Thread: .22TCM Micro Varmint rifle build

I realize you might be busy, and have only just posted more info for us, but for christ sake hurry up with the next edition. I am having fun hitting the like button so many times in one thread.

The Shilen 1-14" is finished and fitted so will run some test loads over the chrony and put it on paper this arvo.
Im still waiting on the Aliant 300MP powder for it, Im really hoping it will even out the horrible extreme spreads that the H110 gives me but retain the good velocity.

I sat down an nutted out the mag situation last night too.
They feed perfect in my Brno Fox .222 but in the .223 they begin to ride up the feed ramp before the feed lips release it up into the controlled feed extractor. This causes misalignment about 50% of the time. I will alter a .223 mag with a plastic block in the rear and shorten the feed lips by about 3mm to match the .222 fox mag, this will let the cartridge pop up earlier and straighter before contacting the feed ramp giving the extractor a better chance of catching it squarely.

I have also just acquired a Brno ZK465 .22 Hornet which may be perfect with the shorter action and the TCM Shilen barrel fitted on it. Ill have to have a close look at the 465s mag though. It may not be wide enough for the .223 sized case.

I will wait for the Alliant 300MP to arrive before I cut the test barrel down inch by inch. Ill shoot 5 rounds at each barrel length taking an average velocity from that. Im not confident the irratic velocity data the H110 will give me will be overly helpful for this experiment.

Brno Fox v 465 = Maccas v Caviar

Go the 465!

With the 465 action, I am sure you will run into problems as they have those internal guide ridges, for want of a better name, and they will be way too narrow for anything based on 222/223 brass, unless you can iron them out and widen it internally. I had a 5.7mm Johnson, 30M1 necked down to 22 cal, and the ribs inside the mag had been flattened out by the fella I bought it off, could only fit four in the mag as well, but that didnt matter much.

Have you thought of using CFEBLK powder, it is sposed to be pretty good for getting speed out of small capacity cases ?? Dunno where you could get it over there, here it is distributed by Winchester Australia.

Good luck with the project.

Awesome thread....where's the next installment ?

Ha ha.. calm down you lot Its nice to see some interest in my thread but unfortunately this one is happening in real time..
Im running a 7 day a week business as well as a household with 2 kids, one is only 3 months so free time is a comodity at the moment and I oftern find myself in the worksop after midnight just to get time to myself..

I prefer to post solid info and progress which also serves a double purpose for me, it not only documents the build and testing but helps me double check everything so I dont make silly mistakes but also gives you lot a chance to share your ideas and opinions which I am greatfull for.

I have chronoed the new shilen barrel and Im very happy with the results but Im waiting for the Aliant 300MP powder to arrive befor I do any real accuracy testing with it.
I will make a start on a mag to feed the TCM in the intermission while we wait on courier companies etc.

Here a look at my shiney new 1-14" Shilen tube instead. Sorry about the crappy low light indoor pics

Fantastic write up, photos and story. Following with interest as 22TCM is something ive been intrigued by as well for exactly the same reasons.

Ive played around with numbers in QL before, which is of academic use only, but plugging your data in gives some info that could be useful for what velocities you might expect from a shorter barrel

Thank you for that.. Ill update my current load dimentions later for a more accurate graph. My COAL is quite long compared to oem specs with room to grow if I push the throat forward a little more. My current load with the std freebore reamer seat a flat base Blitzking inline with the bottom of the neck to shoulder junction and that gives me 10 thou jump to lands.
Out of interest, what does Quickload suggest is the optimal barrel length to get max velocity from this load?

Primers are also something I need to test. The factory ammo uses a small pistol primer but Ive been testing with small rifle Federal gold match primers. I will load some pre fire formed brass with various powders and primers when I get to accuracy testing and load development stages .

Fair go there Wingman, we are only trying to give you a little more encouragement, you are doing a bloody good job, the like button got hit again, but please, please, lay off with the lame excuses and get back into the workshop.

I like everything but the bolt handle lol

Cz 527 and brno fox bolt handles are a PITA.. no clearance on scopes unless you use very high rings.. I cut this one off and reshaped it to work with low mounts.. this particular action is not actually staying as the TCM, it has a take down alloy an carbon fiber chassis which this bolt handle is more fitting.

I started with a COAL of 38 - 40mm looking at your photo, but QL gave pressures and velocities that seemed a bit low - COAL makes a huge difference in QL and also QL can't account for individual variances. So i fudged the COAL to match your velocity results, which should give corresponding proportional numbers for barrel lengths. Its all diminishing returns past 20" - about 23fps per inch. 18" looks to be a good balance between maximizing velocity vs handiness.

also FYI QL suggests (to be taken as advice only , its just a software calculation as you know ) that youd be around 49k PSI with 13gr to make that velocity from that barrel , and 13.4 grains will have you hitting up to 55k PSI. H110/W296 seems to be about the best powder choice for it.


Once youve made your final barrel would you be interested in selling on the reamer?

My COAL is 39mm running 13gr of H110 with an average speed of 3180fps in the 22" 1-12" twist but the ES is all over the show. It might get better on the second loading once all the brass is fire formed.

I machined the 1-14" twist Shilen to 20" and the 2 test shots gave me 3210 and 3203fps with the same load over the chrony.

I have high hopes for the Aliant 300MP after reading the great results of .22K Hornet shooters on forums in regards to velocities and single figure extreme spread numbers.

Its looking like cutting up and velocity testing my other barrel will be a waist of time and ammo. The 20" Shilen points real nice and hasnt lost any speed over the faster twist 22" barrel.
The 22" 1-12" might be better for another test I have in mind.. .22TCM 40deg improved..
I can ream the TCM chamber with a .223AI reamer to give it a 40deg neck and straighter walls. Could be better for 50-55gr bullets or another 150-200fps from a 40gr bullet.



Im not certain the reamer will still be any good after it gets through the cues of guys barrels that are waiting patiently in line for this chambering.

A little more midnight oil burnt and I got the Shilen barrel threaded for a suppressor and loaded some more test loads.
This time I loaded on once fired brass and use CCI BR-4 primers to see if there was any change in the extreme spreads. I also backed off the H110 charge from 13gr at 3180fps to 12.5gr at 3050fps which matched the Lilgun pressures and velocities a bit better.

I loaded both 12.5gr of H110 and 10gr of LilGun with 40gr Sierra Blitzkings and put them on paper at 100y.

I still have the 7x VX1 mounted as my picatinny rail adaptor still hasnt arrived from USA to fit some bigger glass. There was also a bit of wind from right to left which resulted in some slight horozontal stringing but still some respectfull groups.

The extreme spreads were better but still nothing to write home about...

H110 : 3015 3030 3051 3042 3059



LilGun : 3034 3069 3028 3081 3042



My Alliant 300MP arrived today and also some Hornady 40gr BT V-Max projectiles so Ill try and make time tomorrow to test that too.

The suppressor made for much quieter shooting, about the same report as a .22 magnum.
I also made up a blind fit thread protector to keep it looking tidy.

I like the idea of a blind thread cap.
I made a little muzzle brake for my 10/22 to cover the thread when the silencer wasn't fitted but the blind cap is simply elegant.
Nice