6mmPPC AI...?

[DavidBoren]

I'm looking for a 6mmPPC with a per caliber neck and a 40 degree shoulder. From my quick calculations, this puts the neck to shoulder junction at 1.2602" and the base of the shoulder at 1.1592" or thereabouts.

Does this already exist? I haven't been able to find a list of 6ppc based wildcats and their dimensions.

 

[Tim Singleton]

Sounds real close to what Brett, Dean Stroud and Bart Sauter have been shooting
They call it the 6mm Grinch

 

[DavidBoren]

Thank you for the response, Tim.
I have seen the 6mm Grinch and it is almost exactly what I am looking for, except for it not having a per caliber neck, which is something I desire.

 

[Eddie Harren]

Thank you for the response, Tim.
I have seen the 6mm Grinch and it is almost exactly what I am looking for, except for it not having a per caliber neck, which is something I desire.

Please tell me what a "per caliber neck" is.

 

[DavidBoren]

The caliber of bullet, in this particular case, is .243" and thusly I want the neck to measure .243" in length.

The Grendel has a neck which measures .235" or something like that, so it is already too short to meet my criteria.

The PPC has a neck that measures .284" or close to, which is longer than I need.

 

[Eddie Harren]

I would send your drawing to JGS, Manson or PT&G and have a reamer made. That way you would get exactly what you want. Then all you will need is some suitable brass that will end up as long as you wish, after forming and fire forming.

 

[gunsandgunsmithing]

The caliber of bullet, in this particular case, is .243" and thusly I want the neck to measure .243" in length.

The Grendel has a neck which measures .235" or something like that, so it is already too short to meet my criteria.

The PPC has a neck that measures .284" or close to, which is longer than I need.

If you desire a very specific neck length, you'll very likely have to trim the necks to that length. Although, If I were doing it, I'd not worry about the neck being a few thou longer. I'd just spec the reamer based on my resultant neck length and call it good. Of course you could, spec the chamber reamer with the shoulder position at such a point that it yields your desired neck length.

Sounds like a lot of trouble for little or likely no gain.

I'm shooting a 6 Grendel, which is a .070 long PPC and has a chamber neck length of .2386. It shows a lot of promise and is simply a necked down 6.5 Grendel. The Lapua brass for it is great.

 

[DavidBoren]

Yes, I am looking for something with the shoulder moved forward to give me the desired neck length. No, I do not want to simply trim the neck to a specific length.

From my calculations, using the 6mm PPC case, the neck shoulder junction moves forward .0397", to 1.2602" from case base. And the shoulder itself moves forward .0844", to 1.1592" from case base. This gave me a .243" neck, and a 40 degree shoulder angle, according to the model I threw together in Acad.

My question is if someone has already done this, given it a name, and made reamers for it. Because I would rather make exactly what I want, rather than just settling for the 6 Grendel/Grinch.

 

[gunsandgunsmithing]

Yes, I am looking for something with the shoulder moved forward to give me the desired neck length. No, I do not want to simply trim the neck to a specific length.

From my calculations, using the 6mm PPC case, the neck shoulder junction moves forward .0397", to 1.2602" from case base. And the shoulder itself moves forward .0844", to 1.1592" from case base. This gave me a .243" neck, and a 40 degree shoulder angle, according to the model I threw together in Acad.

My question is if someone has already done this, given it a name, and made reamers for it. Because I would rather make exactly what I want, rather than just settling for the 6 Grendel/Grinch.

Pick up the phone and call the reamer maker of your choice. There are only a few that make probably 99.9% of all chambering reamers. If anyone would know, they will. Regardless of if it's been done and named, tell them what you want. They will probably know if it's been done and what it was/is called, and be very capable of making a reamer, by their prints or by yours. Enjoy, but I don't think using a Grendel or living with a few thou different neck length is "settling." If it is, IMHO, it will not be because one or the other shoots better or worse, but rather, because you want what you want. That's good.

If not mistaken, what you want is a 6mm Grendel AI. You might have to fire and size the brass a few times to get it to stretch to you're desired length...which is a whopping .0045" different from the 30° parent Grendel shoulder angle, that I mentioned. But of course, the brass will probably shorten another thou or so moving the shoulder to 40°. Then again, your overall brass length will change, depending upon your fire forming method.

You asked. You didn't like what I had to say...so do it however you want it to be. That's the beauty of a wildcat. Maybe the 40° shoulder is worth it...maybe not. There are pro's and cons to forming brass. Stress on the brass being one of them. Barrel life is another. Dies are yet another.

Personally, I like easy, when it works just as well.

Good luck and keep us posted. I'm sure that what you have in mind will do just as well as anything that's easier and already out there...perhaps better.

 

[DavidBoren]

PTG is relatively local to me, and I hadn't thought of calling them. They would definitely know if they have ever built a reamer to those specs.

I used a 300WM for a couple years, reloaded for it, hunting mostly, and I didn't find its short neck to be an issue. So I'm not dead set on the per caliber neck, I just am trying to see if it is a consideration or feature someone else has already done with the 6mm PPC case. I'm actually looking for something that is already out there so it is easy and more readily available.

The Grinch and the 6mm Grendel are both very close to being exactly what I want. And it is proven by people who have forgotten more than I will ever know. I apologise if I came off as ungrateful or stubborn.

If I do decide to get a reamer built to my specs, I will have some Lapua brass hydroformed to the reamer dimensions to get me started.

 

[DavidBoren]

If I do go with a custom reamer... When fireforming or hydroforming, is it easier to start with a 220R case and push the shoulder and neck shoulder junction forward, or start with a Grendel case and push the neck shoulder junction backwards and the shoulder forward?

By my calculations, the case I am proposing should actually offer more case capacity than the Grendel/Grinch, because my shoulder is .0136" farther forward. Not that it matters, as I am not really trying to increase powder capacity, I mainly just want a per caliber neck and 40 degree shoulder angle, any added case capacity is simply a bonus.

 

[Ghansen]

if your case shoulder is .0136 further forward than a "Grinch", I don't see how you are going to attain the neck length you are looking for.

 

[DavidBoren]

I made a virtual model in Acad to achieve the measurements, and I feel the model is accurate. I maintained the PPC case taper, placed the neck shoulder junction to give me a per caliber neck, and then I moved the shoulder forward until I had a 40 degree shoulder angle.

I am proficient in Acad and I trust the measurements derived from my model, but I also don't have access to the exact external dimensions of the Grinch, so I cannot comment on that with complete certainty. My cartridge will have the shoulder moved forward compared to the unmolested 6.5 Grendel case. I know that the Grinch is based on the Grendel case, but I don't know what changes were made other than the generic description on Bart's bullets website.

 

[Rtheurer]

Have you looked at the 6mmFat Rat and the 6mmTurbo 40? And the Grinch... All about the same in terms of Performance I am willing to bet.

 

[Brett S]

I made a virtual model in Acad to achieve the measurements, and I feel the model is accurate. I maintained the PPC case taper, placed the neck shoulder junction to give me a per caliber neck, and then I moved the shoulder forward until I had a 40 degree shoulder angle.

I am proficient in Acad and I trust the measurements derived from my model, but I also don't have access to the exact external dimensions of the Grinch, so I cannot comment on that with complete certainty. My cartridge will have the shoulder moved forward compared to the unmolested 6.5 Grendel case. I know that the Grinch is based on the Grendel case, but I don't know what changes were made other than the generic description on Bart's bullets website.

 

[Brett S]

View attachment 1012789

Here is a picture of my little Grinch which is close to what your looking for.

 

[South Pender]

Just a simple question from a guy who's far less expert than most on this forum: Does the neck length really matter that much? Here's why I ask: The Wilson chamber-type neck-sizing die that I use only sizes down the last .1875" of the neck, stopping well short of the shoulder while still providing plenty of bearing surface for bullet/neck contact. This leaves some of the neck (about .10") expanded, which I assume improves the centering of the case in the chamber.

 

[gunsandgunsmithing]

IMO it does not. That said, the op stated his desires and beliefs differently. Stan Ware either shoots or did shoot his 30 Wolfpup, which has nearly no neck at all and has done very well with it. FWIW.

 

[Brett S]

IMO it does not. That said, the op stated his desires and beliefs differently. Stan Ware either shoots or did shoot his 30 Warewolf, which has nearly no neck at all and has done very well with it. FWIW.

The only benefit of a longer neck that I see is it's not so freebore sensitive. IMO

 

[gunsandgunsmithing]

The only benefit of a longer neck that I see is it's not so freebore sensitive. IMO

I'm not sure if it is or not. Here's an article with pics. I misspoke earlier. He calls it a Wolfpup, not a Warewolf. I changed it in my previous post.
http://bulletin.accurateshooter.com...al-short-necked-wolfpup-for-hunter-benchrest/