Ultralight Ultralight Rifles

[Thegman]

Check you KVP PCC handguards!

I was working on some things earlier today and hand installed a 5.56 barrel in a CMT upper (a well made upper). I just used a KVP handguard I had in the drawer to hold the barrel and hand tightened it.

Once tightened, I noticed the barrel was still loose and had a lot of lateral movement...WTF??

Turns out the last two KVP handguards I've used are too deep from the base of the barrel nut to the interior ledge that interfaces with the barrel extension (0.58"+) and the barrel nut base is bearing on the upper receiver face when tightened.

All the other barrel nuts I had were somewhere between 0.52" and 0.56" for the same measurement and held the barrel properly without touching the receiver face.

Depending on your upper, it may hold the barrel seemingly well, but if it contacts the receiver face there's no way to know your actual torque on the barrel extension. The first KVP handguard I bought in '22 has plenty of clearance, nowhere near the upper. Both of the "bad" ones were from '23.

If you're using one, hold your rifle up to a light and check to see you have clearance.

 

[Taudisio]

Check you KVP PCC handguards!

I was working on some things earlier today and hand installed a 5.56 barrel in a CMT upper (a well made upper). I just used a KVP handguard I had in the drawer to hold the barrel and hand tightened it.

Once tightened, I noticed the barrel was still loose and had a lot of lateral movement...WTF??

Turns out the last two KVP handguards I've used are too deep from the base of the barrel nut to the interior ledge that interfaces with the barrel extension (0.58"+) and the barrel nut base is bearing on the upper receiver face when tightened.

All the other barrel nuts I had were somewhere between 0.52" and 0.56" for the same measurement and held the barrel properly without touching the receiver face.

Depending on your upper, it may hold the barrel seemingly well, but if it contacts the receiver face there's no way to know your actual torque on the barrel extension. The first KVP handguard I bought in '22 has plenty of clearance, nowhere near the upper. Both of the "bad" ones were from '23.

If you're using one, hold your rifle up to a light and check to see you have clearance.

I will go check mine now.

I was not able to find the perfect 300 yard spot in the woods so my groups can not be representative of the loads I tested. I did find a consistent and comfortable spot for 590 yards. I could have stretched it farther, but I was too lazy to move the targets.

 

[Thegman]

Thats probably better than I could do with a 10 pound rifle! That's awesome! Looks to be an all-purpose hunting rifle to me.

I'm currently trying to TMK a grizzly from less than a 1/10 that distance, so I should be good, if ol' Ephraim would only cooperate a little...I think all we have coming is a black bear so far.

 

[Taudisio]

Thats probably better than I could do with a 10 pound rifle! That's awesome! Looks to be an all-purpose hunting rifle to me.

I'm currently trying to TMK a grizzly from less than a 1/10 that distance, so I should be good, if ol' Ephraim would only cooperate a little...I think all we have coming is a black bear so far.

Hopefully you find a grizz! I try to stay out of their territory. An average 275 pound black bear would whoop my azz, I couldn’t even imagine coming face to face with an 800+ pound grizz that literally looks at me the same way I look at a deer. Much less chase one with a 5.56…….

 

[johnnyboots]

Parts are coming today for my build:
Solo 300 upper
Midwest 7" handguard

Later this week the Faxon 7.5" 1/5 barrel gets here. For now, this will live on a Aero lower with an SBA3 and sylvan folder until I nail down the details. Likely going to grab the Primary SLX 3x prism I was hoping would go on sale this week.

Thanks for all the details to @Thegman and others who contributed. This thread is AWESOME

 

[Taudisio]

It was suggested to me to post my results from my bullet testing of the 6x45 for those seeing this in the future. So, I first started off by getting and cutting bullets open to see their construction first hand.

From left to right
90gr Hornady eldx, which is too long for my chamber
87gr Hornady vmax
90gr nosler ballistic tip
80gr nosler ballistic tip
90gr Sierra gamechanger, also too long
85gr Sierra hpbt-“medium game hunting”
85gr speer spbt-also designed for medium game

From the one photo I have seen of the .224-77gr Sierra tmk cross sectioned like so, it appears to be constructed most like the eldx.

 

[Taudisio]

My next step, after starting load development for the 87gr vmax and 90gr ballistic tip, I shot them into gallon water jugs. It’s an easy apples to apples test anyone can get for a few dollars at a grocery store and really push the bullets hard. I have done this with a 77gr tmk in the past and it stopped in the second jug, twice, for reference.
1) 87gr vmax
2) 87gr vmax
3) 90gr ballistic tip

I have the 87gr vmax going 2750 from a 16” barrel. The 90gr ballistic tip has a mv of 2600-longer bearing surface is my strong assumption, I have not measured them to be positive.

 

[Taudisio]

Next I grouped the two against each other at 300 yards. I got a slightly better group with the 87gr vmax, but I was not on a bench and I did not have a rear bag setup so those results need to be tested again. I felt comfortable to shoot them out a bit longer, see the videos I posted earlier. The 87gr vmax that I shot the two liter with, was dug out of the dirt and is below on my tailgate. The bullet in my hand is a 90gr ballistic tip I did the same with, only at 420 yards (first round impact). According to my data and noslers minimum expansion velocity (1800fps), this bullet is only good out to 375ish yards. The vmax is rated for “explosive expansion down to 1600fps” which my data shows it is going 1700fps at 500 yards.

Also photos the weight of my rifle empty and with 10 rounds in the magazine.

I bought a suppressor with intentions of mostly using it on the 6x45. Hopefully with the short wait times, I’ll have it in the next few weeks and decide if it will stay or go, but the rifle should still be under 5 pounds fully loaded and suppressed.

 

[Thegman]

And you were shooting almost 600 yards and doing pretty well with that Primary Arms 5x...with your 3# and change rifle? And still getting apparently good bullet performance.

I don't even know what to say to that.

 

[Taudisio]

And you were shooting almost 600 yards and doing pretty well with that Primary Arms 5x...with your 3# and change rifle? And still getting apparently good bullet performance.

I don't even know what to say to that.

I didn’t mention my quick and dirty shooting position on a front bag only. The farrowtech slides under my bino harness strap and locked solidly into my shoulder while shooting uphill. I’m a big proponent for practicing how I hunt, obviously replace the tailgate for a backpack, tree, or stump.

 

[Thegman]

Looking at the best functioning choices for these straight-pull rifles, 17 Remington, 204 Ruger, 223/5.56, 6x45, 6mm Mongoose*, 6mm Max*, 25-45 Sharps, 277 Wolverine, 300 Blk, 300 HAM’R, 350 Legend (*not really available at this time, and some others I'm missing or leaving out like 450 Socom), I'm thinking the 6x45 might be a contender for the best all-around ultralight-ulralight big game cartridge choice..???

It wasn't a cartridge I'd given a lot of thought to, but Taudisio is pretty convincing with it. I'd like to see some hunting bullet performance results with it, especially at 300+ yards, where some of these other cartridges might start struggling a little. Is bear season still open down there?

 

[Thegman]

I didn’t mention my quick and dirty shooting position on a front bag only. The farrowtech slides under my bino harness strap and locked solidly into my shoulder while shooting uphill. I’m a big proponent for practicing how I hunt, obviously replace the tailgate for a backpack, tree, or stump.

I think there should be an online ultralight-ultralight shooting competition over the summer. Have to figure out some sort of handicap system for lowest shooting weight rifles. It would be like the Special Olympics of rifle shooting...

 

[Taudisio]

Looking at the best functioning choices for these straight-pull rifles, 17 Remington, 204 Ruger, 223/5.56, 6x45, 6mm Mongoose*, 6mm Max*, 25-45 Sharps, 277 Wolverine, 300 Blk, 300 HAM’R, 350 Legend (*not really available at this time, and some others I'm missing or leaving out like 450 Socom), I'm thinking the 6x45 might be a contender for the best all-around ultralight-ulralight big game cartridge choice..???

It wasn't a cartridge I'd given a lot of thought to, but Taudisio is pretty convincing with it. I'd like to see some hunting bullet performance results with it, especially at 300+ yards, where some of these other cartridges might start struggling a little. Is bear season still open down there?

A 20 practical should be in there, though probably just varmint. A subsonic option I have been chewing on is a 338 spectre but it uses 10mm brass and a 6.8spc bolt

Bear is open for those who have a tag until Friday I believe. My tag is sitting at the taxidermist .

 

[johnnyboots]

Saw Peacegeek had these 8.5" .223wydle barrels with no gas port drilling that could be SWEET for a solo build
https://www.peacegeek.net/product-p/z-0381.htm

 

[WyoJeff]

anyone running a 5 round mag? we are talking hunting rifles and saving weight afterall

 

[Thegman]

anyone running a 5 round mag? we are talking hunting rifles and saving weight afterall

The only 5 round mags I've seen have been 10 round mag bodies with extended follower legs to reduce capacity, but admittedly, I've not looked too closely into that question.

 

[JBradley500]

The limiter is pretty much what I have seen too, so it's actually slightly heavier in my case. I have to use one for semi-auto deer hunting.

 

[PsRpOiGrRiAtM]

Looking at the best functioning choices for these straight-pull rifles, 17 Remington, 204 Ruger, 223/5.56, 6x45, 6mm Mongoose*, 6mm Max*, 25-45 Sharps, 277 Wolverine, 300 Blk, 300 HAM’R, 350 Legend (*not really available at this time, and some others I'm missing or leaving out like 450 Socom), I'm thinking the 6x45 might be a contender for the best all-around ultralight-ulralight big game cartridge choice..???

It wasn't a cartridge I'd given a lot of thought to, but Taudisio is pretty convincing with it. I'd like to see some hunting bullet performance results with it, especially at 300+ yards, where some of these other cartridges might start struggling a little. Is bear season still open down there?

It's also got me noodling on a .224 Valkyrie--seems like it would overcome the feeding issues of the short/fat cartridges, but still drives an 88gr ELD-M at decent velocities.

 

[Thegman]

Our little wonder rifles doing what they do! I guess my "big" rifles are in even more danger of gathering more dust.

I'll bet Taudisio's little 6x45 87 V-Max would do even better under the same circumstances...



Full details in the 223 for Pretty Much Everything thread.

 

[Thegman]

It's also got me noodling on a .224 Valkyrie--seems like it would overcome the feeding issues of the short/fat cartridges, but still drives an 88gr ELD-M at decent velocities.

Not sure how well it would extract, but might...???

That said, as shown above, the 223 will likely work just fine for you anyway.