More on Alternative Brass

[pitted bore]

The recent thread in this forum titled "Alternate cases for forming 450 Bushmaster" (LINK) has been confined to a discussion of the 7.5x55 Swiss as a possibility. Rather than hijack that thread by describing other candidates for conversion, I'll start another.

To be a reasonable conversion candidate, a cartridge should show some obvious characteristics.

• It should have a case head diameter of about 0.50 inches, with perhaps a few thousandths over, but very few under. A sizing die can decrease the diameter to the brass, or the brass head can be turned a bit at the head region.
• The case should be sufficiently long to achieve easily a final length of 1.700 inches.
• Cases should be relatively inexpensive, and readily available.

I reviewed some lists of cartridges and dimensions, and came up with three cartridge cases that seem workable by the above criteria.

[1] 45-70. In this straight-walled case, the head is nominally .504" max, length is 2.105". It's available currently; Midway has it on sale at 70 cents each. Conversion to 450B would require turning the case head to remove the rim and to form the 450B rebated rim and extractor groove. Cutting to length is not a big chore. My sample 45-70 case has pretty thin walls, so the converted cartridge may not require reaming to produce usable neck wall thickness. If the case is a little larger in diameter than the 450B case, the 450B FL resizing die will reduce it easily. If the case is larger than 0.500 just in front of the new extractor groove, the resizing die may not reduce it at that point; a light lathe cut will bring it into spec.

The web of my 45-70 sample case is about 0.17" thick. The web of sample 450B Hornady cases is about 0.20" thick, so converted 45-70 cases may not be as strong as the 450B case. Cuts for the extractor groove should lie within the length of the web. However, it would be wise to section lengthwise a converted 45-70 case and compare it to a sectioned 450B case to see any obvious case head weaknesses.

[2] 45-90. These cases are dimensionally like the 45-70 except they are a bit longer. The same procedures as with the 45-70 should convert them to 450B dimensions. They are available, and cost about $1 each.

[3] 376 Steyr
This cartridge has a case head of 0.506", and a case head to shoulder length of 1.89. It's available currently at about $1 per case. The neck and shoulder would have to be amputated, and the rim and extractor groove turned to proper dimensions, like the 7.5x55. Like the two 45s above, the FL 450B sizer will bring most of the case length to proper dimensions. If the portion of the head that can't be formed by the sizer die is too great in diameter, a gentle touch with the lathe can bring it down to 0.5000. Fire forming may be needed, and perhaps reaming of the neck if the case walls are too thick.

If there are other candidates for reforming that meet the criteria of head size, case length, and availability, then posting these others will be helpful.

--Bob

[BillytheKid]

Please pardon my complete lack of experience here...what about S&W .460 brass?

Bill

[Hoot]

Please pardon my complete lack of experience here...what about S&W .460 brass?

Bill

It's rimmed brass like 45 LC Bill. I've heard tell of folks working on an AR action that will reliably cycle rimmed brass from a single stack magazine, but I haven't seen a working model yet. The 800 pound gorilla in that process is obviously getting the case to not hang up on the one beneath it or the magazine. Then there's the challenge of the extractor hook groove cut into a barrel extension that will register with a rotating bolt. It would be an Engineering Marvel to pull it off reliably.
At least the 460 S&W has a modern form factor extraction groove above the rim (unlike the .45 LC). That's a bigger plus than you might imagine. The challenge would be getting the extractor hook to engage the rim and groove before the bolt and bullet enter the barrel extension. Perhaps the solution lies in some variation of Controlled Round Feeding. I wouldn't be surprised to see something some time this year once (if) the demand for existing caliber rifles starts to moderate.

Hoot

[pitted bore]

Please pardon my complete lack of experience here...what about S&W .460 brass? ...

Bill-
Are you asking whether 460 S&W brass can be modified to the approximate dimensions as 450B brass? If that's your question, then the problem is the difference in the size of the brass cylinder.

In front of the rim, 460 S&W brass has a case diameter of 0.478 inches, and it holds that dimension from rim to mouth. The 450B has a diameter of 0.5000 in front of the extractor groove tapering to 0.480 inches at the mouth. That means that the 460 is 0.022 inches too small in diameter at the rear of the case.

Just as with the 45-70 brass, it would be relatively easy to turn the rim area of the 460 case to 450B dimensions, and to shorten the 460 case to a length of 1.700 inches. The open question is whether the head area of the converted case, in front of the new extractor groove, could upon firing withstand the expansion of 0.022 inches without rupturing. I suspect that 460 brass is pretty tough, since it designed to handle the exceptionally high 460 S&W pressure.

I'm currently working with an old rolling block rifle chambered in 8x58 Rimmed Danish. That brass is scarce, but the 8x56R Austro-Hungarian Mannlicher cartridge can be fire formed to fit with little problem. The 8x56R brass toward the head of the case is 0.008 inches too small in diameter. The solid web of the case directly in front of the rim is solid and won't expand, but in front of the web the bulge is really noticeable.

With three times that amount expected in the 460 to 450B conversion, the bulge would be at least really obvious, if it didn't cause a split. Also the expansion would cause the converted case to shorten significantly, which might cause problems in headspacing, since the 450B headspaces on the case mouth.

I'm not sure if this answers your question. If not, try again.
--Bob

[wildcatter]

Bobber,

With some fiddle the 45-70 could/can be made to work. As for your assertion about the 45-70 not being as strong as the 450b, is correct and it would be possible, I've done it, to over exert that brass to failure (However, John Linebaugh doesn't seem to have these problems and he loads his revolvers to pretty hot standards). But, if loads were kept low to moderate, making sure the action fully & reliably functioned, the 45-70 is an excellent candidate for someone with a mini-lathe. Meaning, we have been opening a great can of worms here. I will keep the ball rolling.

Open the attachment..

..t

Convertible cartridge candidates.docx

(17.33 KiB) Downloaded 743 times

[pitted bore]

T-
That's a handy listing.

With the 45-70 cartridge, there isn't much web remaining in front of the extractor groove cut after conversion to 450B, which is the reason for suggesting that a modified case be sectioned to see whether there might be cause for concern. Linebaugh can probably push the pressures in his 45-70 cases upwards, because the head of the case isn't altered and the web remains strong and intact. The metal removal with conversion to 450B is a possible concern, and will need to be checked. It's also possible that some brands of 45-70 cases have thicker webs than other brands. If so, these brands of cases should be selected for conversion.

In selecting the three cartridges on my short list, I considered most of the cartridges on your list, or at least the parent cases, and discarded those that are not currently available or that are relatively costly. Probably the 8x56R Austro-Hungarian brass should have been on my list. The PPU brass in that caliber is a possibility since it's relatively inexpensive. I've got some in my stash.

Fortunately, I think I have sufficient 450B brass to get me through the experimental work I have planned for next summer, so I don't have to think really hard about actually making some conversions. I may try to finish the sample Swiss case I started, just to see if it can really work.

Thanks.
--Bob
edited for clarity

[tbirdman74]

www.3rdgss.com

They have some 450 brass in stock if anyone's looking.

[Jim in Houston]

My alternative brass is once fired by someone who does not reload. Pick up those empty cases and PM me. I will pay $.25 per case (or make me an offer) plus USPS bulk rate shipping.

[Texas Sheepdawg]

.......

[pitted bore]

In his post above on 28 January 2013, wildcatter included a MS Word attachment listing some candidate cases for conversion to 450B. The list may be of interest should 450B brass become unavailable.

Because my computer is really slow in converting Word docs, I converted wildcatter's document to plain text and set it up in a code box to maintain column integrity. I've edited the names of the cartridges so they fit within a reasonable length limit.

Here's the list:

Code: Select all

Using ammoguide.com, searched for rounds where:
    Body width is equal to .5 ± .006
      ...and...
    Case length is greater than 1.7

Search Results: 33 cartridges matched


  Cartridge      Bullet  Shoulder Body     Rim    Case    Case
    Name          Dia     Width   Width   Width  Length  Capacity
       
.224x284 ALS      .224    .485    .500    .473    2.045   59.9        
6mm-284 Win       .243    .475    .500    .473    2.170   65.3        
.25-284           .257    .475    .500    .473    2.170   65.6        
6.5mm-284 Norma   .264    .475    .500    .473    2.170   65.5        
.270-284          .277    .475    .500    .473    2.220   67.0        
.284 Winchester   .284    .4748   .500    .473    2.170   66.4        
7mm YRM           .284    .485    .505    .610    2.695   84.1        
.30-284           .308    .476    .500    .473    2.170   67.2        
7.5mm Swiss       .308    .457    .498    .498    2.189   64.3        
8mm Danish Krag   .322    .460    .500    .575    2.280   64.9        
8x50mmR Aust      .323    .476    .496    .559    1.976   60.4        
8x56mmR Hung      .329    .478    .494    .559    2.195   65.5        
8x52mmR Siam      .330    .463    .504    .561    2.045   61.8        
.338 TPC          .338    .495    .500    .473    2.170   70.5        
.338-284 CanKCG   .338    .475    .500    .473    2.170   67.9        
.35 Greevy Expr   .358    .480    .502    .600    2.100   67.2        
.358-284          .358    .475    .500    .473    2.170   68.8        
.375-284          .375    .474    .500    .473    2.170   68.9        
.376 Steyr Imp    .375    .494    .506    .496    2.362   79.0        
.376 Steyr Sh     .375    .491    .501    .494    2.020   65.2        
.376 Steyr        .375    .4748   .506    .496    2.362   75.9        
.38-70 WCF        .378    .421    .506    .608    2.340   66.9        
.40-82 WCF        .406    .450    .503    .604    2.400   73.4        
.40-65 Win        .408    .432    .504    .608    2.105   65.4        
.416 Barnes       .416    .484    .505    .595    2.112   68.6        
10.75x68mm        .424    .480    .495    .495    2.677   87.7        
.450 Bushmaster   .452    .476    .500    .473    1.703   57.5        
.452 JBX          .452    .472    .504    .608    2.105   71.1        
.45-110 Sharps St .458    .489    .505    .608    2.870  100.6        
.45-120 Nitro Exp .458    .490    .505    .608    3.250  114.1        
.45-120/125Sharps .458    .490    .506    .608    3.250  114.4        
.45-70 Govt       .458    .4800   .5055   .608    2.105   72.5        
.458 Tatanka      .458    .480    .505    .608    2.275   78.3


It's odd that ammoguide shows the length of the 450 Bushmaster cartridge as 1.703". The maximum SAAMI cartridge length is 1.700". There is no "plus" tolerance on this dimension. The "minus" tolerance is 0.010"; that is, a minimum cartridge length of 1.690".

If errors are found in the table in this post, please let me know via PM and I'll repair it.
Thanks.
--Bob