Replacement booster cones

[bbrown]

I'll take four (4) 10mm MG42 booster cones.

Bryan

[Smoke01]

I would be in for at least 2 MG42 10MM cones

Thanks

Smoke

[42rocker]

Ok, that sounds like 21. Bump back up for this one. Good Luck with selling a few more.

Later 42rocker

[noonxnoon]

Wait...don't count me out...

I need to get the sizes though...please don't say I gotta ream 'em myself!!

I'd basically want to get the 4 main 42 nozzel sizes...anyone have that knowledge immediatly on hand??

[CRUSADER]

The board member who might be manufacturing the boosters - TactAdv - plans to offer one size that can be drilled out to the desired size. His plans are for a 10mm orifice.

So charge up the batteries on your Makita and make sure you've got some good drill bits

[noonxnoon]

I didn't wanna ream 'em myself!

Ok...for the flip side...were there any 42 cones with holes less then 10mm?

[DARIVS ARCHITECTVS]

Gentlemen,

The original booster cones appear to be hardened. Although this is not necessary for function, it does allow you to use a hardened scraper to remove the carbon deposits for routine cleaning without marking the booster cone. The rear end of the booster cone will experience wear due to impact, such that a hardened cone is very desirable if you want it to last a lifetime. Case hardening is certainly an option.

[TactAdv]

Gentlemen,

The original booster cones appear to be hardened. Although this is not necessary for function, it does allow you to use a hardened scraper to remove the carbon deposits for routine cleaning without marking the booster cone. The rear end of the booster cone will experience wear due to impact, such that a hardened cone is very desirable if you want it to last a lifetime. Case hardening is certainly an option.

Hi Kurt! Awhile back, we did both a Rockwell-DC test and a Brinell test of two existing booster cones, one a wartime MG42, and then a well used M53 one. They both came in the very common 26-32Rc range on the Rockwell test, and with a bit of difference on the Brinell, both about ~290 BHN, which tracks as expected for common steel alloy material that has been work hardened.

From a metallurgical standpoint, I'd put them all as common high-carbon steel alloy, showing the expected work hardening from manufacture, only. Likely a common-range mixed austentitic-pearlitic machining steel. I saw no evidence- grain features, crystallography, etc., that would indicate any attempt at further annealing or later normalizing after even a simple carburization salt bath case-hardening. And I see no possible reason to even consider this part for actual through hardening ever, as its service usage would undergo severe problems for a through hardened part that is constantly exposed to high-frequency virbrations and thermal cyclic strain. A through-hardended part would simply crack, and quickly. What is desired is a part with, nominally, a -reasonably- tough exterior feature over a resilient core.....something a common work-hardened surface treatment would provide.

Having no access to the actual production specifications I can't say for 100% certain, but a reasonable forensic analysis of the existing parts does produce those observations from a materials standpoint.

I plan on using a high quality common high-carbon steel, normal work hardening- will probably use 4140PH (normally about 58kpsi yield strength). This will produce finished parts with a surface feature of Rc 26-32 range nominal. Going harder, doing a true case-hardening to something like Rc 48-53 would be possible, using even a 4140QT if we don't want to do the full outside-vendor heat treat, but I can almost guarantee that it WILL CRACK.

Rc 26-32 will withstand just about any common "carbon scraper" usage if you don't go Neanderthal with the tool. ;-)

And as I first said, I am just peachy using 316L stainless as I have before. It is not as hard as the above 4140PH, coming in near Rc20-22, but it is superior in the caustic environment if you don't clean your guns. I have used it before with little problems, and would be happy to make a few, at the actual cost differential, if anyone wants. I'd only recommend these for people with some understanding of the material though.

-TomH

[DARIVS ARCHITECTVS]

I concur, Tom. Really nice to have a fellow engineer/metallurgist in our group! You are correct in that going to RC 48-54 will cause cracking. Such steel is best used in small knives. I think going with a 316L stainless is unnecessary, particularly if you drive the hardness down to RC 22. the small "feet" on the rear edge of the booster cone on my MG-42 exhibited some peening damage, with a slight burring over the life of the gun. Also, corrosion is not a major problem for this part. What is a problem is sticking of the part due to excess carbon deposits if the gun is not properly cleaned, hence the soldiers were issues carbon scrapers of high carbon steel to scrape the deposits off. I can tell your from experience that those deposits of solidified molten carbon are tough to remove in the extreme, and even soaking in kerosene (per military practice) was only partially effective in softening them. I used a fine deburring wheel (LIGHTLY!) to remove the remnants on external surfaces and a steel scraper on the inside.

[Gulfstream4]

I did not want this to just fade away. Is this going to happen? Any progress?

[TactAdv]

I did not want this to just fade away. Is this going to happen? Any progress?

Patience, grasshopper. ;-)

I indicated that I wanted this to let run a couple weeks to see who all was interested........it's only been a few days.

I am busier than a long-tailed cat in a room full of rocking chairs right now anyway......best guess is sometime in the next 4-5 weeks???

There is enough interest so far for sure to do both MG-42 & MG-15 cones......

-TomH

[mksshoot]

I would take 4 MG42 cones as well. Give a holler when your up and going.

[jcmg42]

Could you clarify the sizing of boosters?

http://www.robertrtg.com/mg42boosterset.html

[man_am_boden]

Did this happen? Or is it still possible to happen?

[TactAdv]

No, this has not happened....yet. Due to recent workloads picking up dramtically, it had to take a back seat to other work.

I still am planning on doing it, I feel there is enough interest here to warrant a short run of each type, it's just going to be hard to get it fit into the planning for awhile. ;-(

-TomH

[CRUSADER]

I'm still in, fwiw.

[crash520]

Gents,
For thoses who only ever wnat to buy one, once you have sorted your hole size, what about hard chrome plating?? i'm no metal guy or chromer but just a thought?

BR
C

[1fozziebear]

Late to the party, but I'd take two

[Der Alder]

Any word on these yet?

[Blanksguy]

TomH,
I too would be interested in 3-5 (or more) of the MG42 Booster-Cup at 10mm (depending on pricing).

I believe that you are corect on the type of steel used.......work-hardening plays into this along with repeated high temps. during firing and cool-down over the years.

Let us know when this happens and pricing when available.

Last question, what are the advantages of Stainless-Steel over the com,mon high-carbon steel that you also chose to make this short run in (?).
With this information, we could possibly give you a better idea of how many of each type steel requested for this "run" before you start cutting steel......(?).

Regards, RichardS in MI.
US Army, Retired.
Blanksguy2001@chartermi.net