Drilled and tapped through chamber.

[otblue]

I inherited a WW2 vintage SMLE which had a home machinists weaver type bridge mount installed. I have fired hundreds of factory rounds through it without incident except that the base interferes with case ejection. The ammunition was from a variety of manufacturers, FN, old Dominion and Super. I have reloaded these cases many times even the berdan primed ones, without further problems and no separations that 303 SMLEs are notorious for. Recently started using newly manufactured Winchester brass and the separations started despite the care I take with resizing. Most of my reloads are at the starting load level with some at maximum recommended loads. I also noticed a small dimple half way up the case, something I never saw on my other brass. I was planning on removing the scope base anyway and when I did sure enough one of the holes on top of the barrel had been drilled right through into the chamber. FN factory loads are loaded to maximum pressures for SMLEs at around 40000+ cup and I didn't notice anything. So at what pressure does cartridge brass puncture like in the photos of pressure testing equipment published in some manuals. I only saw this brass dimple in the Winchester brass and I think only because the mount screw didn't extend all the way to the chamber being short about 2mm. What pressure can a high tensile screw (loctited or epoxied) into the barrel withstand. What I am really asking is whether I can or should continue using this rifle provided I fill in the hole with a properly fitted screw. Thanks for advice.

 

[krs]

You know that your easy answer is to toss that Winchester brass, right?

As to filling up your 'dent' with a longer screw....probably be OK if you're able to get the screw very well fitted. If I were gonna' try that I think I'd get the inside end of the screw as flush as I could outside the hole then install the screw and then run a chamber reamer in that caliber in to complete the job on the screw. It'd be a tedious job.

I don't know .303's but unless it's a straightwall cartridge behind the neck I don't think I'd want to chance using a straight reamer or any other cutter that didn't match the shape of the cartridge for fear of changing the chamber dimension even a little.

Can you compare the case wall thickness between the Win. brass and whatever surplus cases you've used without problems? Sounds like it must be thinner, maybe a lot thinner.

 

[Jim Watson]

Pressure guns will blow the case wall at the piston or transducer at something well below 20,000 psi. Yours didn't only because the diameter is smaller and the pocket formed is shallow.

I consider the barrel ruined, but since it hasn't blown the scope base off yet, we can think about how to get away with shooting it some more. If you don't want to go to the expense of a chamber reamer, you could produce a better plug just by taking a good screw and filing it until the end was flush with the chamber wall, with many repetitions of screw it in, look at it, screw it out, file a few licks, screw it back in. Get it flush and then Loctite it in place.

 

[rcmodel]

I think you could file the end off a screw to match the radius of a fired case.

Then screw it in with red lock-tight on it, against a fired case in the chamber, 1/2 turn at a time until it was flush.

Then after the lock-tight cured overnight, saw off the end left sticking out of the receiver and file it down smooth.

Any roughness left inside the chamber could be polished down flush with 400 - 600 emory paper on a dowel rod.

Still, the barrel is ruined, with no margin of safety left, and I'm not at all sure it is safe to continue shooting it.

If it was mine, I wouldn't.

rc

 

[Jim K]

The chamber pressure may be 45k pounds per square inch, but that hole is only a small fraction of a square inch, so the pressure in that spot is really negligible. I have no doubt at all that the screw will hold for just about ever.

Jim

 

[otblue]

Just back from the gunsmith. Said he sees this all the time with old SMLEs. Put a small setscrew in the hole until it touched a chambered (fired) case then backed it out half a turn. Then put another screw in on top of it. All loctited of course. Said the interference fit gave it additional strength. Said it would hold with any factory and any sensible reload. Left to me to tidy up the outside after it all sets. Will section and measure cases tonight.

 

[therealdoublel]

maybe coat the screw threads in J-B Weld, let it cure overnight and it should do a fair job of sealing it, not sure how it would stand up to the heat though.

 

[otblue]

OK, sectioned some cases for comparison and found the cause of the obvious difference in longevity. IVI headstamped that have been reloaded multiple times over the last 15 years have a wall thickness of 0.8mm at the approximate same level as the separations on Win brass. Winchester brass (which I have not had problems with in other calibres) is only 0.65mm thick. This might not sound like much but the difference is glaringly obvious to the naked eye. Despite this they weigh in almost the same at 175gn because of differences in the construction of the solid head. I will keep using the rifle given that I have fired it with hundreds of "proving" loads and the gunsmith has checked and sort of repaired it. I will stick to mild reloads using proven brands of brass.

 

[krs]

It was that you said that you'd been firing it right along that brought me to make suggestions as to how to fill the 'dent'.

Great! New life for the old girl, eh?