The Unofficially Official Sub-Caliber/“Micro Bore” thread!

I'm currently working on two .10 Eichelberger Long Rifle builds. One barrel is a .10 caliber 16" long barrel blank (will have to be an SBR or pistol) and the other is a completely finished and ready to shoot barrel for a TC Contender. I had a custom die set made for necking down the .22LR primed brass. It's a pain in the ass, it's something like 12 steps and then bullet seating. The bullets are 7.2 grain solid copper that were each made one at a time on a Swiss Mill. Here's 2 photos with a .10ELR I made/loaded next to a factory .22LR. The photos don't really convey how stupidly small the .10ELR caliber actually is:

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These are the muzzle ends of the .10ELR TC Contender barrel (left) and a Mk15 Mod 1 .50BMG barrel (right):

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It might be funny to caption the barrel photo with "Finding herself" on the left and "Ready to settle down" on the right :ROFLMAO:
 
.22 Pokey

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Don't have any of these, just like the photos. :)
Man, those are cool.

I can’t believe I missed this thread! It was born when I was recovering from eye surgery, I guess.

I love the small calibers. For PDogs I shoot multiple .204, 17 Hornet, and subsonic 22LR for the up close and personal. All suppressed.

I own a CZ 22 Hornet in their euro Lux stock that is just so sweet.

I bought a used CZ 221 FB with beautifully figured wood. Had the thought I was going to enjoy the easier mag loading and bolt cycling vs. 17 Hornet, but I couldn’t find any extra mags!!!

Bought some CZ .222 mags as some said they’d work but I couldn’t get that to work well. Didn’t want to invest a ton of time modding the .222 mags, didn’t even know if it was possible, and sold it.

Pics I have on hand
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Original Tikka T3 .204 (needs threading, haven’t shot it)

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CZ 527 .204, has different scope now

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Rem .204 in KRG W3 chassis and MKM experimental grips & magwell. Gotta trim those bolts that attach that Arca plate on the front. Bugs me.
 
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Wow, pleased to see some honest interest here!

Since I made this post, I’ve done almost nothing with any of my rifles. A few days after starting this thread, we found out I had significant blockages in one of my coronary arteries, so I had two stents placed mid-April. Then I got rear-ended in May, had gallbladder problems in July, and finally got that out late August, followed by a nasty reaction to a pain med for that, and finally an infected incision. It’s been one helluva shitty year…

I did recently accept a position to manage the local airport, so that’s kind of cool. Bit of a wild story, but it’s been HORRIBLY mismanaged since December of last year. I essentially got promoted from Asst. Manager to Manager on my first day (long story), and it’s a literal disaster here on so many levels, but I’m working very hard to get things fixed and running correctly.

One of my issues though is a coyote infestation. We see several a week that go where they want, when they want. They’re not scared of anything, and on an airport that’s a bit of a problem. We’re a bit rural here, so I touched base with the Airport Board Director and we’re going to verify the legalities of me taking them on the field. If I get the green light, the .17s may get the nod initially. I’ll see how they perform, and if they do OK I’ll use them as long as I can (until the yotes learn to stay farther away) to take advantage of the drastically reduced chance of a ricochet that the little .17s offer. Once they learn, I guess the .223 will have to come out.

Anyway, I’m slowly getting back in to things, and have stocked up on some IMR 4198 that came up locally at a good price. That should keep me shooting for quite some time. More to come as I get the ball rolling, but please keep sharing! I love seeing the oddball little cartridges like those above!
 
Here's my 20-250 Impulse Predator after chopping 6 inches off the barrel.
Was shooting 55's at 4,200 with H4350.
Haven't chrono'd it after the chop, but it still shoots micro groups and is a lot easier to maneuver with now.
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I don't know how I missed this thread when it originated. I'm a big fan of the small calibers for shooting pdogs and even coyotes. My favorite is the 204 Ruger (have a couple of them) but I have 17 Rem, 20 VT, and 20 Practical also.
 
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Here's my 20-250 Impulse Predator after chopping 6 inches off the barrel.
Was shooting 55's at 4,200 with H4350.
Haven't chrono'd it after the chop, but it still shoots micro groups and is a lot easier to maneuver with now.
View attachment 8243033
I am running 55's in my 20-250 chopped barrel to 18" getting 3450 fps running H4350.

4200 fps is impressive. How are you seating your bullets?

What primer you using?