy and there are times where I'm walking and carrying my rifles for days at a time and that extra 2 pounds is huge for my needs.

It's hard not to recommend the 7.62 PredatAR at an MSRP of $2,500 and under 8 pounds. I don't know what LaRue's accuracy guarantee is, but I'm sure it's pretty good. I imagine I'll most likely end up with one at some point. I have a number of bolt guns to get sub MOA accuracy, so personally, I'm willing to give up a half to 1 MOA in the accuracy department.

Just my experiences, but I really like the SCAR and think it's a great option as well as the PredatAR.

[Littlelebowski]

Dude, ask Chad about his LaRue PredatAR. It's got his seal of approval for this application.

[turdbocharged]

I had a 308 that I built off of the SR25/DPMS pattern, it functioned great but was heavy as a pig. So I sold it. They are also too expensive for my taste unless your reloading or using surplus ammo. Get something light, or just get a different upper 6.8,300B. That seems to be the best bang for your buck imo.

[shootist~]

However, the 0.013" chamber length difference does matter for reloading.

Based on a Google search, I'm assuming your data came from here?:
http://www.303british.com/id36.html

He is comparing a 7.62 1.632" No-Go Gauge to (someone's) Military 7.62 Field gauge at 1.645". This has nothing to do with chamber dimensions. It's just minimum spec vs maximum.

Who cares what the maximum field failure dimension is? (Well I guess it could matter if you are running thinner .308 in a worn or improperly headspaced rifle). By the way, military specs vary from country to country.

Headspace your FAL at or between 1.630" (SAAMI .308 "Go" gauge) and 1.6315' (FN's 7.62 Go gauge spec) and it will be more than tight enough for any .308, and will run in-spec NATO 7.62 just fine. It might be a little more accurate as well.

I built a bunch of FALs back when...and used 1.630 and 1.632 gauges. The 1.632 was my own personal No-Go gauge. FYI - SAAMI's .308 No-Go is 1.636" and FN's (7.62) No-Go is 1.638". (From memory here so look it up on the FALFiles if it matters.)

FALs can be accurized by getting the upper/lower fit tight (front and rear). The South African method was to shorten the hinge pin (easy and it works). If you have a worn out lower that's loose at the rear, you may be SOL or in need of replacing it with something better.

Triggers can be lightened, although the best (IMO) after market HTS kits are no longer available. Mine have pulls of ~4 lbs or less with full power hammer springs and shoot better than the SCAR-17 I've played with - so far, anyway.

[230therapy]

Dude, ask Chad about his LaRue PredatAR. It's got his seal of approval for this application.

Did Chad review his LaRue at the Bacon forum?

[230therapy]

Based on a Google search, I'm assuming your data came from here?:
http://www.303british.com/id36.html

He is comparing a 7.62 1.632" No-Go Gauge to (someone's) Military 7.62 Field gauge at 1.645". This has nothing to do with chamber dimensions. It's just minimum spec vs maximum.

Who cares what the maximum field failure dimension is? (Well I guess it could matter if you are running thinner .308 in a worn or improperly headspaced rifle). By the way, military specs vary from country to country.

Headspace your FAL at or between 1.630" (SAAMI .308 "Go" gauge) and 1.6315' (FN's 7.62 Go gauge spec) and it will be more than tight enough for any .308, and will run in-spec NATO 7.62 just fine. It might be a little more accurate as well.

I built a bunch of FALs back when...and used 1.630 and 1.632 gauges. The 1.632 was my own personal No-Go gauge. FYI - SAAMI's .308 No-Go is 1.636" and FN's (7.62) No-Go is 1.638". (From memory here so look it up on the FALFiles if it matters.)

FALs can be accurized by getting the upper/lower fit tight (front and rear). The South African method was to shorten the hinge pin (easy and it works). If you have a worn out lower that's loose at the rear, you may be SOL or in need of replacing it with something better.

Triggers can be lightened, although the best (IMO) after market HTS kits are no longer available. Mine have pulls of ~4 lbs or less with full power hammer springs and shoot better than the SCAR-17 I've played with - so far, anyway.

So this is wrong then:

There is a .013" difference in chamber length however, between these two "Safe & Serviceable" rifles!

It certainly looks like there's a difference in length from the graphic.

Therefore, what are the actual chamber dimensions of the 308 Winchester and 7.62x51mm? (digging around google a bit).

Reading this: http://carnival.saysuncle.com/002453.html

[shootist~]

He is stating the difference is .013" between a rifle with minimum HS and another that is at military Field (failure spec), and over the field spec by FN's max, btw. That part is true, but it has nothing to do with .308 vs 7.62 chambers.

[230therapy]

Let's look at the Says Uncle link. It has a much better explanation.

This is what I was thinking (though without the actual numbers):

If their 7.62x51mm NATO chamber is towards the minimum safe headspace (1.6355") then a .308 Winchester cartridge that measures 1.630" will result in .0055" of free space that the cartridge must stretch to fill.
For comparison a .308 Winchester chamber that measures 1.6355" (No Go dimension -.0005") will leave .0055" of room for a 1.630" cartridge. It'll still be safe to fire but will start to show a decrease in accuracy as well as a shortening of brass life.

Now the thing about chamber headspace is that it isn't a permanent dimension. Over time headspace will increase as the chamber is worn through normal use. After a few thousand rounds that 7.62x51mm NATO chamber that was at 1.6355" may very well be at 1.6375" which would be pushing what SAAMI considers the maximum allowable room between a cartridge & a chamber in .308 Winchester. When it gets to that point you're looking at .0075" of space that the cartridge must stretch to fill & you will notice a decrease in brass life.

And:

Now that you have a basic understanding of headspace gauges, let's look at some numbers:

7.62x51mm NATO Go 1.6355"
7.62x51mm NATO Field Reject 1.6455"

.308 Winchester Go 1.630"
.308 Winchester No Go 1.634"
.308 Winchester Field Reject 1.638"

7.62x51mm NATO minimum cartridge headspace 1.630
7.62x51mm NATO maximum cartridge headspace 1.633
7.62x51mm NATO average cartridge headspace 1.6315

.308 Winchester minimum cartridge headspace 1.627
.308 Winchester maximum cartridge headspace 1.633
.308 Winchester average cartridge headspace 1.630

As you can see there's a notable difference between the headspace of the .308 Winchester & the 7.62x51mm NATO chambers. To put it in a more direct contrast:

7.62x51mm NATO Go 1.6355"
.308 Winchester Go 1.630"

That's a difference of .0055"

7.62x51mm NATO Field Reject 1.6455"
.308 Winchester Field Reject 1.638"

That's a difference of .0075"

Now you might be thinking that .0075" is no big deal & certainly not .0055". Here's why it is a big deal:

The headspace tolerance for the .308 Winchester is .008" from minimum to maximum. SAAMI feels that if your chamber is .008" over the minimum then you'll have too much headspace to safely fire a cartridge. The problems of excessive headspace vary with the severity of the excess from reduced accuracy & short case life to case head separations & even self disassembly (a polite way of saying that you'll blow your firearm up). .008" is deemed to be too much of a safety risk & any gunsmith that finds that much headspace in a .308 Winchester will tell you not to fire your rifle until the headspace is corrected. But keep in mind this is just the difference in chamber headspace between the two.

Just seems different enough that it could be a problem after awhile. It seems like I should just get a 7.62x51mm chambered rifle and reload 7.62x51 brass. If I decide to shoot 308 Winchester out of it, just check headspace and make sure it's not past 0.008".

It also looks like manufacturers ream out enough of the 7.62x51mm's chamber to give 308 Winchester enough margin until wear occurs.