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I have a topper cast iron frame that has a round depression in the breech face where the case head rests against it. I'm thinking that could be a weak spot where the breech wall deformed from the stress of the cartridge pressure.

Either that or it was made that way and I never noticed it before!
One member had a 243 Handi with a possible crack in the standing breech near the firing pin, that's the only SB2 related frame defect I recollect, his barrel also shot loose.

Tim

 
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has anyone ever horribly over loaded one on purpose, to see what it can withstand?
hopefully when they were less expensive!

i bought the cheapest new single shot 12 ga sold, and added a 40 s&w chamber adapter.
on the first shot, i had on my motorcycle leather jacket, leather welding gloves, saftey glasses, and an impact resistant face shield. i had zero confidence in that gun! it worked well actually, other than a 8 lb trigger pull!
 

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Pressure isn't the only factor to consider, internal case head area and pressure determine breech thrust

30-30 .422" @ 42kpsi = 5874psi
357 Max .379" @ 40kpsi = 4513psi
44mag .457" @ 36kpsi =5905psi
do we know the breech thrust, and rated sammi pressure rating for 445 super mag?
 

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People certainly have. I have read posts of people claiming to have run what are essentially proof loads on sb 1 frames and since it worked once they were like "oh, h&rs can handle it!" I'm talking loads well in excess of what the brass can support.

But damage is often invisible, and cumulative. So if your frame is weakened, the next heavy or even normal load might be the one that breaks something that shouldn't be broken. Or the 100th. We never know what is happening where we can't see.

People who know more than me, for example tim, are comfortable running loads I am not. Not because I don't believe him, but because he's much more likely to be able to spot and address any problems that arise. I stick with things well inside the boundaries, because that likely limits the damage I can do when I think I know more than I do. :)
 

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has anyone ever horribly over loaded one on purpose, to see what it can withstand?
hopefully when they were less expensive!

i bought the cheapest new single shot 12 ga sold, and added a 40 s&w chamber adapter.
on the first shot, i had on my motorcycle leather jacket, leather welding gloves, saftey glasses, and an impact resistant face shield. i had zero confidence in that gun! it worked well actually, other than a 8 lb trigger pull!
There's actually no point in doing so, anyone can overload any firearm to destroy it, it's not going to give anyone any useful data without pressure testing equipment to define limits. MGM tested the TC Encore platform with the 300 PRC which is a 375 Ruger necked down to .30 cal, the large .540" case head and 65kpsi increased headspace on the frame to barrel which basically trashed the frame, so they loaded a round with 80gr of pistol powder and lined the barrel with 22Lr rounds and intentionally blew the entire gun up. H&R tested their guns to failure as well, the results was the offerings they produced were safe for those respective platforms, SB1 or SB2.

Tim

 
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do we know the breech thrust, and rated sammi pressure rating for 445 super mag?
As Ocho said, the 445 isn't a SAAMI chambering, there is no pressure standard, some of the old data was listed at near 50kcup, Hornady lists the velocity for 300gr bullets in the 445 (8" barrel) as 200fps faster than for the same in a 44 mag (7½" barrel), so you know the pressure is higher and why cast iron frames aren't a wise choice for the 445 which has the same case head size as the 44 mag.

Tim
 

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I would think the closest comparison to 445 (at top of the old data) would be slightly below 45-70 Ruger #1 loads. Hotter than buffalo bore +p 45-70 loads for marlins. Not sure how many of those rounds I want to shoot through an h&r, and definitely not with a buffalo classic lol, but 445 loaded within that data is very appropriate for a sb2.
 

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The link shows predicted conversions of piezo and crusher data for different rounds, but the 445 isn't listed, it does show the 44 mag tho, 40kcup was the "equal" to 36kpsi. FWIW the 45-70 has a much larger case head at .505"ish (depending on whose spec you read!) than the 445, the larger the case head, the lower the pressure needs to be for a platform given strength limit, Barnes data for modern rifles list a limit of 55kpsi for the 45-70 which I've shot in one of my 45-70 H&Rs which it handled the question is....how many times!

Tim

Cartridge Pressure Standards (kwk.us)
 

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There ya go with that frame stretch myth again, no such thing on an SB2, the underlug is the relief point for excess pressure,
I'm not going anywhere with any myth. I thought we were in a dialog about older (SB-1) frames handling high pressure barrels? So I was simply musing that the softer steel would stretch causing headspace issues. Please don't make an accusation against the veracity of what I am saying without clarifying my position. I don't know of any myths you are speaking of.
 

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I'm not going anywhere with any myth. I thought we were in a dialog about older (SB-1) frames handling high pressure barrels? So I was simply musing that the softer steel would stretch causing headspace issues. Please don't make an accusation against the veracity of what I am saying without clarifying my position. I don't know of any myths you are speaking of.
As the OP stated, the topic is high pressure barrels on early SB2 frames, not SB1 frames, and why H&R would only fit the original chambering to those frames as stated in the FAQs on the build code page. Can't speak to issues related to ductile frames other than ductile cast iron (SB1 or earlier) aren't suitable for any high pressure chamberings, only shotgun and low pressure chamberings.

There was a member that used a 270 or 243 barrel on an SB1 frame unintentionally resulting in a huge gap between the barrel and standing breech after being fired, then realized he'd put the barrel on the wrong frame, whether it stretched the frame or not he never said, but it certainly didn't do it any good.

There was another member that bought a 223 that was on an older frame with the swing lever release, an M48 or M1908 possibly, it blew the firing pin out of the frame, fortunately he fired it remotely so he wasn't hurt, that's in the FAQs as well.

Tim

 

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I would think the closest comparison to 445 (at top of the old data) would be slightly below 45-70 Ruger #1 loads. Hotter than buffalo bore +p 45-70 loads for marlins. Not sure how many of those rounds I want to shoot through an h&r, and definitely not with a buffalo classic lol, but 445 loaded within that data is very appropriate for a sb2.
i bought an sb2 to convert my 44 to 445.
was bummed my barrel did not fit quite right, but its close.
i will get it fitted sooner or later.
 

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I would think the closest comparison to 445 (at top of the old data) would be slightly below 45-70 Ruger #1 loads. Hotter than buffalo bore +p 45-70 loads for marlins. Not sure how many of those rounds I want to shoot through an h&r, and definitely not with a buffalo classic lol, but 445 loaded within that data is very appropriate for a sb2.
i only shoot common factory 240 grain 44 mag ammo on my sb1 frame.
and some hand loads, that are 18.5 grains of 2400 with 240 grain rnfp.
no hot loads on my sb1!
its a really clean gun, i dont wanna hurt it or me!
 

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I think I got confused and 445 sm is between 44 mag and 444 marlin in power, but it’s not something with a ton of data out there so I’m not 100% sure. If I wanted a “44” caliber rifle 444 marlin would be awfully tempting, with the ability to much easier get brass or even rarely factory ammo. Also there are 444 barrels available, and a few production rifles still made in that chambering (with ruger suggesting they might bring it back as well). Great loading data available.
 

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I think I got confused and 445 sm is between 44 mag and 444 marlin in power, but it’s not something with a ton of data out there so I’m not 100% sure. If I wanted a “44” caliber rifle 444 marlin would be awfully tempting, with the ability to much easier get brass or even rarely factory ammo. Also there are 444 barrels available, and a few production rifles still made in that chambering (with ruger suggesting they might bring it back as well). Great loading data available.
i like the 444 idea, or even 45-70.
being able to shoot 44 mag 90% of the time to save money, was the deciding factor.
plus i like having a rifle that can shoot the same ammo as my pistol.
this will pair well with my 1971 model 29-2.
 

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Makes sense from that viewpoint. I enjoy shooting 38 or 357 mag/max interchangeably. You could always buy a bfr for 444 or 45-70, but that seems a bit silly.
lol, 444 marlin in a handgun, ill pass!

i have a 1969 3 screw blackhawk 357, i love to shoot!
i now have a h&r tracker1 fitted with a 357 mag chamber adapter to pair with it.
357 is way fun, i will be shooting it tomorrow!
 
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