Thinking about building a 7mm. have some ?'s

[Forum Boss]

Looks like with Reloder 17 you can take a straight .284 up to 2980 fps or so with the 180 Bergers and a long barrel. Whitley just emailed me that he was able to get his .284 to 2950+ easy with Winchester-headstamp brass, CCI primers, and RL17.

 

[flatlander]

I've got a couple of straight 284s, and have had very good results with Berger 180 VLDs out of both at 1000 from the very beginning of load development. The std. 284 already has minimal case taper and a 35* shoulder, so the Ackley Improved version wouldn't yield nearly as much increase in performance compared to what you'd get with the AI version of cases like the 6.5x55 or 250 Savage, which have a lot of taper and shoulder angles of less than 30*.

Velocity with H4831 maxes out at just over 2800fps in both my 30" bbls. - one a Bartlein, the other a Krieger, both 9-twist. Robert Whitley reported getting velocities up to 3000fps with RL17 in his 284 - I'm looking forward to getting a couple of jugs of this powder and looking for an accuracy node in the 2900-2950fps range. That's about all the recoil I want to deal with without a brake, and since most of my shooting with the 284 is in NRA LR HP matches where brakes aren't allowed, recoil is definitely a consideration - as is barrel life. That's two good reasons I plan to stick with the 284 instead of either one of the short magnums.

Both my barrels were chambered with a no-turn neck version,.318" neck vs. .315" on Robert's) of Robert Whitley's reamer, which works very well with WW cases. Robert has used both Lapua 6.5x284 necked up & WW with this reamer.

 

[JHardy]

Im thinking about a future project gun in a 7mm caliber to shoot the 168 - 180 grain bullets. I can think of a few different cartridges to do it with. Ive thought about necking up a 6.5-284 to 7mm, and even doing an improved version of the 6.5-284 in 7mm. The other choices are either the 7mm WSM or 7 RSAUM.

Between the 7 WSM and RSAUM. which would be the best choice? Ive seen alot more WSM's than Ive seen RSAUM's. Both will produce about the same velocity. Would the RSAUM with the longer neck be the best choice? And what about the 6.5-285 improved in 7mm?

Thanks Jerid

You don't have to go to a 7 WSM or RSAM to get the accuracy and fps you want. I shoot what amounts to a 284 Shehane, which I refer to as the 284 JCX, which is based on the 6.5x284 case. I do not improve the shoulder which is already 35 degrees. The JCX simply has less body taper than the straight 284. When fire formed, the neck is not sucked in even shorter as would happen in an AI version, for example. My ff cases are .485 at the shoulder compared to about .474 on the virgin case. Simple and efficient.

I can run 3000 fps easy with H4831SC and Russian primers but I keep it to 2950 to 2975 because that gives me what I need with the 180 Berger VLDs, meplats closed,.684 BC + closed meplats will give you a BC somewhere over .700) in all weather conditions. I shot this load at the long range Regional at Camp Butner on the weekend of June 7th when the temps were between 103 and 105 in the shade. I had no hard bolt lift. I blew no primers, and my prone/sling groups showed me no vertical, and all shots were on call. Of course, with the Shehane/JCX you have the advantage of Lapua brass.

The bottom line is that the Shehane/JCX will do everything that a WSM or RSAM will do with less powder and better brass -- with a standard bolt face. If I thought there was something better,IMHO), I would be shooting it at long range.

BTW, after Robert's testing, I have 20 lbs of RL-17 on order to ship next week. If it gives me accuracy and temp stability like H4831SC, then the JCX will get even better -- very quickly. It is exciting to see Robert getting 3003 fps with the standard case since the JCX will do that without RL-17. I can't wait!

Just my $.02,
Jim Hardy

 

[BlackHawk95]

JHardy,

I really like the sound of the JXC. I could use the rifle I have now, and not have to change anything. Would you happen to have any pics of a loaded round?

Also, from what Ive read, the RE-17 sounds like really good stuff. Of all the powders Ive tried for my .243AI and 6.5-285 RE-22 does a great job. I shot My 6.5-284 at 200 meters this weekend with 52gr RE-22 and shot some of my best groups so far at that distance.

Jerid

 

[mattdienes]

I'm quite suprised no one mentioned the 280AI,you have nice dies and brass availible and also good barrel life .It doesn't give up much vel. to any of the other 7's and is easy to make shoot.

 

[Bolo]

The 280AI and the 7RSAUM have almost identical case capacities. But the SAUM is more efficient without fireforming. I'll stick with the SAUM. If I were a better trigger puller, it would have won me alot more fake wood.

Steve