Thread: 7.62mm factory magazines - The L8 and L42 connection (by Peter Laidler)
Retrieved: 06/15/2014

7.62mm factory magazines - The L8 and L42 connection
(by Peter Laidler)

Someone asked a good question some weeks ago about these magazines and of the feed problems that you can encounter, even with a machined body as on the L42s. I was going to say L8s too but... Let's start with the L8s shall we?

It is my firm belief that when the L8 project first arose the designers considered that the c.1965 era L8, as proposed/converted, would be a relatively simple conversion and that the new magazine would fit without any machining. They pretty well state this as much. Mind you, the sales pitch and brochure was riddled with vagueness and what we'd call half truths now - but I digress. As a result, it's my considered opinion, after probably having seen more genuine ones than most, that the original genuine L8s weren't machined for the new magazine. Indeed, the 1969 damaged L8A2 body used for these photographs was totally unmodified. The reason being, as pointed out by Thunderbox and others, was that in truth, by selecting the actual body to be converted and maybe a little hand fitting or adjustment, the new magazine would fit and work, albeit after a bit of jiggery-pokery... But a bit of jiggery-pokery isn't good enough for a front line sniper rifle so come the conversion to L42 and in order to cure the or any 'problem' the magazine well was machined very slightly to accommodate this.

In essence, the machining was to VERY slightly chamfer the extreme outer edges at the inside rear of the magazine well in the body to cater for the slightly longer (.9" from .65") rear lip of the 7.62mm magazine. This was unnecessary. The next was to undercut rearwards the inside front of the magazine well to cater for the more rearward position of the front magazine lips. This time the undercut was extended rearwards from approx .5" to 1" to the same depth as the old recess. This clearance will positively allow the feed lips to be clear of the body. At the same time, the side walls of the magazine will sit on the left and right internal ledge of the magazine well.

Before we proceed, I want you to look at an old .303" No.4 magazine and note how the top edge left hand sidewall is higher than the top right hand edge. On this magazine, it is only the left hand edge that controls its depth of seating into the magazine well. Ever wondered why? It's because the right hand side top edge is deliberately lower in order to clear the magazine cut-off - if fitted. Obsolete from day one of production of course, but no one ever thought of amending the drawings to allow simpler/less complicated production. This feature does not apply to the 7.62mm magazine.

But back to the subject. As some have already noticed, even with a machined body, the variations in manufacture still means that the converted rifles fail to feed. Either by stubbing the nose of the round at the point of entry into the chamber or the bolt head failing to pick up the next round in the mag. You can wiggle the mag lips a bit but the answer really is to bring the magazine higher into the magazine well. As I mentioned, it's usually just a case of lowering the side walls of the magazine a tad just to allow the magazine to sit slightly deeper into the magazine well. I know from L42 experience that it just takes .010" or so to cure.

But there's more to it than that... The front top surface of the 7.62mm magazine also has a big part to play in this operation because it is also this edge that contacts what we call the 'magazine stop face' at the front inside of the mag well in the body, just below the feed ramp (remember these technical words as there's an exam at the end of the week...) There was a gauge for this and if my memory serves me right, it shouldn't be less that .035" in height because... I won't go on - but if it did, it was another one of those invisible "theres' nothing wrong with my ZF or DP rifle" faults that would condemn a rifle.

As you can see and maybe understand from that now that magazine fitting is not just a case of slap a new or used one in. And like the old .303" magazine, the 7.62 mag should be a nice tight snug fit. As I said in an earlier thread, and I quote "...if fitting or any adjustment of the magazine case is required"... then the magazine case will be numbered to the rifle. Numbering will be - blah blah blah and so on - in order that the case is not damaged. Anyway, there it is, a short pictorial essay on fitting and adjusting 7.62mm magazines. I can't comment on the Sterling magazines because I only ever had 10 or 12 or so kits, long after the factory had closed and didn't try them except to say that these DID work without any sort of modification to the bodies. But I suspect that once they'd encountered the many variations and tolerances, they have had to do a bit – just like Enfield found they needed to!

The photos that accompany this article will highlight the salient points so here goes:

The interior of the bog standard No.4 body, this time a damaged L8. The dates of the magazine well drawing show that the machining was very probably incorporated into the L42 production series.

The No.4 unmodified body showing the standard No.4 magazine front feed lips. They coincide with the undercut in the body giving them unobstructed clearance room.

This time a 7.62mm magazine showing the more rearward position of the feed lips against an unmodified body. Now, there is a real chance that the re- positioned front feed lips will obstruct the body. So to ensure absolute reliability, the body is machined as shown later.

Out of sequence but while the rear of the body was machined to clear the slightly longer rear feed lips of the 7.62mm magazine, it wasn't really necessary.

The two magazines, top-to-top, together. Now the different length of the rear feed lips and relative positions of the front feed lips are clearly apparent.

A newly machined L8 or No.4 body showing the deeper ledge in relation to the 7.62mm magazine front feed lips.

A perfectly fitted 7.62mm magazine in a modified No.4 body. Even in this case, it was unnecessary to chamfer the rear of the magazine well as it fitted and functioned perfectly - certainly with 10 drill rounds.

This picture shows the top sides of the magazine case that you might need to adjust in order for it to fit and feed properly. You could adjust the front top edge too but make sure that it sits up AGAINST the magazine stop face and doesn't slip in behind it.

The magazine well ledge that we've been talking about. I know it's obvious really, but it is this surface that the magazine sits up against.

Important this! The magazine stop face. The front top edge must sit up against this face and not slip behind it. A defective one will cause all sorts of problems. Not many people take much notice of this. It's an important feature on your rifle.