.284 Winchester PROOF cartridge

This was the second round that I bought from Merv at the Easter gun show in Calgary.
My first proof round and it’s a great one.

Why did they make the .284 with out an extraction groove ?
I have a few ideas but am really curious as to the reason for this.


Good luck Stonewall. I’ve asked this question more than once and have yet to get an answer. The most recent was earlier this year. Do a search.


I will go out on a limb just to establish a base for further investigation of these rounds by those that collect them. These proofs without any rim are much, much rarer than those that are loaded in standard case, although usually tinned or nickeled, with extractor groove and rim. Could these be for pressure test fixtures, to establish the SAAMI-recommended pressures for a barrel proof load, rather than actually proofing firearms themselves?

Perhaps one with more interest in sporting rifle than I have should contact SAAMI and ask them the question. When I have needed information, SAAMI has generally been helpful. Remember, they are the ones who regulate this kind of thing in the firearms industry, and they may be the best source to explain this form of proof load.

John Moss

Good suggestion.

I don’t collect proof cartridges except for a handful of different ones for reference and show-and-tell. I don’t think I’ve ever seen a 284 Winchester proof with the standard groove and rim. That doesn’t mean a whole lot coming from me but maybe someone reading this has seen one??


Ray - that’s interesting information. I wonder if it is something unique to the 284 Winchester that they don’t have a normal case head? I have had all kinds of American proof loads go through my hands over the last 40 years or so, commercial and military, in a myriad of calibers and I have never had any that did NOT have a normal head. However, I have not, to my memory, every had or seen a proof load for the .284. I guess the mystery deepens. Good information - thanks.

John Moss

Ray–I agree with you. I have never seen proof loads for the .284 Win. (They come in both Super-x and Super Speed) that had normal heads. Likewise, I know of no other modern (Post 1950) proof loads other than the .284 Win. that are rimless and/or grooveless. I wonder if it has something to do with the rebated rim of the .284 Win.

Don’t be shocked…but I have a decent collection of proofs (“special purpose”)…but I am not a student of them. Do you think someone from SAAMI would have that answer?. Ken Green is their Technical Director and is an IAA member (and a buddy)…can ask if you think he would know the answer. (Wouldn’t a Winchester rep know better ?)

here’s a reference file photo of the proof drawer


Pepper - It is SAAMI that sets the pressure levels for proof loads. They might know. If you have a in with someone who is really a technical expert at the Winchester factory, of course, that would be the best. My experience with Winchester reps is that they are highly competent and familiar with the ammunition line, but not very familiar with items that are not sold either to the public, or if they are LE reps, not sold to LE. Proof loads, generally speaking and by policy, are usually only sold to people or firms holding an FFL Manufacturer’s license. Of course, there have been exceptions for obsolete loads, etc. Normal Reps therefore don’t really have much to do with them.

John Moss

Note was sent to SAMMI !

Super interesting mystery! Just curious, what is SAMMI?


“Note was sent to SAMMI !”

Thanks Pepper -that’s what I had in mind when I posted those photo’s but didn’t have a contact -person to send them to.

What’s the cartridge with the[color=#0000FF] blue band [/color]?

Any European hunting cartridge PROOF rounds out there ?



here it is with it’s rebated rim and the aforementioned rimless

PS…the blue band ? wise guy answer is “a proof”

the honest answer is I need to check if I have a note on it…I answer 90% of these away from my collection…so another trip to the “bullet room”

stay tuned

Nice drawer, Pepper!

The two varieties of .284 Win. proofs shown got me thinking. One possible purpose for the rimless/grooveless type rounds might be for the process of autofrettage where high pressure rounds are used to work the rifle chamber to produce improved steel structure. Gun is not finished, no extractor, etc. If I understand the concept right, I would think some plastic deformation of the chamber dimensions would be part of the process and the cartridges used for this might be undersized. For all I know the process hasn’t been used for modern commercial rifles, but…

Curious if perhaps the critical diameters would be different between those two rounds. Or am I off base on the autofrettage thing?


My bet is that Winchester had problems with the case gas leaking through the extractor groove in this caliber POOF rounds because of the rebated rim case design.
Or the primer pockets expanding because of PROOF pressure and a gas leak which would damage the bolt face of the tested rifle.


The blue banded round ?

It is a 416 and no special notes with it (any ideas ?)

it (and the non blue banded example next to it) are both H/S
(416 PROOF B PROOF)…yes “proof” twice


Pepper–I picked up one of those .416 Rigby Proofs (Without the blue band) at SLICS. It was made by B.E.L.L. It is the only Proof round that I have seen that has “PROOF” as part of the headstamp.

makes sense…I will write Jim and ask him why the blue band



Ron - there are at least two other headstamps with the word “PROOF” spelled out on the headstamp. One is a .303 British found in the original loading as well as on a crimped blank. They were made in Canada and have CWB cases, and the headstamp “DAC 1944 PROOF” with the “C” in the “DAC” having the broad arrow within the letter.

There is also a .380 Auto, and some other pistol calibers that I do not recall and just cannot search out in my notes right now, with the headstamp " + 380 PROOF" Oddly, the actual mark where I show a plus sign is the NATO mark. The " + " is enclosed in a circle. These were reportedly made in Spain, and have not other identification to show they are a proof load and no date or factory designator.

I think the Spanish one also occurs on .38 Special, and perhaps one other caliber. Just not up to going downstairs and researching it. Perhaps someone else knows. I think they are fairly scarce. As far as I recall, I have it only in .380.

John Moss

John, The 380 proof load you have with “PROOF” headstamp was actually made by Aguila of Mexico for the gunmakers in Eiber Spain. It also exists in 38 Special (Otto W has one) and in 9x19mm. I got the three of them as a set from a Spanish collector 3 or 4 years ago. The 9x19mm came in a commerical Aguila box with an overlabel identifying it as proof. What doesn’t make sense is why they put the NATO mark on non-NATO cartridges like the 380 and 38 Special.



Thanks. How stupid of me not to remember that. The .380 even has the typical Aguila/Remington Pointed bullet. I recall now all of what you just reported, and it is completely correct, of course.

Thanks for keeping me straight. All that is probably in my files, but I didn’t feel up to digging it out.