Ultralight Ultralight Rifles

[KyleR1985]

I’ve had a 2-64 hex screw and red loctite in my BCA for a few hundred rounds now. No signs of leakage or movement. My assumption is the remainder of the port is filled with copper at this point.

I tapped it, but on another barrel I just screwed the screw in without threading and it bit really good.

I’m an idiot don’t listen to me.

Wear eye protection when you shoot.

To me a 2-64 cap screw, with a heat fit sleeve with a slot for the cap of the screw seems like the best answer. lock the screw down, tight seal with loctite. Then the sleeve to keep the screw located.

Or, buy portless.


I’m not changing anything about my BCA though, until it stops shooting sub MOA groups at 100 with a freakin 5x micro prism scope.

 

[Hoosker Doo]

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

I went ahead and windowed some ASC mags. At 2.37" the bullet tips of the 90 ELD-X touch the front of the mag well, but mags load just fine.

I loaded up 10 rounds with my hottest load of 25 gr H335 now with a COAL of 2.37 instead of sub 2.3" like it was with my first go round.

The good:
● My velocity average went up 90 fps.
Before 25 grains gave me 2515, and today I got 2604 fps.
● No more sticky bolt. Rounds fed and ejected very smoothly.

The bad:
● My group opened up. 10 rd group is roughly 3" across.
● I was punching primers on 6 of the 10 shots. Nothing to crazy. Just enough to let a little smoke seep out of the action. The ones that didn't punch through the primers are pretty heavily cratered.

So...

I'm going to make sure 2.37" doesn't have me jammed into the lands causing pressure spikes. If that's not the case, I will drop the powder charge down .4 or .5 grains and see if I can find an MOA accurate, non-pressurized load that will get me at leat 2550 fps.

Primers are CCI 400
My lower velocities were on some of the blown primers, so that average might have been higher without that malfunction

 

[doverpack12]

For those using the PA 5x microprism. Mil or 5.56/308 reticle?

Using with ULUL Shaw portless 16”.
AAC 77 TMK at 2565
Hand load 77 TMK 2750

Also any way to get the reticle subtensions on the 5.56/308

And the mil chevron subtensions

 

[ezwy]

For those using the PA 5x microprism. Mil or 5.56/308 reticle?

Using with ULUL Shaw portless 16”.
AAC 77 TMK at 2565
Hand load 77 TMK 2750

Also any way to get the reticle subtensions on the 5.56/308

And the mil chevron subtensions

I have the 5.56 .308 reticle. I like it. Don’t know the subtensions but I’m sure it’s out there somewhere. It has scale built in to the reticle for quick ranging/wind and such.
I can hit my 12” steel out to 400 with 55 grain v max or 73 eldm factory loads. Past 400 I think they start to spread a lot.

 

[gtriple]

For those using the PA 5x microprism. Mil or 5.56/308 reticle?

Using with ULUL Shaw portless 16”.
AAC 77 TMK at 2565
Hand load 77 TMK 2750

Also any way to get the reticle subtensions on the 5.56/308

And the mil chevron subtensions

Absolutely go with the MIL. I’ve got both and the MIL is much better for drops

 

[doverpack12]

What would everyone make of this?
I switched my 22 ARC from gas to straight pull this morning. Was hand feeding some ammo and noticed this smudge spot on bullets as I was extracting.
This is 88 ELDM factory ammo, it’s shot ok not fantastic. Almost looks like it’s contacting to me. I dropped these in by hand and closed the bolt on them.



Factory 75 grain ELDM

It’s there but not nearly as bad. I made sure to hold these in while extracting. They did not drag or touch anything on the way out

 

[Thegman]

What would everyone make of this?
I switched my 22 ARC from gas to straight pull this morning. Was hand feeding some ammo and noticed this smudge spot on bullets as I was extracting.
This is 88 ELDM factory ammo, it’s shot ok not fantastic. Almost looks like it’s contacting to me. I dropped these in by hand and closed the bolt on them.

View attachment 902201

Factory 75 grain ELDM

It’s there but not nearly as bad. I made sure to hold these in while extracting. They did not drag or touch anything on the way out

View attachment 902202

We're these dropped into the chamber and you let the bolt carrier drop on them? If so, about all it could be is bullet contact in the chamber throat. Why it wouldn't be all the way around the bullet is a little strange. Almost like something raised in that part of the chamber?

On the upper pictures it looks like there might be minor scratches from the barrel extension lug cuts, but can't see those accounting for smears.

 

[doverpack12]

We're these dropped into the chamber and you let the bolt carrier drop on them? If so, about all it could be is bullet contact in the chamber throat. Why it wouldn't be all the way around the bullet is a little strange. Almost like something raised in that part of the chamber?

On the upper pictures it looks like there might be minor scratches from the barrel extension lug cuts, but can't see those accounting for smears.

I dropped them in the chamber one at a time. No feed ramp contact at all. Then closed the bolt on them.

I’m thinking the uneven contact could be why the barrel doesn’t really want to shoot. Barrel and bolt are same manufacturer.

 

[C Bow]

If you take a black marker and color the whole bullet then run some thru like that you can see everywhere they touch also that could be the extractor pressure as loaded cartrage comes out

 

[KyleR1985]

For your analysis: I recently had a 5.56 BCA 16 inch pencil barrel cut down to 8 inches for my SBR. The barrel weighed 16.5oz before the cut and thread, and 10.7oz after. So that should give you a ballpark for how many ounces you'd lose going to a 10.5 inch barrel.

The 77tmk ammo I use does about 2750fps in a 16 inch barrel, and about 2230fps in the 8 inch barrel. That is enough velocity for the bullet velocity to stay above 1800fps to about 280 yards at my elevation. So, an 8 inch barrel would work well for a 200 yard gun. You will likely gain a couple hundred fps going from 8 to 10.5 if the extra velocity is needed.

You may have answered elsewhere - how does this 8" barrel shoot? 2moa or better?

 

[packgoatguy]

You may have answered elsewhere - how does this 8" barrel shoot? 2moa or better?

Meh... it shot ok with my customized fostech magnesium upper, but not great with the solo300 upper. I tried one of the bca factory 10.5 inch ones and it shoots better.

 

[Hoosker Doo]

I went ahead and windowed some ASC mags. At 3.37" the bullet tips of the 90 ELD-X touch the front of the mag well, but mags load just fine.

I loaded up 10 rounds with my hottest load of 25 gr H335 now with a COAL of 3.37 instead of sub 3.3" like it was with my first go round.

The good:
● My velocity average went up 90 fps.
Before 25 grains gave me 2515, and today I got 2604 fps.
● No more sticky bolt. Rounds fed and ejected very smoothly.

The bad:
● My group opened up. 10 rd group is roughly 3" across.
● I was punching primers on 6 of the 10 shots. Nothing to crazy. Just enough to let a little smoke seep out of the action. The ones that didn't punch through the primers are pretty heavily cratered.

So...

I'm going to make sure 3.37" doesn't have me jammed into the lands causing pressure spikes. If that's not the case, I will drop the powder charge down .4 or .5 grains and see if I can find an MOA accurate, non-pressurized load that will get me at leat 2550 fps.

Primers are CCI 400
My lower velocities were on some of the blown primers, so that average might have been higher without that malfunction
View attachment 902102View attachment 902103View attachment 902104View attachment 902105View attachment 902107

6x45 Solo, 16" X-caliber update:

Keeping length at 2.37", I dropped my powder (H335) charge to 24.0 gr. My group tightened back up, but I still punched 2 out of 5 primers.

I decided to keep the load and switch fromm CCI 400 to Winchester #41 .556 primers.

10 shot Result:

I did have one failure to fire - I blame a bad primer, not the polymer lower parts kit. There was a normal looking strike on the primer. Handling the round afterwards kinfmd of felt like holding a grenade with the pin pulled, and I gave it some distance haha. So 10 shots turned into 9.

Primer strikes looked normal.

Group stayed tight (<1.5") circled shot was a pull. I called it at the shot before checking the target.

Speed slowed about 10 fps with the new primers, but I'm still above 2500 fps which puts me at 1800 fps out past 400 yards.

 

[KyleR1985]

6x45 Solo, 16" X-caliber update:

Keeping length at 3.37, I dropped my powder (H335) charge to 24.0 gr. My group tightened back up, but I still punched 2 out of 5 primers.

I decided to keep the load and switch fromm CCI 400 to Winchester #41 .556 primers.

10 shot Result:

I did have one failure to fire - I blame a bad primer, not the polymer lower parts kit. There was a normal looking strike on the primer. Handling the round afterwards kinfmd of felt like holding a grenade with the pin pulled, and I gave it some distance haha. So 10 shots turned into 9.

Primer strikes looked normal.

Group stayed tight (<1.5") circled shot was a pull. I called it at the shot before checking the target.View attachment 906386

Speed slowed about 10 fps with the new primers, but I'm still above 2500 fps which puts me at 1800 fps out past 400 yards.

View attachment 906396

3.37 = 2.37(typo)?

Or 2.337” (typo)?

Otherwise please provide your lower receiver maker, I need that extra OAL!

 

[Hoosker Doo]

3.37 = 2.37(typo)?

Or 2.337” (typo)?

Otherwise please provide your lower receiver maker, I need that extra OAL!

Hahaha yeah, typo. Edited

Thanks

2.370"

 

[ezwy]

I’m wondering about NFA polymer lower parts kit durability. I’ve had some light primer strikes and misfires and I just noticed today that the hammer has some deforming from hitting the firing pin. This might not be the only issue with this one though.
Of the four Solo uppers I have been exposed to, this one doesn’t like to stay in battery as well. The detent bearing gets stuck periodically and won’t engage (bolt has to be taken out and bearing popped back into its socket).
A good portion of the misfires were likely due to being barely out of battery.
All that said, I really like this setup and this is after 500+ rounds.

 

[Taudisio]

6x45 Solo, 16" X-caliber update:

Keeping length at 2.37", I dropped my powder (H335) charge to 24.0 gr. My group tightened back up, but I still punched 2 out of 5 primers.

I decided to keep the load and switch fromm CCI 400 to Winchester #41 .556 primers.

10 shot Result:

I did have one failure to fire - I blame a bad primer, not the polymer lower parts kit. There was a normal looking strike on the primer. Handling the round afterwards kinfmd of felt like holding a grenade with the pin pulled, and I gave it some distance haha. So 10 shots turned into 9.

Primer strikes looked normal.

Group stayed tight (<1.5") circled shot was a pull. I called it at the shot before checking the target.View attachment 906386

Speed slowed about 10 fps with the new primers, but I'm still above 2500 fps which puts me at 1800 fps out past 400 yards.

View attachment 906396

I punched your numbers against a little lighter load than mine now. The 90gr eldx has a posted g1 of .409 vs the .400 of the 87gr vmax. Your average at 2505 and I ran it against 2650 for the vmax, my load average is 2688 but on the hot side when it’s warm.

I didn’t change any other variable except velocity and bc’s.

 

[Taudisio]

I’m wondering about NFA polymer lower parts kit durability. I’ve had some light primer strikes and misfires and I just noticed today that the hammer has some deforming from hitting the firing pin. This might not be the only issue with this one though.
Of the four Solo uppers I have been exposed to, this one doesn’t like to stay in battery as well. The detent bearing gets stuck periodically and won’t engage (bolt has to be taken out and bearing popped back into its socket).
A good portion of the misfires were likely due to being barely out of battery.
All that said, I really like this setup and this is after 500+ rounds.

View attachment 906615

I saw this starting with mine as well. Made me have some slight doubts and decided I’d rather not take any chances (however slim they may have been) and swapped it for a cartridge trigger.

 

[Taudisio]

Over here in my world, I have a complete rifle waiting for the Shaw portless except an optic, and a lower ready for an UL gassed 22ARC!
Farrowtech changed their stock pad. It does not have any hexagon holes, and it’s thicker. The screw they sent with it does not go all the way through the polymer. I’m guessing it is heavier as well but we are in the process of moving and I haven’t weighed it.

 

[KyleR1985]

View attachment 906680
Over here in my world, I have a complete rifle waiting for the Shaw portless except an optic, and a lower ready for an UL gassed 22ARC!
Farrowtech changed their stock pad. It does not have any hexagon holes, and it’s thicker. The screw they sent with it does not go all the way through the polymer. I’m guessing it is heavier as well but we are in the process of moving and I haven’t weighed it. View attachment 906682View attachment 906683

Tell me about that buffer?

I have an sbr 12.5” 6ARC gasser that I need to tame. Even with the SA bleeding off as much gas as possible it’s still over gassed. May need a new buffer

 

[Taudisio]

Tell me about that buffer?

I have an sbr 12.5” 6ARC gasser that I need to tame. Even with the SA bleeding off as much gas as possible it’s still over gassed. May need a new buffer

It is a JP silent capture. I cannot stand the “twang” from a normal ar bolt being closed. I don’t think it’s any lighter, but it’s as necessary as a suppressor.