Ultralight Ultralight Rifles

[groc426]

What I now do on all my 223 AR ramps is break the sharp edge on the lug cuts where the bullet is hanging up.

The simplest method I've found is to put the barrel in a paddled vice, wrap a small piece of 400 grit wet-dry sandpaper around the tip of the bullet in the cartridge and -gently- push the bullet through the ramp in its normal feeding orientation, straight into the lug cutouts, -only- making contact at the sticking point, not the ramp itself. I check frequently with the bare bullet to see how much the sticking has been reduced.

Once the bullet is moving through with little or no sticking, I finish with 1,000 grit. I'm not aggressive with it and it takes very little removal. You're really -just- breaking the sharp edges on the barrel extension ramps, where the bolt lugs pass, that are cutting into the bullet.

I stole this from the internet, but is this the part of the lug cuts that you're smoothing out:

My apology for simple questions. I have never owned an AR, let a lone built one. I've read through all the pages of this thread and took notes. I ordered the recommended parts and just waiting for their arrival.

I have chased affordable, lightweight rifles for years and have always fallen short. I'm super excited about building an ULUL rifle. Thanks everyone for sharing such great information!

 

[Taudisio]

I stole this from the internet, but is this the part of the lug cuts that you're smoothing out:

My apology for simple questions. I have never owned an AR, let a lone built one. I've read through all the pages of this thread and took notes. I ordered the recommended parts and just waiting for their arrival.

I have chased affordable, lightweight rifles for years and have always fallen short. I'm super excited about building an ULUL rifle. Thanks everyone for sharing such great information!

If you run into issues or hiccups, post them here. You probably aren’t the only one to have it, and there are a lot of knowledgeable folks here that help out!

 

[Hoosker Doo]

So I ordered a Solo 300 and a barrel from X-caliber in 6x45 to go on it. I started sizing brass and loaded a few rounds up to try as soon as the barrel got in. Upon mounting the barrel, my loads/resized brass would only chamber if I slammed the action shut and there were small nicks on the rim of the casing. If I trimmed my brass down from 1.75" to 1.73 pr lower, it would chamber smoothly.

So I sent the barrel back to X-caliber with my solo bolt and a sized brass and dummy round so they could check for burs and correct depth of chamber. They said they found the chamber to be to spec and "your included bolt failed to close into battery on our PT&G Go Gauge for that cartridge, which means it would already be exacerbating your issue."

So I think I will get an X-caliber bolt (they have a 1 MOA guarantee with their bolts head spaced to their barrels). But that $100 I didn't plan on spending. I haven't contacted Solo yet. I may just let them know, but not sure if I want a replacement or anything.

Thoughts?

So a couple months later, I finally got my RCA bolt shipped back with my barrel and properly headspaced to my X-caliber barrel. I loaded up a ladder of different charges of H335 and .556 brass I resized to 6x45 - untrimmed, and what do you know? All of them chambered very smoothly.

I never did contact Elijah, but it seems that Solo bolt was the issue. I'll shoot tomorrow and see how everything cycles and chambers, but as of now it's day and night difference and I'm excited about my ULUL again

 

[Taudisio]

So a couple months later, I finally got my RCA bolt shipped back with my barrel and properly headspaced to my X-caliber barrel. I loaded up a ladder of different charges of H335 and .556 brass I resized to 6x45 - untrimmed, and what do you know? All of them chambered very smoothly.

I never did contact Elijah, but it seems that Solo bolt was the issue. I'll shoot tomorrow and see how everything cycles and chambers, but as of now it's day and night difference and I'm excited about my ULUL again

Just confirming RCA is Rubber City?

I haven’t had to do anything with my solo/xcaliber combo with new LC brass except run a neck mandrel. Maybe I just got lucky. I’d love to see your results!

 

[Thegman]

I stole this from the internet, but is this the part of the lug cuts that you're smoothing out:

My apology for simple questions. I have never owned an AR, let a lone built one. I've read through all the pages of this thread and took notes. I ordered the recommended parts and just waiting for their arrival.

I have chased affordable, lightweight rifles for years and have always fallen short. I'm super excited about building an ULUL rifle. Thanks everyone for sharing such great information!

More or less, yes. The bullet might contact a little deeper in the lugs, but that's the general area (and your extension/bullet combo might not need it, but likely will benefit from it).

In the next issue of G&A AR-15 there will be an article on exactly this, with pics. It's really helpful for most any AR-15 5.56 barrel extension.

 

[Thegman]

A little bit of a sidetrack, but was messing with something that might be helpful:

I -finally- windowed a mag trying to get the longer ELD-M/X to work. Not much success yet, but something else kind of interesting. I ordered some Fusion 75 grain bullets and already had some Speer 75 grain TMJs on hand for load development.

Started thinking: Shortish, heavy bullet. Long bearing surface...large doses of slow powder might work with that, which the shortish bullet and windowed mag at 2.37" COAL allows.

VV N550 so far pushes the bullet over 2,800 fps (actually over 2,900 fps, but that was probably too hot). Several others look like they might pass 2,800 as well. I'm just using some slower powders I have on hand from other bygone projects so it's good to find a use for them.

These bullets also seem to shoot really well. I'll shoot a few things with them over the next 6 months and see how they do.

 

[Taudisio]

A little bit of a sidetrack, but was messing with something that might be helpful:

I -finally- windowed a mag trying to get the longer ELD-M/X to work. Not much success yet, but something else kind of interesting. I ordered some Fusion 75 grain bullets and already had some Speer 75 grain TMJs on hand for load development.

Started thinking: Shortish, heavy bullet. Long bearing surface...large doses of slow powder might work with that, which the shortish bullet and windowed mag at 2.37" COAL allows.

VV N550 so far pushes the bullet over 2,800 fps (actually over 2,900 fps, but that was probably too hot). Several others look like they might pass 2,800 as well. I'm just using some slower powders I have on hand from other bygone projects so it's good to find a use for them.

These bullets also seem to shoot really well. I'll shoot a few things with them over the next 6 months and see how they do.

That is very impressive, assuming your 16” barrel?

 

[Thegman]

That is very impressive, assuming your 16” barrel?

Yes, that's from a BCA 16" pencil barrel (seems to shoot a lot better than one would expect from a $50 barrel!)

 

[ACHILLES]

That’s great velocity. I have the same barrel and it’s shoots my 52SMK Handload at 2980fps with varget 1.2” 5shot groups. It shoots frontier 5.56 55gr fmj’s decent to at 3100fps. Pretty happy with the accuracy for how cheap it was. Haven't loaded the heavies yet but looks like your seeing good velocities.

 

[Hoosker Doo]

Just confirming RCA is Rubber City?

I haven’t had to do anything with my solo/xcaliber combo with new LC brass except run a neck mandrel. Maybe I just got lucky. I’d love to see your results!

Yes, Rubber City.

X-caliber has an MOA guarantee if they pair and headspace a Rubber City bolt with one of their barrels, so now that it will actually chamber, Ii should be able to get a load of some kind to shoot out of this setup. My brother has built a few ULULs and never had an issue with the Solo bolts chambering his reloads or resized brass. I'm just that lucky I guess...

 

[Hoosker Doo]

Well here she is...
View attachment 851920

Thanks to ya'll and some coaching from @ezwy , I've got my build all put together. It's a 6x45, so I've only put a couple rounds down the tube until I get some reloads worked up, but she fired. I'm hoping to get some reloads worked up and get it broke in and running smooth in the next couple weeks.

● Xcaliber barrel
● Amazon carbon tube handguard with pre-threeaded barrel nut
● Solo upper
● TN lower with polymer lower parts kit and trigger
● Hogue 15° grip
● CP Firearms buttstock with peel n stick neoprene pad
● 4-12x40 Leupold scope

Total weight - 4 lb 6 oz with 10 rd duramag

I'm pretty stoked with how it turned out and the final weight. A couple pleasant surprises were how consistent and light the 2 stage polymer trigger pull ended up being. I was planning on upgrading, but won't now unless I have a reason too. Also the 1/2" peel n stick neoprene bonded right to the buttstock and is a perfect cushion/recoil pad.

View attachment 851924

I did add some anti walk trigger pins because I was constantly pushing then back in without even firing any rounds.

Thanks for the ideas and guidance in this thread.

I inserted the quote with my original post of my 6x45 ULUL build. Now with a Rubber City Bolt head spaced by X-caliber, everything chambers nicely.

I worked up a ladder of loads with 90 gr ELD-X and H335, staring with 23.5 gr and going 24.0, 24.5, and 25.0 gr with 5 shots per group.

All loads shot and extracted well until I started to hit some pressure with my last string.

With 16" X-caliber, my velocities were:

23.5 gr- ~2400 fps
24.0 gr- ~ 2430 fps
24.5 gr- 2504 fps
25.0 gr- 2515 fps

I could have probably tried a little harder/set up a little better for precision/accuracy, but here were the groups shot of a bench using a spartan bipod and a rice bag under my rear hand. The orange dot is 1/2". Distance between white lines is 1".

23.5 gr - one of the shots in the cluster of 3 hit a leaf or branch the wind blew into my line of fire and made a shrapnel pattern on the target.


24.0 gr


24.5 gr (Not sure on the first one touching the bull)

25.0 gr - Some of these were a little sticky to extract. Nothing crazy, but I will probably go down a couple tenths of a grain to see if I can keep the velocity but get rid of the sticky bolt because I liked this group the best.

It was pretty sweet to shoot, and per the Hornady app, that will get me out past 400 yards before dropping below 1800 fps. I'm excited to get this dialed in a little more and start shooting a lot.

Edit to add bullet info

 

[KyleR1985]

I inserted the quote with my original post of my 6x45 ULUL build. Now with a Rubber City Bolt head spaced by X-caliber, everything chambers nicely.

I worked up a ladder of loads with 90 gr ELD-X and H335, staring with 23.5 gr and going 24.0, 24.5, and 25.0 gr with 5 shots per group.

All loads shot and extracted well until I started to hit some pressure with my last string.

With 16" X-caliber, my velocities were:

23.5 gr- ~2400 fps
24.0 gr- ~ 2430 fps
24.5 gr- 2504 fps
25.0 gr- 2515 fps

I could have probably tried a little harder/set up a little better for precision/accuracy, but here were the groups shot of a bench using a spartan bipod and a rice bag under my rear hand. The orange dot is 1/2". Distance between white lines is 1".

23.5 gr - one of the shots in the cluster of 3 hit a leaf or branch the wind blew into my line of fire and made a shrapnel pattern on the target.
View attachment 897488

24.0 gr
View attachment 897489

24.5 gr (Not sure on the first one touching the bull)View attachment 897490

25.0 gr - Some of these were a little sticky to extract. Nothing crazy, but I will probably go down a couple tenths of a grain to see if I can keep the velocity but get rid of the sticky bolt because I liked this group the best. View attachment 897491

It was pretty sweet to shoot, and per the Hornady app, that will get me out past 400 yards before dropping below 1800 fps. I'm excited to get this dialed in a little more and start shooting a lot.

Edit to add bullet info

What’s your OAL on those?

 

[Hoosker Doo]

What’s your OAL on those?

Mag length on an unmodified duramag. I need to borrow my calipers back from my brother to get the true OAL

 

[SteveAndTheCrigBoys]

First ULULOG? lol. 36 3/4" OAL, 28 1/2" with the stock folded

Love the balance compared to the other muzzle-forward cans I've had on here. Oughta run the 20 shot drill with it to see if I score better on my off hand and seated unsupported shots.

 

[Taudisio]

First ULULOG? lol. 36 3/4" OAL, 28 1/2" with the stock folded

Love the balance compared to the other muzzle-forward cans I've had on here. Oughta run the 20 shot drill with it to see if I score better on my off hand and seated unsupported shots.

View attachment 897540

I’m lost on the OG?
Which trigger is that?

 

[Taudisio]

I inserted the quote with my original post of my 6x45 ULUL build. Now with a Rubber City Bolt head spaced by X-caliber, everything chambers nicely.

I worked up a ladder of loads with 90 gr ELD-X and H335, staring with 23.5 gr and going 24.0, 24.5, and 25.0 gr with 5 shots per group.

All loads shot and extracted well until I started to hit some pressure with my last string.

With 16" X-caliber, my velocities were:

23.5 gr- ~2400 fps
24.0 gr- ~ 2430 fps
24.5 gr- 2504 fps
25.0 gr- 2515 fps

I could have probably tried a little harder/set up a little better for precision/accuracy, but here were the groups shot of a bench using a spartan bipod and a rice bag under my rear hand. The orange dot is 1/2". Distance between white lines is 1".

23.5 gr - one of the shots in the cluster of 3 hit a leaf or branch the wind blew into my line of fire and made a shrapnel pattern on the target.
View attachment 897488

24.0 gr
View attachment 897489

24.5 gr (Not sure on the first one touching the bull)View attachment 897490

25.0 gr - Some of these were a little sticky to extract. Nothing crazy, but I will probably go down a couple tenths of a grain to see if I can keep the velocity but get rid of the sticky bolt because I liked this group the best. View attachment 897491

It was pretty sweet to shoot, and per the Hornady app, that will get me out past 400 yards before dropping below 1800 fps. I'm excited to get this dialed in a little more and start shooting a lot.

Edit to add bullet info

If you window your mag, and extend your COAL, you should be able to ease the pressure back at the higher loads. I run my stuff on the hotter end, but I was able to get up to 25.4gr of h335 in with the 95gr TMK and don’t remember any noticeable pressure signs. It broke 2600fps at 25.1gr and 2664 at 25.4. But that was also a cold, end of November, morning, so make sure you’re going slower during the summer heat.

I have some 90gr eldx’s on my shelf. I should load up a pressure test with my barrel….

 

[Thegman]

I inserted the quote with my original post of my 6x45 ULUL build. Now with a Rubber City Bolt head spaced by X-caliber, everything chambers nicely.

I worked up a ladder of loads with 90 gr ELD-X and H335, staring with 23.5 gr and going 24.0, 24.5, and 25.0 gr with 5 shots per group.

All loads shot and extracted well until I started to hit some pressure with my last string.

With 16" X-caliber, my velocities were:

23.5 gr- ~2400 fps
24.0 gr- ~ 2430 fps
24.5 gr- 2504 fps
25.0 gr- 2515 fps

I could have probably tried a little harder/set up a little better for precision/accuracy, but here were the groups shot of a bench using a spartan bipod and a rice bag under my rear hand. The orange dot is 1/2". Distance between white lines is 1".

23.5 gr - one of the shots in the cluster of 3 hit a leaf or branch the wind blew into my line of fire and made a shrapnel pattern on the target.
View attachment 897488

24.0 gr
View attachment 897489

24.5 gr (Not sure on the first one touching the bull)View attachment 897490

25.0 gr - Some of these were a little sticky to extract. Nothing crazy, but I will probably go down a couple tenths of a grain to see if I can keep the velocity but get rid of the sticky bolt because I liked this group the best. View attachment 897491

It was pretty sweet to shoot, and per the Hornady app, that will get me out past 400 yards before dropping below 1800 fps. I'm excited to get this dialed in a little more and start shooting a lot.

Edit to add bullet info

Just got a couple hundred 90 ELD-X in the mail today. That will also be my first stop with the 6x45 when the group buy comes through.

 

[Thegman]

If you window your mag, and extend your COAL, you should be able to ease the pressure back at the higher loads. I run my stuff on the hotter end, but I was able to get up to 25.4gr of h335 in with the 95gr TMK and don’t remember any noticeable pressure signs. It broke 2600fps at 25.1gr and 2664 at 25.4. But that was also a cold, end of November, morning, so make sure you’re going slower during the summer heat.

I have some 90gr eldx’s on my shelf. I should load up a pressure test with my barrel….

That TMK at 2660 with a .5 G1 will be a great 6x45 load

 

[Taudisio]

Just got a couple hundred 90 ELD-X in the mail today. That will also be my first stop with the 6x45 when the group buy comes through.

I suppose I have a free weekend to go load up a few rounds and pressure test them. Any preferred powders you want me to try that I may have on hand?

 

[Thegman]

I suppose I have a free weekend to go load up a few rounds and pressure test them. Any preferred powders you want me to try that I may have on hand?

Yeah! AA 2200, 2230, 2460, 2520, SW Tactical, AR Plus, Match Rifle, Benchmark, 3031, Alliant Varmint, AR Comp, RL 10X, X-Teminator, Tac...

I suppose you'll try 335, but that's one I've actually never had nor used but will probably need to try with the 6x45.