how much shoulder is needed for headspacing?

[RU shooter]

I was reading my COTW book and read about the 400 whelen saying it didnt have enough shoulder to properly headspace ,So how much is enough? I was spending some rainy evenings toying with necking up some various cartridges,An interesting outcome was the 7.62x39mm I necked up to 35 cal. Cute little thing that almost mirrored a scaled down 35 rem.
Problem is the shoulder is very slight only approx.012 difference from the neck dia. In comparing it to the 35 rem.case it seems like a partial pass with a 35 rem reamer into a 39mm chamber and a fire forming might work. comparing case length and capacity it would be close to if not besting 357 max. performance. the 7.62 actually operates at 2K higher pressure than the 357 max. That would be a neat conversion to have a semiauto 10 shot 357 maximum(think SKS) or the same for a bolt action by just reboring the barrel to 35 cal. Would turn the 7.62 Soviet into a real thumper! Call it the 9x39 or the 358 auto max.:razz:Well how nutz am I?

Tim

[Ricochet]

If it catches on, after a while someone'll come up with the great idea to neck it down to .30 caliber!

[dragonrider]

Straigtening out the taper on the body of the case to a minimum taper may provide you with more shoulder, but it may also reduce the lenght of the neck, I think it would be worth a try. I wouldn't mind having a barrel in that caliber for my TCR 87.

[BarryinIN]

Don't the Russians have a 9x39 they load with heavy bullets to subsonic velocities for suppressed shorty AKs?
I don't know if it's a necked-up 7.62x39 or it just happens to have a 39mm long case and is used in AKs.

[BarryinIN]

Found it.
http://pookieweb.dyndns.org:61129/Groza/9x39/9x39_info.htm

Based on a "necked up and blown out" 7.62x39. So if it that description is accurate and it is blown out, it will have more of a shoulder.

Sounds like a fun round, actually.

[RU shooter]

Looks alot better with a serria 200 gr RN seated in it. I guess it is true "theres nothing new under the sun" Drat foiled again!:sad:
16298

[badgeredd]

Looks alot better with a serria 200 gr RN seated in it. I guess it is true "theres nothing new under the sun" Drat foiled again!:sad:
16298

RUShooter,

So happens that James D. Mason wrote up the conversion in September 1993 Guns % Wammo for use in a mini 30. It has intrigued me ever since. In his article he shot the Hornady 200 RN at 2076 fps with remaining velocity at 100 yards of 1650 fps and 1208 ft. pounds of energy. Yep I also think it is a cute little cartridge. He did blow out the case a bit. BTW it is nearly a duplicate of the 35 Rem factory loads.

Edd

[Bret4207]

From what I've read, never having owned a 400 Whelen or any other cartridge with a minimum shoulder, proper fireforming with a nice soft annealed case can make quite a difference in the effectiveness of the shoulder. Cartridge brass has a fair amount of spring back, more as it work hardens. So by using a soft case when you fire form you get a more complete shoulder and less problems with fail to fire which seems to be the main issue with the minimum shoulder.

FWIW- I do use the 35 Whelen and 35 Remington, both supposedly with inadequate shoulders, and I've never had any issue related to that.

[StarMetal]

Read this:

http://forums.accuratereloading.com/eve/forums/a/tpc/f/3221043/m/828107597

[rockrat]

Over on AR15.com, it has been discussed and someone actually came out with a version of that, less taper on the body, and had dies made. I bought a 35Rem reamer and dies, to short chamber an AR15 barrel and make a kind of 35Rem short, using the 7.62 x 39 case. Mags are the problem.
Also made a 44/284 and IIRC, only had about .015" shoulder. Worked fine out of an XP100 and the one rifle I built.

[StarMetal]

Over on AR15.com, it has been discussed and someone actually came out with a version of that, less taper on the body, and had dies made. I bought a 35Rem reamer and dies, to short chamber an AR15 barrel and make a kind of 35Rem short, using the 7.62 x 39 case. Mags are the problem.
Also made a 44/284 and IIRC, only had about .015" shoulder. Worked fine out of an XP100 and the one rifle I built.

C-Products make a 7.62x39 magazine now, but their 6.5 Grendel mags work for my 7.62x39 AR15 that I built. Might try one of the two.

Joe

[Freischütz]

There appears to be some question regarding the 400 Whelen's inadequate shoulder. An article in Precision Shooting noted that deviations from the original specifications created the inadequacies. There was a good discussion of this on some internet site – maybe Saeed's.

A range acquaintance of mine was building a rifle based on the correct chamber dimensions. I haven't seen him in a couple of years, so I don't know how it turned out.

[cbrick]

A huge number of 7 TCU's (and 6mm, 6.5 and 30 cal necked up from the 223) have been used, they headspace on the very minimal shoulder with no issues if properly formed and sized after fireforming.

Rick

[nicholst55]

Some guys on the 6.5 Grendel forum are playing with a .35 caliber wildcat based on the Grendel case - a highly modified 7.62X39 case. I forget what they call it. The case taper is reduced significantly in the Grendel, so that probably allows for a bit more shoulder when the case is expanded to .35.

Here it is, the .35 Gremlin: http://www.65grendel.com/forum/showthread.php?p=47075#post47075

[CENTEX BILL]

I am thinking about building a 358 Gremlin (blown out 35x39) on a Savage action as a cast boolit platform. What do you think?

Looks to be a very efficeent cartridge for cast boolits.?

Centex Bill

[felix]

Excellent for 160 grainers. Go for 20 twist. ... felix

[bearcove]

I been thinking about taking the 7.62 X 51 and necking it up to .358. I think it would be a great all arround cartridge for North America. I could probably push a 250gr boolit over 2300 fps. [smilie=l:

[StarMetal]

I been thinking about taking the 7.62 X 51 and necking it up to .358. I think it would be a great all arround cartridge for North America. I could probably push a 250gr boolit over 2300 fps. [smilie=l:

bearcove,

You are right and that is what the 358 Winchester basically is. You may even be lucky and find a rifle in 358 Win and there's dies and brass ready for it too.

Joe

[bearcove]

Yeah, We call it humor where I'm from.

[Houndog]

If I were to try the 35/39mm, I'd use the body and shoulder demensions for a PPC for this wildcat. You should wind up with more than enough shoulder for headspacing and a little more case capacity to boot. A better still round in my opinion would be the 35 BR. Formed cases are available in 6 and 7BR, so necking them up would be easy, and you have the standard 308 bolt face size. I'm considering one of these myself.

[felix]

Yeah, go for the PPC case. ... felix