No4 Scope mount holes misaligned and drilled too deep?

[Chris7171]

And whoever thought that small BA (or close to....) threads going into 3mm or so of mild steel revceiver ring would be sufficient to hold firm was living on another orbitory planet to the rest of the world.

Well I think that this statement is absurd!

Let’s think of a Parker Hale L82 (C3) sniper rifle, their mount has 4 very small bolts that are attached to the receiver which is 3mm thick!!
So peter are you saying that these rifles are badly engineered (I don’t think so) they give suburb service to Australia, New Zealand and Canada.

I do agree about the Pecar scope the ZF69 was the pick of the lot.

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[Peter Laidler]

'So peter are you saying that these rifles are badly engineered........' . No. The rifles were perfect. In fact the P-H constantly beat the AI L96 for accuracy. Am I saying that the telescope mounting was badly engineered. Speaking as an engineer and someone who's been in the Military small arms system for a tad over a year or so, then I'd say that the tele mounting system used on the Enforcer wasn't just badly engineered, I'd say that it went beyond that. I don't know enough about the mechanics (receiver ring thickness etc) of the PH fitting to comment. But I DO know a few things about the Enfield

[Chris7171]

Here in NZ there were hundreds of Enfield’s that were used for deer recovery fitted with the PH top mount and a scope that is attached in the manner discussed here, these rifles were very poorly handled & treated I would go so far as to say way worse than in the military as another rifle cost very little if the rifle was lost or dropped out of a chopper etc, none of these rifles suffered any problems with their PH mounts or how they were attached and indeed there are still loads of these rifles still in NZ giving good service to this day after years of abuse with this mount this must count for some thing?

[Peter Laidler]

The UK MoD could have adopted a 'new- build' L39 enforcer type sniper instead of the L42 but the trials dictated that it wasn't robust enough. Likewise, during the 80's we could have adopted the more accurate (than the L96) PH sniper rifle. virtually off-the-shelf on the basis of the Can; NZ and Aust. experience but once again, it wasn't robust enough for what a sniper rifle needed to be. It had to be a readily take-off mount for the telescope among other things.

I feel the urge to repeat the process of trials that took place between the contenders but I don't think it will be possible/allowable. But suffice it to say, those mounts didn't get past the first hurdle for a sniper rifle. It's ironic that in the midst of this, the 3 nations have now adopted the L96 or variations of it. And I know for certain the Australia did solely on the basis and say so of our Warminster trials

As I always say..........., You cannot even compare sniping with other forms of shooting. There's a world of difference between the different and various sporting rifles. But sniping is the only sport where the quarry shoots back.

I know it's being a bit pedantic Chris, but are you sure that NONE of these hunters rifles suffered any problems? Surely one or two might have...!

[Patrick Chadwick]

and third and more worrying, the holes seem to have been drilled right through the receiver and into the top of the barrel threads

Quite right to be worried. In Mauserland the rifle would be viewed as unsafe by a proof house. My local dealer showed me a Mauser where Bubba had done just that. The proof house refused to accept it for proof firing. Then he had welded up the holes, and presented it again. Bubba now has an officially condemned wall-hanger.

[Thunderbox]

Quite right to be worried. In Mauserland the rifle would be viewed as unsafe by a proof house. My local dealer showed me a Mauser where Bubba had done just that. The proof house refused to accept it for proof firing. Then he had welded up the holes, and presented it again. Bubba now has an officially condemned wall-hanger.

Its quite common to find PH BA20 mounts where someone has replaced the short screws with much longer ones, and the holes have been drilled down through the breech ring into the barrel itself. I've never heard of one of these rifles failing UK proof, as the proof houses are not into the business of dismantling rifles to check scope mounts, etc. Only if there is a noticeable incident with the proof cartridge will the rifle be examined. The holes have to be practically through the chamber wall before anything much happens. I have heard of one or two rifles where the mount holes were so deep that fired cases ended up dimpled as the chamber wall had subsided a fraction over the holes.

[Peter Laidler]

I'm sitting firmly on the fence here as my limited knowledge is really limited to the military aspects of firearms. BUT........., ahem......, on the basis that 'people' do indeed drill into the barrel (ouch!) to mount these pads more securely then surely it'd be better if they just drilled in to a much shallower depth and used a more substantial, say a 0 or 2 BA ish dia screw. I'm thinking tooth root strength and all that engineering stuff.

But I think we're all agreed that drilling into a barrel is what I'd call in technical language 'p--s poor engineering practice'

[jmoore]

When the holes go into the chamber, it seems that the cases will blank out discs into the hole until the last one won't quite clear, and the case doesn't want to extract. (Saw this once.) The other thing that I've seen is that the poorly threaded hole won't retain the screw, and it pops up until it won't go further. (Saw the remains of a couple of those, after the fact, in a junk pile.)

USUALLY, nothing happens because the driller has a clue or a conscience (generally not both!) and the barrel is scrapped.

There is the rare instance where the perpetrator has caught his mistake, run a set screw into the hole, dressed off the bottom flush in the chamber, and continued on mounting the scope. Haven't seen it myself, but it was related to me by one of the 'smiths that "trained" me many moons ago.