anyone try a 7brx

[hoene72]

Was talking to a gun smith today. Told him what kind of shooting I was doing he said something about trying a 7brx. Has anyone tried or ever seen one. Does anyone think that this might be worth trying or a waste of time and money.

Thanks

 

[twoodard]

I was just talking to a friend the other day about that. might be able to get near 7mm-08 light bullet speeds out of it. I would like to see one happen!!!

 

[357Mag]

7MUP

Hoene72 -

Howdy !

Can't spead directly-to a 7BRX wildcat, however; with permission.....

For a similar case capacity 7mm wildcat, .35 Remington brass can be run up-into a 7 X 64 Brennekke
case forming die ( Redding ).

The cases are sat on a "perch", made from a .308 shellholder, a flat-head machine screw of proper diameter to fit through the primer hole in the shell holder; and two jam nuts ( one above, one below shell holder ). In use, the extra screw length is positioned in the press' ram's primer arm slot
( example: Rockchucker press ).

The screws' head is reduced in diameter, so that the screw head can go partially up-into the case forming die; w/o making contact with the inside walls of the die.

For this 7mm wildcat, all that is required, is to perform a simple one-step neck down...
from a case of ( originally ) .35 cal down to 7mm final calibre; which is readily accomplished in one step.
The cases I've "bent-up" form as easily as squeezing butter in your hand. Formed cases fall from the forming die virtuallly on their own.

I have not noted the formation of a " doughnut " while forming prototype cases; using the process mentioned above. After all, there's no "shoulder shove" being performed.
Notwithstanding, a simple inside neck ream would assure any inside neck non-conformities are addressed

While .35 Rem has a nominal .466" rim diam, I have had no trouble shooting/extracting wildcatted
.35 Rem products from my Wichita WBR1375 action, which has a stock .308 bolt face; and an M-16
extractor. ( The wildcat in that exampl.... .35 Rem necked-down to .224 cal ).

For the new 7mm wildcat's chamber: a 7 X 64 reamer is run-in "short", to obtain a base diameter matching that of .35 Rem.

The 7 X 64 and .35 Rem already start with/have neck lengths that a very close to identical.
Once formed, neck length difference is within the range that most reloaders trim their cases to
( example: a couple thou' short of spec ). If any neck length shortage exists w/ the formed cases
( even if only a couple thou' ), case firing would result in cases "growing" to the final 1.920" oal spec

The closeness of both .35 Rem case taper to that of 7 X 64 Brennekke, results in .35 Rem basic cases being usable @ its stock base-to-shoulder length; and case oal. A fortuitous circumstance!

I call this wildcat " 7MUP ". Case capacity is a few grains < 7mm-08, meets or exceeds that
of a notional 7 BRX; and is arrived @ w/o having to perform shoulder " blow-outs ".
With appropriate reloading die selection, 7MUP can be loaded/re-loaded without need of the "perch".

I realise for many, the LR primer format would be abhorant.
But, I offer..... LR primers are not a " death sentence " on accuracy.

Wildcatting w/o need of custom dies or custom reamers ?!? It don't get much easier than that !
[ As an aside: P.O. Ackley himself, wildcatted .35 Rem down to 6mm ]

Now, if you'll excuse me.... it's time for my medication !

Regards,
357Mag

 

[Rustystud]

In my opinion the 6mm bullets max out the potential for the BR case blown out to BRX.

I would think the 6X 47 case wildcatted to 7mm would be a better choice.

Nat Lambeth

 

[gunsandgunsmithing]

There's not a very good selection of match grade lightweight bullets in 7mm yet, and IMO, the case is too small for the heavies that account for the bc advantage of the 7mm's. It might be a fun little cartridge to play with using midweight bullets
at 200-400 yards. I just don't see it beating the PPC/BR cases at short range due to bullet selection or the BR/BR Improved rounds at longer ranges for lack of capacity to push the heavies. JMHO. I agree with Nat and would look into a 7x47 lapua for a mid to long range caliber.