358 YETI

[wquiles]

I got one 35 cal rifle, my custom mauser, but I wanted another 35cal rifle. Although a lever-action sounded appealing, being honest with myself I have never "loved" lever actions that much (I still have an original Marlin in 45-70 and it does not get much use). After evaluating several options, I decided on the AR platform. Having both an AR15 (300BLK pistol) and the AR10-style in 308Win, I decided I wanted/liked the smaller and lighter AR15 frame/parts, and after much reading, I settled on the 358 YETI:



I ordered parts last year over a 3-month period to spread the cost of the build, specially since I went for a non-reciprocating side-charging upper for this build:



Like with my other builds, I have settled on ONE suppressor mounting system, so I enlarged it to about .4":



Here is a close-up of the bolt with the different piece to engage the side charging handle:




This upper also has a cover in the back, which of course when "up" allows removing the bolt, but then down blocks gases from hitting you on the face:




Finished built weight minus optics:

 

[wquiles]

Size comparison: 308Win (18" barrel) on the left, 358 YETI (16" barrel) on the right, both with my Ti form 1 suppressors



Here comparing the 358 YETI on the left, with my 300BLK pistol on the right:



Current configuration:

 

[popper]

The upper beefed up due to left side cutout? I like the idea of the non-rec. handle - hard to use?

 

[Spindrift]

Very nice! The Yeti is certainly an interesting cartridge. Are the reloading tools readily available, or are we talking special order, sell-a-kidney tools?

Looking forward to hearing more about this interesting gun! Best of luck!

 

[wquiles]

The upper beefed up due to left side cutout? I like the idea of the non-rec. handle - hard to use?

Looks plenty strong - more photos here:
G4 Side Charging Upper Receiver

I have only played with it at home, but so far not hard to use. I did lightly sanded the surfaces a little though, still a little "sharp" from the CNC to me

Very nice! The Yeti is certainly an interesting cartridge. Are the reloading tools readily available, or are we talking special order, sell-a-kidney tools?

Looking forward to hearing more about this interesting gun! Best of luck!

I have been working yesterday and today on making brass, out of LC 308 brass. Photos later today

 

[wquiles]

Reloading tools, custom 2-die set from Hornady ($90, available from the same vendor who sells the barrel and matching bolt head), so the real work is to make the brass itself. For the brass, the designer used LC brass as a starting point, and he provided a headspace range (which I tested in my rifle/barrel), and a target length of 1.646".

Since that target length is to be measured after sizing on the Hornady sizing die, I had to experiment "where" to cut the 308 LC brass a couple of times to minimize the amount of time spent trimming to final length (1.646").

Since my lathe has a DRO, I used it to do the cutting:



My first batch was too long:



This one I cut too short:


As after sizing was under the target length:



Eventually I got to this range:


Which after sizing came close (but over) the target, so that I can trim to final length:

 

[wquiles]

I of course have to clean up the edge in between operations:



Used this lube when forming the cases:



Trimmed length close to target:



And with this headspace my bolt closes easily:



Once I had the "setup", I did the initial cut for 110x cases this afternoon on the lathe:



Now I have to clean up the edge, size/form, trim to final length, clean up edge one last time, and then I am ready to try a few dummy rounds. Once I get those to function/feed properly, I can prime this cases and make my first rounds to try out

 

[Brad]

Why not push shoulder back fort then trim neck? That is what I do in cases like this. Only do the deburr thing once.

 

[wquiles]

Good idea Brad. I honestly didn't think about it, but I will try for the next batch

 

[Brad]

You could also bore soft jaws to hold the case. Leave a shoulder on back end to locate the head of the case. Lock the carriage and it becomes a routine cutoff. Cut a little long and trim to final length on case trimmer.

I made soft jaws from round pieces of Al stock with a hole for the bolt that attaches to jaw in chuck. You could get by with 3 pretty easily.

 

[Ian]

Definitely knock the shoulder back first, then cut off. Twist the mouths on a case lube pad to get a hint of lube inside and out since you'll be having to force open the .30-caliber neck.

 

[Ian]

I've made enough wildcat brass to be well sick of it, hopefully you find it more enjoyable than I did. I think if it were me I'd just build another LR-308 upper and put a KAK .358 Winchester barrel on it. .473" case heads in AR-15 magazines can be fussy.

 

[JWFilips]

And this cartridge will do what? Just wondering what it is supposed to do? Seems like a lot of work for ?

 

[Hawk]

You may need to anneal and neck ream.
I made a bunch of 7.62x40 WT and had a problem with the neck thickness.
Outside neck reaming cured the problem.

 

[popper]

Guy that did the bo cut jig might make one for it. I'd form sholder, anneal, cut neck then expand. 200-220gr @ 2k fps. Same powder as bo. That upper is high $. You modify the hand guard? Taht upper stated it doesn't work with some aligning hand guards. I payed with making BO brass by first trying to expand, then tried cut neck & expand. Always got neck splits. Guy that 'invented' it must have wanted as much powder space as possible so the funky length vs cutting athe shoulder off. RC he developed on Savage, then had special bolts made for AR, thicker on the rim.

 

[wquiles]

Yes, I cut the handguard to just cover the adjustable gas block. Good reloading data available from others. Looks like AA1680 and Shooters World Blackout powders deliver good results.

Using 6.8 mags, which suppose to work/feed well for this cartridge, although I believe some Lancer mags also work "as is". Still an area I have not done work yet.

Considered the KAK .358 Win barrel, but wanted lighter/smaller.

The jaws on my lathe actually have some internal grooves that "perfectly" match holding the case in the same spot (within a few 0.001") so I got lucky and no need to make soft jaws nor a stop.

My first wildcat. Still learning, thanks for the suggestions

 

[fiver]

remember your likely to have some case length shrinkage when you fire form them.
body stretch and length shrinkage all in one fire form session, what's not to love.

you'll probably end up cutting some metal out of the necks when it's all said and done so that's something I'd watch for.

 

[wquiles]

fiver - you mean I might need to do a little neck turning? if yes, wait until after I get the fire-formed brass?

 

[freebullet]

Neat project, thanks for sharing!

 

[Ian]

Might pay to slug the bore with a soft lead slug or make a pound cast that is long enough to get into the rifling. That way you know what the actual groove diameter is, and what the throat entrance diameter is. Make a bullet a couple tenths smaller than throat entrance diameter and seat it in one if your prepared cases, then measure the neck OD and compare to your pound cast's neck diameter (making sure you fully annealed and "bumped" the neck of the cast) to the dummy round. You want at least a half-thousandth total clearance, 1 to 2 thou is better. THEN you will kbow if you need to outside turn your necks.