The 270 Boondoggle gets boondoggled

[yorketransport]

After the unexpected complication of having my reamer break, I've been forced to rethink my 270 Boondoggle project. The initial plan was to just go with the 27 Nosler as my backup and be done. After going back and forth with the smith we decided that instead of doing a SAAMI spec 27 Nosler, the 27/28 Nosler would be more interesting since the official 27 Nosler is actually a shortened 30 Nosler which is shorter than the 26 and 28 Noslers. Going with a 28 Nosler necked down to 27 would allow for either 26 or 28 Nosler brass to be used and would just mean running a 27 Nosler reamer about .060" deep.

Today I got an even better idea! Now I think I'm going to push a 27 Nosler reamer in .167" deep and use a 338 RUM headspace gauge. This would give a full 10gr case capacity increase over the 27/28 Nosler and a nearly 17gr increase over a factory 27 Nosler. The only change is that I would use 338 RUM brass instead of Nosler brass. That opens the door for a couple other brass options since I can form 338 RUM brass from any of the RUM cases and I happen to have almost 200 pieces of 7mm RUM brass sitting around.

This is a 27/338 RUM case loaded with a 168gr Hammer Hunter at 3.680" next to a 27/28 Nosler case (formed from a 7mm RUM case). The shoulders are a little "soft" because of the case forming.

[NWShooter]

That will work. That shoulder angle should give you a better powder selection and not jam you up with US869.

[BULLBLASTER]

Why not a 270-7mm rum?

[NWShooter]

The .338 RUM is slightly shorter than the 7mm & 300 RUM. With the longer higher BC bullets such as the Hammer's and Matrix. COAL fits standard long action mag boxes better along with CIP length AICS mags. As compared to the the COAL when it comes to the longer  7mm / 300 Ultra case with the longer heavies.

[yorketransport]

Why not a 270-7mm rum?

Because I already had one. 

[Jolten]

Badger 2.0???

[NWShooter]

Badger 2.0???

Possibly...... Bunch of sicko's😷 But then again a guy only needs a .270 Win or a 06. Uuuuuuh OK.

 

[Reidus]

How does that affect the base diameter in the chamber when you run it in 0.167" deeper? Couple thou bigger at the base?

[Dan-o]

Good grief man......

I'm almost surprised you're not building it in a revolver.

Expected velocity with that Hammerhunter?

[bearpaw]

Good grief man......

I'm almost surprised you're not building it in a revolver.

   looks pretty interesting though

[BULLBLASTER]

Why not a 270-7mm rum?

Because I already had one. 

Makes perfect sense.

I can also see the mag box reasoning

[jasnt]

That’s going to be fun

[yorketransport]

How does that affect the base diameter in the chamber when you run it in 0.167" deeper? Couple thou bigger at the base?

Yes, the chamber ends up slightly "fat" at the base. It's not an issue and can actually help prevent the "click" at the top of the stroke when opening the bolt. I use 404 Jeffery brass in my RUM based 375 BME and 8x68s brass in the 338/375 Ruger and essentially end up with the same condition only I'm using slightly undersized brass instead of a slightly over sized chamber.

Badger 2.0???

I thought about just using a 6.5 Badger reamer with a 270 pilot bushing and then cutting the neck/throat with a 270 reamer. After playing with the Badger a bit, Biggerhammer (LLBH ) and I both think that making the shoulder angle a bit shallower would help allow more powder options. The sharp shoulder and small bore diameter on the Badger makes US869 the most usable powder to prevent powder bridging, the problem is that US869 has pretty dramatic temp swings.

Good grief man......

I'm almost surprised you're not building it in a revolver.

Expected velocity with that Hammerhunter?

I have 2 barrels getting chambered, a 25" and a 28". The goal is to hit 3300 fps with the 168gr Hammer Hunter from the 25" barrel and get closer to 3400 fps in the 28" barrel.

If it all works out this would be a pretty neat "entry level" high performance wildcat for guys who don't want to do a lot of fireforming or buy custom dies. Cases can be formed by necking down 338 RUM brass in either a 300 SAUM or 30 Nosler die, then running them into a 27 Nosler die held off the shell holder enough to just bump the shoulder on the case. The shoulder angle and diameter will change slightly after the first firing so they match the Nosler case but not enough to make a significant difference in case capacity. ADG makes 338 RUM brass or its very easy to form 338 RUM brass by running any of the other RUM cases into a 338 RUM full length sizing die with the decapping assembly removed. If you do that you just have to trim the cases back a little bit more.

Now I just need to convince the smith doing the work that this is a good idea. I've encountered a lot of folks who don't like my approach of mixing different reamers and headspace gauges. What's the worst that could happen when you intentionally cut a chamber with .167" excessive headspace?

[NWShooter]

Looking forward to the end results. Hammer bullets is a solid choice considering the speeds your running. They should perform well on porcupines, black tail and those nasty, mangy West side bears.

[Jolten]

#LLBH!! Btw I'm still waiting for you to redo that HPBT gameking bullet trap that you blew up