Introducing Rubin

[StoneHendge]

100 rounds of freshly loaded match ammo. Mmmmmmmm....... Shiny.

   

[BluntForceTrauma]

I love ranks and files of freshly loaded ammo. There's something ... inspirational about it. ;-)

Got some Starline nickel-plated brass in 65G; will eventually get some in 6ARC.

[StoneHendge]

Rubin did not fail me yesterday - in fact Rubin excelled! Match is PRS style for gas guns out to 700 yards, 8-10 hits needed each stage, hit to move on, and max round count of 20 in 90 seconds. Was 3rd in Small Frame and 5th overall (just in front of The Great One - got him by 3 seconds on the timed stage   ) in a total field of 70. Cleaned all stages and was frankly happy just to clean the timed stage since the prop has been a bit of a challenge for me (pyramid made out of 12" corrugated culvert pipe).

73 rounds and nary a hiccup with the Ti carrier (recommended for use with .223/5.56 only) and light weight buffers & spring (Ti carrier not recommended for use with lightweight buffers and springs).Ran one stage up to 17 shots in 90 seconds and I think I did 15 on the timed stage in 70 seconds. The rest were 11-14. Nary a hint of thermal drift - a testiment to both the Lilja barrel and Varget's good behavior. 

Light weight is definitely a plus moving between and establishing positions but potentially the cause of my support bag slipping a bit a couple of times in more precarious positions (such as the tip of a tank trap). GiGi is in the corner of the closet sulking because she has been demoted, but it was a pleasure to not have my bullet magically disappear past 600 yards. 

The nickel brass is brilliant  - only lost one piece which I think is in a stack of sandbags on an embankment. Either that or in the "woodpile" prop. Easy to find and if other shooters find one of the errant pieces, they pick it up and bring it over!

[BluntForceTrauma]

Just checked Starline's website for nickel-plated 6ARC brass — nada.

So I figured I better circle back here and ask if you were sizing down your nickel 65G brass?

[StoneHendge]

Just checked Starline's website for nickel-plated 6ARC brass — nada.

So I figured I better circle back here and ask if you were sizing down your nickel 65G brass?

I did size down nickel 6.5G brass I bought last fall.. Had to wear a glove in order to prevent blistering of my trigger hand while trimming. Starline doesn't make any ARC brass at all - I'm sure they will some day but why bother now. They also don't sell nickel retail. They say they'll do dealer quantities (I think I've heard 50k minimum), but Midway is the only place I've seen it. I've also gotten nickel Starline .357 mag from Larry.

Its a great way to differentiate from my .243 LBC and Grendel brass.  I've got a bunch of nickel 40 S&W too so I don't mix it up with 10mm (wish it was the other way around, but nickel 40 can be had for a nickel in normal times).

[daverx7]

That's a great way of differentiating 6.5 Grendel brass formed down to 6ARC.  I was tempted to get some Grendel brass and use it for the 6ARC, but was concerned about it getting mixed up with the Grendel.  Hmm... a new item to stalk on Midway.

Thanks for the great tip on that, and for sharing your builds.

-Dave

[LaMan]

A simple fine tip sharpie using different colors placed in the brass ejector grove will give you all the differentiation you need until the "chrome" brass becomes available. I have 3 Grendels and a 6ARC, each with a different color.

[daverx7]

I dig that idea, LaMan! In fact to help reduce the possible mixup between my Grendel and 6ARC, I've made my Grendel have a blue charging handle and followers in the mags, and the same in red for my 6ARC.

How well does the marks stay on the brass? Of course I can (and will) test that myself, but if you don't mind sharing your experience with that, that would be great!

Thanks for the tip! (Yeah, I'm a sucker for puns! Sorry...)

-Dave

[StoneHendge]

If anyone wants to get real serious about marking their brass, MKM makes a pretty cool little device.
https://www.mkmachining.com/product/rifle-brass-marker/

[LaMan]

I just place the brass on a nylon bore brush which make it easy to roll 360 degrees with the sharpie tip touching the grove.
I clean with walnut shells, the marking seems to last at least three cycles, and only takes about 5 minutes to do 40.

My daughter and I both hunt with 7x57's which we use the nickel plated brass to separate her rounds from mine. She wanted the "shiny" brass, go figure.

[Old Bob]

When I was shooting a lot of three gun I used to get my 10 round 5.56 mm NATO stripper clips & run a sharpie along the clip marking two sides of my brass. I'd then rotate the brass 180* & mark them again. Some of my shootin' buddies started doing the same thing so we all agreed to use different colors on our brass so we'd know what belonged to who. I used green.

[StoneHendge]

Rubin has put on a little bit of weight, but is wearing it well. Up to about 7.25 lbs.

It all started a few months ago. I had the pleasure of getting the draw to go first on the first stage of a match. At good ole 7am. If there's anyone out there who likes going first on the first stage, introduce me, I haven't met him yet! Prop was a "wood pile" - basically a configuration of railroad ties spiked together. 4 targets starting at ~350 and going to a little over 600 or so. Choose a position, engage near to far, hit to move on, move to a different position an reengage near to far. Simple enough and I cleaned the first 4 in under 30 seconds. Had a bit of a holy crap that was good moment. Take my time and settle into a nice solid reverse kneel in the next more comfortable position. No trigger pull. I rack it. Nothing. Double feed. Drop the mag, clear the round out. Insert mag, close. Hit. Next target. Click. Rack and engage. Hit. 3rd target. Click. Rack and engage. Hit. Last target. Nothing from trigger. Rack and engage (it worked before!) Nothing. Double feed. Drop mag, clear, reinsert, close. Miss. Times got to be running out. Find target again. Nothing from trigger. Rack, double feed. Mother effer! Drop mag onto ground, insert loose bullet into chamber with finger, close, settling on target, BEEP, release, Impact! Timer: 90.45 seconds. A chorus of deflating sounds from the squad. The grace period is 90.30 seconds. 7:05am and no chance of winning. Turns out the screw that holds the gas gate adjustment screw on the adjustable carrier loosened slightly and the gate migrated slightly down and I was under gassed. Simple enough, opened it a little and was a little over gassed for the rest of the match. At the end of the day, the dropped shot only cost me one spot (6th vs 5th) holding all else equal.

Needless to say, my faith in the carrier became diminished and I decided that I simply need to keep on top of it. Since both the carrier and light weight buffers /springs are designed for .223, though, the window between under and overgassed  is incredibly small. 90 degrees on that little screw is the difference between fully opened and fully closed. A touch to closed and the bolt won't lock back. A touch too open and the brass hits the deflecter and flies forward into a cholla.

Worked fine next match. Made sure it was working a day or 2 before and tightened it down. Actually came in second and dropping the 4 seconds or so I needed on the timed stage was all on me. Sprained my hip two weeks later, missed the next match and finally got Rubin out last week for the first time in a month. I was even contemplating using him instead of my 17lb 6.5 CM to keep some stress off of my hip during last weekend's PRS match. Everything was fine - but on my last planned mag at the range, the bolt didn't lock back. Confidence plummets. 

I had an AGB free up and the plan was to put that on and open the carrier gate all the way and maybe then locktite it in place. Started getting ready to install the new gas block and by the time I was done, Rubin had GiGi's JP Low Mass Carrier and Silent Capture spring. The whole premise behind Rubin was to be as light as possible and still be 100% usable. And the confidence in reliability just isn't there with me with the ti carrier and light springs. The SCS does add more weight than a standard buffer and spring, but it is like butter.

Got him to the range this morning to dial in the gas block and rezero (new GB / removed and reinstalled brake). Forgot the proper Allen key for the GB, but zero'd anyways since he was cycling and locking back. Probably some room to dial down, but I may not. Felt recoil is actually noticably reduced. Don't know if that's the extra half pound or the SCS - probably both. Elevation on the zero was good, four clicks to the right and move from the bench to prone for the final dial in and it turns out it wasn't needed:

   

   

Anyone who knows me knows that if I had taken a fourth shot, I would have destroyed the pretty picture. And those RDFs are also blems.i contemplated moving a click to the right, but there was a breeze from 5 o'clock.

I've been practicing releasing and moving to the next target without watching for an impact if the release feels good (and hence not waiting for an RO call). It's not as easy as it sounds! We'll see if I have the balls to try it on the timed stage next weekend.

[StoneHendge]

Fail me once, shame on you. Fail me twice shame on me.

Easiest stage of the match on Saturday. Second stage my squad shot, with 5 targets from 205 to 440 - engage near to far off the seat of an old motorcycle from a reverse kneel and then go prone and engage far to near. I get in position and release the bolt and get a misfeed. Pull the charging handle back a bit and ease the round into the chamber. Get on target and just a Click. WTF. Go to yank the charging handle back to cycle in a new round an it won't budge. Take the rifle off the cycle and rest the stock against my thigh for a little leveraged, but it still won't budge. I hear "what's going on?" from the RO. Still nothing. Perhaps not always condoned while on the clock, I crater it three times against my thigh and it finally gives. Only made it through 8 targets in what I had left of the 90 seconds. The last 2 were at 205 and right next to each other and the scope elevation was dialed to them,, so only would have taken a few more seconds. Seriously pissed off to drop 2 on the easiest stage.

Reconstructing events, the bipod was down and the way I set up the position, my support bag was clearly pushing pretty hard on the 20 round Duramag. A misfeed had happened to me once before on the clock when the mag got pushed back, and it's also happened at least once in a practice session. So 2 misfeeds in 5 matches (25 stages) and at least 3 in about 700 rounds. OK, the mag is tilting and causing the misfeed, but it's never happened with any other rifles - including those same mags with Gigi in more matches and about 4k rounds as a 243 LBC.

So I go to measure to see how much the mag lip moves from normal to a full pressure tilt and it's about the same in Rubin and GiGi. And then I do another measurement to find that the barrel extension sits in Rubin's upper receiver 0.025" higher than it does in GiGi. (Rubin is a billet 2A Armament matched set while GiGi is an an old Aero matched set with a monolithic upper). In addition, the BCG channel Rubin's upper is extremely tight - with noticable increased wear on the JP carrier after only a few hundred rounds in it. So I'm guessing with the mag tilted, the round catches on the higher barrel extension and the carrier has extremely limited play to work it's way through the catch and jamola. Tight tolerances are great, but they can be too tight

I dont know why the round didn't fire or why I had to crater it. Probably due to the round getting roughed up. It doesn't matter. It can't happen again. Rubin has been disassembled and GiGi is wearing the 16" Lilja nicely! With 4k on the 243 LBC, it'll go on Rubin for practice duty until it's shot out. It makes more sense to use the lighter rifle for practice anyways. A super light rifle is great and a fun challenge, but it's shortcomings certainly do manifest themselves on speed stages and more precarious props.

Ultimately, I'll probably put a 223 barrel in Rubin. Maybe a 16" light contour JP can be found in the future. Or the Lilja M4 barrel they designed for the Navy Seals. I can't see 223 having the same issue given how much thinner and sleeker the cartridge is. I'm guessing the receiver set is probably even optimized for 223 - I don't think the world that 2A thinks about goes outside of it.

And yes, the bruise on my right thigh has an interesting kaleidoscope of colors.....

[r.tenorio671]

...enjoyed reading that whole thread, some good technical info was gleaned from the history of the changes you made along the journey.

[StoneHendge]

Rubin is GiGi and GiGi is Rubin. The patriot brown barrel doesn't look nearly as bad with black as I thought it would.

   

[StoneHendge]

I'm pretty confident this is likely what happened:

   

The misfeed dented the brass and caused the body/shoulder junction to push out slightly. The shoulder couldn't get flush into the chamber so it wasn't seated in all the way, hence the need to crater. If there is a next time (hopefully there isn't), toss the round that gets jammed up!