Anyone have the blueprints for 375HH vs 375 flanged?

[rookhawk]

Question I should know the answer to but do not. Is conversion of a 375HH belted magnum to a 375HH Flanged as simple as machining extractor spurs for a rim, or are there other differences between the cases?

 

[freefall]

I should think they'd have the measurements at loaddata.com.

 

[rookhawk]

I should think they'd have the measurements at loaddata.com.

The thing I'm not smart enough to figure out is "how" the brass works for headspace comparisons. The H&H has a belt for headspace, so there is literally no support for the body of the cartridge during ignition. Of course the flanged has the rim for headspacing.

Clarifying my question, does anyone have the blueprints for the chamber for both these cartridges so I can determine if a 375HH will "clean up" with a reamer to accomodate a 375HH flanged?

 

[BourbonTrail]

There’s some other differences (length and shoulder are slightly different.) I’m still looking for chamber dims

I did find some for sale.

375 Flanged Magnum Nitro Express - Rifle Brass - Metallic Reloading - Graf & Sons

www.grafs.com

Also found a reamer:

PTG Chamber Reamer: .375 Flanged NE (Nitro Express) 2.5"

.375 Flanged NE (Nitro Express) 2.5" Chamber Reamer at Pacific Tool and Gauge

pacifictoolandgauge.com

 

[Mark A Ouellette]

Page 131 of this SAAMI document has the cartridge and chamber specifications for the 375 H&H:

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://saami.org/wp-content/uploads/2019/02/ANSI-SAAMI-Z299.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

The above link is from Google Chrome. The parent page with the 2015 spec is here:
https://saami.org/technical-information/ansi-saami-standards/

The 375 Flanged is a CIP spec, which I can't find online for free...

I posted a photo of the two cartridges together months ago. It's in AH somewhere...

 

[rookhawk]

There’s some other differences (length and shoulder are slightly different.) I’m still looking for chamber dims

I did find some for sale.

375 Flanged Magnum Nitro Express - Rifle Brass - Metallic Reloading - Graf & Sons

www.grafs.com

Also found a reamer:

PTG Chamber Reamer: .375 Flanged NE (Nitro Express) 2.5"

.375 Flanged NE (Nitro Express) 2.5" Chamber Reamer at Pacific Tool and Gauge

pacifictoolandgauge.com

Thanks @BourbonTrail Trivia for you, that second link is for the 375" 2.5", a lethargic cartridge that gets confused for H&H belted and flanged magnums that are far more common.

 

[BourbonTrail]

Thanks @rookhawk for catching my oversight. For dims I grabbed the SAAMI doc, and a cartridge dim for the Flanged. Couldn’t find the chamber dims for it though.

375 flanged cartridge dims…

 

[perttime]

Wikipedia has case drawings with dimensions, and I see lots of differences.

.375 H&H Magnum - Wikipedia

en.wikipedia.org

.375 H&H Magnum - Wikipedia

en.wikipedia.org

 

[Mark A Ouellette]

Here's the photo:

 

[Frank375]

I think the 375 H&H Flanged is 2 tenths longer.

 

[Hunter4752001]

CIP specifications for 375 Flanged are at https://bobp.cip-bobp.org/en/tdcc_public?page=1&cartridge_type_id=2
Go to the cartridge and then download the appropriate pdf (in the TDCC column) .

 

[Mark A Ouellette]

Here is the 375 FL specs, thanks to @Hunter4752001

 

[steve white]

If you really, really want to go that route, then the best measure to take would be to cut the section out that involves the belt currently, and then SOLDER IN A RING OF STEEL TO FILL AND THEN RUN A PROPER CHAMBER REAMER. You will have to re-blue, but it will be solid and correct. Not much different than filling in a too deep shotgun chamber and starting over.

 

[Inline6]

I think the 375 H&H Flanged is 2 tenths longer.

Longer is not a problem, you can run a reamer say and 30-06 into a 308 no problem.

The issue is going to be the belt is wider than the case of the flange.

If you really, really want to go that route, then the best measure to take would be to cut the section out that involves the belt currently, and then SOLDER IN A RING OF STEEL TO FILL AND THEN RUN A PROPER CHAMBER REAMER. You will have to re-blue, but it will be solid and correct. Not much different than filling in a too deep shotgun chamber and starting over.

I know nothing of shotgun work, that said....shotguns run a much lower pressure than a rifle 14k vs 47k of the flange. I'm not saying it could not work, I would not bet my life with it.

 

[JimP]

Just a FYI, you don't need to headspace a cartridge off of the belt or the rim. You will get more reloads out of a case that is just headspaced on the shoulder, even with the tapered shoulder of the 375 HH.

I shoot a few wildcats based on the 30-30 case with a rim, all my reloads are headspaced off of the shoulder after fire forming them

 

[steve white]

Longer is not a problem, you can run a reamer say and 30-06 into a 308 no problem.

The issue is going to be the belt is wider than the case of the flange.



I know nothing of shotgun work, that said....shotguns run a much lower pressure than a rifle 14k vs 47k of the flange. I'm not saying it could not work, I would not bet my life with it.

When I said "cut the section out" I only meant a tiny portion--INSIDE the end of the chamber, to be filled level with a soldered in ring. I bow to others experience whether higher pressure could undo something trapped inside the end of the chamber.
The procedure is covered in the late Ralph Walker's book "Shotgun Gunsmithing"

 

[Inline6]

When I said "cut the section out" I only meant a tiny portion--INSIDE the end of the chamber, to be filled level with a soldered in ring. I bow to others experience whether higher pressure could undo something trapped inside the end of the chamber.
The procedure is covered in the late Ralph Walker's book "Shotgun Gunsmithing"

Know what you were getting at, I'm not an expert. The ring is so small I'm not sure it would hold up. Then what would happen? I'm not sure how that could play out.

 

[freefall]

Obviously we need a weekly "Ask JJ Pedereau" column.

 

[frog stealer]

You’ll have to set back the barrel to get rid of the belt section…no one will do this work, I’ve tried. They will rebarrel.