New Concoction in 7mm?? What the HECK!

[ALO]

Now, I've been thinkin"! ??? (Uh-oh) I was wondering if someone has ever considered a 7mm BR. That would seem like logical progression, having as 22BR, 6BR, and a 30BR. Hart barrels offer a 1-14 twist in a 7mm barrel and I think if you could use the Speer 110 grainer 7mm bullets of 120 grainers or maybe even a slightly lighter bullet. Would one get the accuracy of a 30 BR? Or of a 6mmBR? I know that would be tough to beat - especially with Randy Robinett's bullet. After all it is off the same parent case!

 

[RJinTexas]

Remington still produces 7mmBR brass. They chambered the XP100 pistol in 7mmBR it was fairly popular with the silhouett shooters some time back. And yes as you'd expect it's an inherent accurate cartridge like all it siblings.

Regards
RJ

 

[DHD]

Why that is such a good idea that someone beat ya to it by 20 + years ;D. Like stated above, the XP-100 crowd have used it the whole time. If not completely mistaken, the 7mm was first then the 6mm BR.

It is a very good idea though!

 

[Laurie]

Yes, very much a single-shot pistol cartridge these days, and you'll nearly always find it in the pistol loads section of reloading manuals. Odd how it didn't take off as a rifle cartridge given it has a longer SAAMI COAL than 6mm Rem BR and faster rifling twist. Presumably just too small a case to attract 7mm rifle users, so that 7mm-08 Rem became the smallest acceptable cartridge in the calibre.

Incidentally, if you look up the late 1940s / early 1950s British military contender for the postwar NATO universal rifle cartridge - variously known as the .280/30, 7mm British, 7X43mm - on the 'Web', you'll find that British ordnance technicians got there 20 years before Remington. The 7X43 is a dead ringer for the 7mm BR except for having a steeper body taper and more shallow shoulder angle, both deemed essential for good magazine feed in automatic rifles. It gave a 140gn FMJBT bullet quite respectable MVs for the time, around 2,400 fps if I remember right, and was briefly adopted as the standard UK service cartridge alongside the EM2 'bullpup' assault rifle in the early 1950s, but was overtaken by the adoption of the US 7.62mm NATO to die completely.

There's nothing new under the sun, as they say! If it had been adopted by NATO, the 7mm BR or something very similar such as a .280/30AI would be a major sporting and target rifle cartridge today without doubt. There are many other odd omissions in rifle cartridges too. P.O. Ackley wrote that the 308W necked down to .270 cal made a superb medium game cartridge, a very accurate and effective killer with light recoil, yet this calibre and wildcat is the only one missing in the lineup based on the 308 case despite Americans' love of the calibre. Presumably, Remington and Winchester believed it wouldn't compete sales-wise with the existing and much higher velocity .270 Winchester.

Laurie,
York, England

 

[2644ever]

About 10 years ago, I had a Savage 110 fitted with a 26" Hart int that caliber, as I didn't foresee a huge velocity difference with the 7-08, I kept the same 1 in 9.5" twist. With Nos BT's in all weights, Sierra 130 Mkg's and 150 Mkg's, and compressed charges of N540 and N133, the rifle was extremely efficient and accurate and would roughly duplicate the ballistics of the .308 Win up to 800 yds with 16 grains less powder. I wish I had "dasherized" the case and used a 30" barrel, but this is a project I will tackle before I'm too old. Unless I switch to a 6.5 BR with the same improvements... Oh well...

 

[Laurie]

With Nos BT's in all weights, Sierra 130 Mkg's and 150 Mkg's, and compressed charges of N540 and N133, the rifle was extremely efficient and accurate and would roughly duplicate the ballistics of the .308 Win up to 800 yds with 16 grains less powder. I wish I had "dasherized" the case and used a 30" barrel, but this is a project I will tackle before I'm too old. Unless I switch to a 6.5 BR with the same improvements... Oh well...(2644ever)

That's an interesting thought - a dasherised 7mm BR. What sort of MVs did you get with the standard case?

Laurie

 

[2644ever]

I could get 2800 fps with the 120 Nos BT molycoated and 2700 fps with the Sierra 130 Mkg. Compressed loads of N133 in both cases. Actually the Nosler 120 grainer has a better bc than the Sierra 130, and makes the 7 BR the equivalent in trajectory and wind deviation of a .308 firing a Sierra 155 or a Sierra 168. Very efficient little cartridge.

 

[CJ6]

Sierra lists loads for both Rifle/Pistol 7mmBRs. If you need some 1x fired RP 7mmBR brass let me know.