Running .308 rounds in a 7.62x51 NATO chamber

[HALODIN]

I hope I can get away with neck resizing, I'll find out next weekend!

What load do you put through your M14 and what accuracy (moa) do you get out of it?

that's one advantage to the straight pull conversion.
you can fire form.

i have to full size em each time.
and brass life is limited because the m14 's cycle is a bit rough on the brass.

M14forums says 3-4 times. i've managed 5 times and and no case separation yet.. though they are soft loads..

[HALODIN]

Good post Laurie, lots of useful information, thanks.

[Andy632]

What load do you put through your M14 and what accuracy (moa) do you get out of it?

My best load seems to be the 175gn Berger in a Lapua .308w case, in front of 42.0 gns of Varget and lit by a Federal 210 primer, giving a velocity from my rifle of approx. 2550 fps.
Yesterday it was shooting less than 1.0 moa at 500 yards.(using Harris bipod, no rear bag and it's a 4-5-14 x 40 scope.)

[HALODIN]

IIRC you imported your M14 is that right? If so... what make is it and do you know the twist rate of your barrel? That load is a long way from the ammo I tested today. 1 moa is nothing to be sniffed at for a battle rifle!

My best load seems to be the 175gn Berger in a Lapua .308w case, in front of 42.0 gns of Varget and lit by a Federal 210 primer, giving a velocity from my rifle of approx. 2550 fps.
Yesterday it was shooting less than 1.0 moa at 500 yards.(using Harris bipod, no rear bag and it's a 4-5-14 x 40 scope.)

[Andy632]

IIRC you imported your M14 is that right? If so... what make is it and do you know the twist rate of your barrel? That load is a long way from the ammo I tested today. 1 moa is nothing to be sniffed at for a battle rifle!

My best load seems to be the 175gn Berger in a Lapua .308w case, in front of 42.0 gns of Varget and lit by a Federal 210 primer, giving a velocity from my rifle of approx. 2550 fps.
Yesterday it was shooting less than 1.0 moa at 500 yards.(using Harris bipod, no rear bag and it's a 4-5-14 x 40 scope.)

Yes, it's basically a Fulton Armory, M14 Peerless National Match model with heavy contour 1 in 10 stainless/grey Krieger barrel.
Yesterday I was consistently hitting the marking disc on the Fig 11 target's head from the 500 yard point, got boring after a while!.

[HALODIN]

My LDT M14 is a 1:10 as well. I have some heavier rounds made up yet to test, I think they're 175gr, it will be interesting to compare the results with yours. Yes I can see how boring that would get...

Yes, it's basically a Fulton Armory, M14 Peerless National Match model with heavy contour 1 in 10 stainless/grey Krieger barrel.
Yesterday I was consistently hitting the marking disc on the Fig 11 target's head from the 500 yard point, got boring after a while!.

[tackb]

I've been running some tests and speaking to every man and his dog about this, but I'm curious if anyone can offer an explanation for this.

I've been advised the LDT-M14 was proofed at the Belgian proof house in Liege before delivery and is safe to shoot .308 as tested in Visier Magazine "Visier N°6...LuxDefTec M14 US Klassiker-Jetzt neu aus Luxembourg" (see pages 36-43)

There is part of the article here http://issuu.com/vsmedien/docs/visier_06_2013_leseprobe

1 (Good) to 7 (Bad)
147grs RWS Cineshot HP, .................................2
147grs Sellier & Bellot FMJ, .............................4
150grs Tulammo FMJ, ......................................7
155grs Hornady TAP FPD, ................................ 1 (5 shot group 1.9cm IIRC)
168grs RWS Target Elite HP-BT..........................6
168grs Sellier & Bellot HP-King M' King...........3
168grs Remington HP-BT M'King......................5

So it seems like it should be OK, however we downsized a .308 round from 62,000 PSI (.308) to 50,000 PSI (7.62x51 NATO) and 2 of the 3 test shots caused the primer to stand proud out of the back of the brass (see example pic below). I don't believe the brass was new and whilst I don't know very much about self loading yet, could case trimming have caused this? i.e. with new .308 commercial brass would this problem disappear?

Am I missing something but that picture is not of a 308?

[HALODIN]

No you're quite right, it was borrowed from this thread to help explain the situation. When I said "(see example pic below)" I didn't mean it was an example of my brass. I guess I should have used a .308 case to avoid confusion!

http://www.milsurps.com/showthread.php?t=24151&page=2

Am I missing something but that picture is not of a 308?

[HALODIN]

As promised. This was the target from last summer using GGG 7,62x51 in my LDT-M14 EBR, not very good I know...



Now this was from a casual plink through this morning's freezing fog with 168gr Hornady A-MAX and the target was just a 2.5" red circle with no central point of reference, so the results may be better under better conditions. I have to admit I was quite pleased with the results, considering this isn't really a target rifle. As I calculate it, .74 - .308 = 0.432 moa which is completely respectable IMO.



Whilst I've blamed everything under the sun for this rifle not performing as expected, the issue turned out to be the barrel-whip grub screw at the business end of the EBR chassis. The manufacturers claim it improves accuracy, but I've put hundreds of rounds through this rifle that confirms it doesn't. It took me nearly 6 months to realise this was the problem, but now it's backed out, it shoots lovely. I'm just pleased I can finally enjoy the rifle, it was getting further and further back in the gun cabinet...

I'm constantly working on my technique, that's what beginners do, but it was only to demonstrate a casual plink with milsurp GGG from a rifle that isn't setup properly yet. Given all of that, I still think 2 moa is OK. Mediocrity under adversity is still a positive IMO. I'll post another target once I've used a correct size rear bag, bedded it in properly, added a roll pin, adjusted the barrel tensioning grub screw and tried out some match .308 ammo, just so you know I'm not s***!