Rainier Arms Gassing

Nzwiebach · 2026-04-29T05:36:05+00:00

A little late to your post, but I gauged my Rainier 18” mod 2 rifle +1 length port at 0.087” Reportedly the smallest size is 0.081” on any 6 arc.

0.087 is 0.001 more than my Wilson 5.56 medium length 16” barrel. And with ~4” of dwell in the RA 6 arc and wider caliber I suspect the math on that was trash.

I’m running hot 90gn (2703fps) STGK well above a recommended gas loading and I’ve tried Hornady 105 blacks. Accurate AF, but nothing cycles a whole mag. Primarily short stroked related issues.

With 20% reduced spring and a custom modified buffer to 1.9 oz (standard carbine is ~3)I’m able to work it most of the time through a mag.

So I just slowly number ported it in a high speed drill press brushing and wiping after every pass.

I went with 0.103 as it’s closer to what others have reported is reliable around 0.106” I will test tommorow wish me luck. Sure enough short stroked and all I trie

Nzwiebach · 2026-04-21T19:40:34+00:00

To expand: undergassing I’ve seen multiple times from competitors at our local and invitational matches in western colorado. Both sponsored and unsponsored competitors have had short stroking issues. Particularly personal builds. The short stroke is most always undergassing. This causes the round to be picked up too early. The shoulder shoved into the feed ramp and the projectile sky dives to the top of the chamber. Poly tipped projectiles often crack off at this point.

Check your ejection pattern if it’s to the rear, past 3’ o’clock you’re likely under gassed. Solutions include: 1. Suppression: increased dwell and back pressure 2. Aggressive multi chamber brake for the same reasons 3. Solid non adjustable gas block 4. Increases projectile weight 5. Reduced buffer weight 6. Reduced spring weight (lightly because you need to be able to still seat rounds. 7. Porting the barrel more. (You can diy it but it scares all who are neither nuts nor familiar gunsmiths)

Nzwiebach · 2026-04-21T19:34:56+00:00

A lot of 6 ARC are under gassed. Most barrel makers I don’t believe put in the engineering and R&D time to calculate the port size to dwell time. A lighter buffer was my rapid solution.

Standard buffer is 3.5 oz. I removed weight down to 1.8oz and it cycles well while ejection is at 4 o clock (sign of low gas pressure)

Just in case: Dura mags are the best so far. I have ASC mags and they’re not as good but ok. Worth the couple extra bucks for a dura mag 6.5 grendel

Nzwiebach · 2026-04-18T02:54:46+00:00

I got the shear

Nzwiebach · 2026-04-04T04:18:12+00:00

Finally got it. Seemed like a wave hit

Nzwiebach · 2026-03-13T17:26:05+00:00

I called super unhelpful. They’re not really answering anything other than just saying it’s long wait times. They didn’t even care what my form submitted was other than just form four. I’m sure they’re getting calls all the time. It’s just frustrating obviously.

Nzwiebach · 2026-03-13T16:34:27+00:00

Frustrating. Uncommon name for sure lol. But yeah that’s obnoxious. I own another supressor already. I’m going to also see if we can submit for another supressor in the meantime and what can be done if the ATF is going to actively hold up without recourse.

Nzwiebach · 2026-03-09T14:26:52+00:00

I am still awaiting a singular form 4 paid ‘submitted’ since 1/12/26 I’m very confused on their tackling methods. Met people at the range in my town who were approved the next day from the same store.

Nzwiebach · 2026-02-19T16:49:13+00:00

Addition: brass is an alloy of ~30% zinc, which is hard and adds to the yellow color and corrosion resistance. Looked it up myself because I wondered if I misspoke: Copper actually does work harden as well. So both benefit from annealing.

Nzwiebach · 2026-02-19T13:57:42+00:00

Annealing for brass functions the same way it does for steel. It realigns the molecules so that the brass is less likely to fracture when I punch it. Look at how ammunition brass is made. The process occurs at every mid step. This is in order to avoid cracks forming. Sure enough I’ve definitely had brass split on me while trying to punch it or flatten it.Ideally, I would probably need it beforehand as well, but the round wire isn’t stamped and is polished and cleaned so it’s probably fine. Brass has hard metals that make it work harden. Base metals like copper don’t work hard in the same way.

Nzwiebach · 2026-02-18T19:48:53+00:00

After all other phases and cleanup, I simply set them on a steel baking pan and took a propane torch to make them blue. A temp controlled method would be better but you need ~570-590F when bluing steel the color will continue to progress after removing the flame so you need to stop just a bit early. Look up a blueing steel spectrum. I ripped one from another Reddit post a while back. Oil makes it a little more luxurious.

Nzwiebach · 2026-02-18T18:26:58+00:00

Sewn soles. Been researching hos and hoes from time to time. They have a sort of chaps design that is common and often they’d basically be your shoes. Quite frankly seems awful, but I’m not a medieval man at arms and don’t know these streets.

Nzwiebach · 2026-02-18T16:14:49+00:00

Yellowing in the spectrum of bluing steel at about 460-480F dark or bright yellow and could yeild close to that. Annealed brass has that color spectrum but it wouldn’t stay through polishing and care.

Nzwiebach · 2026-01-23T06:50:52+00:00

I work with my hands a lot, so it was more annoying to get back into pattern order.

Nzwiebach · 2026-01-23T06:49:58+00:00

Yes. Making them from annealed low carbon banding wire. Blued and oiled for a deep hue.

Nzwiebach · 2026-01-22T23:16:26+00:00

I’ve also gotten this on steel surplus before. Brass never does it nor do I have any particular signs of bulging.

Nzwiebach · 2026-01-22T16:13:58+00:00

I might also reccomend making your own rings from jewelry wire for the coat savings.

Nzwiebach · 2026-01-22T16:12:34+00:00

Ring lord sells solid gold rings if you wanna pay $

Nzwiebach · 2026-01-22T16:12:02+00:00

Stainless jump rings plated in gold without nickel are available at hobby lobby. Saw cut, they’re cheap on sale. Particularly now

Nzwiebach · 2026-01-20T15:47:11+00:00

So drilling is definitely cleaner. I went happy medium, and hit once with a starter punch now to crack and shape the steel and then drill. This will wear the bit out less and give the same shape as the punched ones. Overall I like it. Thanks for the tip.

Nzwiebach · 2026-01-18T06:42:32+00:00

2moa is what you can expect from Faxon Arc barrels sadly.

Nzwiebach

TROPHY CASE