Thread: .22TCM Micro Varmint rifle build

I had a quick session with the TCM today and the new Alliant 300MP powder...
The powder looks just like H110/Win 296 but a quick bit of research found a decoration from Alliant powders saying it is not the same powder and that it is actually slower burning than H110/296.

With that info in mind I put some loads together to work out a max load. I started at 12gr as my H110 load is 13gr and it is meant to be slower than the H110. Here were the 300MP chrony results with 40gr Blitzkings:

12.0gr=2961fps 12.5gr=3060fps 13.0gr=3190 13.5gr=3271 very flat primer.



This is very much the same as my H110 figures and I was expecting to be able to get 14gr to 15gr in before seeing the pressure signs I saw at 13.5gr. The powder was not compressed and there is room for about 15gr without a crunch but it seems its not as slow as I was hoping so I called 12.8gr my max load.

Something I did notice was how much cleaner it burned and the lack of any sooty deposits on the necks unlike the H110 and Lilgun which are on the left and middle of this pic with 300mp on the right..




So I loaded 5 rounds of 40gr Sierra Blitzkings and 5 rounds of 40gr Hornady V-Max to put over the chrony on paper.
The V-Max's were a dream to load, the small boat tail helped them seat smoothly and perfectly (and concentric without having to try) without all the nursing it takes with the flat base Blitzkings.



The V-Max's had to be seated a bit deeper to clear the lands as the ogive shape is quite a bit different to the Blitzkings.
This made for higher pressures and velocities than the Blitzkings so I will have to load those ones down a touch to preserve my pimer pockets better.



The extreme spread was a little better than all the other powders Ive tried in TCM but still not that great.
however....... they did shoot great!!! 5 rounds under 1/2 MOA.

3196fps, 3211fps, 3198fps, 3228fps, 3148fps



The Blitzkings shot much the same sub inch as with the other powders but again the ES was a little better:

3047fps, 3052fps, 3066fps, 3081fps, 3067fps



I will try some more groups with the Vmax backed off to about 3050fps to 3100 as this seems to be where all the powders run without excess pressure.

Here's the tiny .22 TCM next to the humble .22 Hornet for size comparison.
Their ballistics are quite similar but although both cartridges share very similar case capacities the powders and charges seem to act quite differently.

My ES was still around 40fps when I changed to 300mp in my K Hornet. Was all over the place with lil gun.
I improved it by way of annealing, primer and running a homemade button thru after sizing as my dies run a very tight neck.
I put it down to a small case thing but my ES is depending on day 15-25fps. Not as good as my other centerfires but good enough for as far as I will shoot it.

I run the 40 vmax as well at 3100fps. They're a bit too efficient on soft game tho

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@R93 Yes I am starting to pin a lot of the velocity spread on the idiosyncrasies of the small case. The TCM has a very thick neck due to its parent case being .223rem so neck tensions are very tight. Also just like hornet, tiny variations in powder charges or primers equate to big changes in velocities.
Flat based bullets have been a real challenge to seat concentric so many of them will be meeting the lands off center. The first 5 shots or 40gr V-Max show real promise so Ill continue working up a load with them.

I also need to get my hands on some Nosler varmageddons as they have a nice little boat tail too.
Although I built this rig primarily as a intermediate range varminting platform, I should probably see how the 50-55gr bullets go too.
All in all its a neat little round that would be useful in all the same areas a .22 hornet is and in some scenarios maybe perform a little better.
Did you find the 300MP cleaner in hornet too?

i am curious myself on how the 50grn bullets will work, i think the 55s will be to slow for Varminting but maybe good for Goats etc . . . lookn forward to your results to find out

be interesting to compare 40 vrs 50s once you have the data . . . will the higher velocity give the 40s the edge on paper and in the field at longer range . . . so much to look forward to.

the thick neck on the TCM is a worry . . . i would be looking at neck turning with a chamber to fit them

So I decided to leave the Brno 465 Hornet alone after checking out the magazine for TCM. The 465s shorter action and forward mounted ejector compared to the Brno .222 and CZ 527 is an advantage for the TCM but the TCM cases are too large in the diameter to fit in the 465s mag even with mods to remove the side pressings.
This would mean running The 465s shorter action with the .222 or .223 bottom metal and magazine to feed the TCM winch would in turn leave at least one rifle unusable in parts in my collection which Im not keen to do.





Instead I decided to leave it on the .223 action and modify a spare .223mag to feed the TCM rounds.
After a lot of meaasuring up and feeding dummy rounds to see exactly what needed to be done I puts some plastic in the mill and made a rear spacer block of 14.5mm wide.
I milled some slots into the side which locate it snugly on the slot pressings in the mag.







I then made up a new shorter follower to suit and cut a piece of .22 magnum mag spring to fit in the narrower channel.
final mod was to shorten the feed lips back 3mm to match the lips on the .222 mag, this lets the cartridge pop up vertically earlier into the controlled feed extractor before it starts riding up the feed ramp and casing misalignment issues with the extractor.
Ill touch up the bluing and stamp .22 TCM on the top of the follower and it will be done. It holds and feeds 5 rounds of TCM flawlessly now at any speed.

Originally Posted by rossi.45

i am curious myself on how the 50grn bullets will work, i think the 55s will be to slow for Varminting but maybe good for Goats etc . . . lookn forward to your results to find out

be interesting to compare 40 vrs 50s once you have the data . . . will the higher velocity give the 40s the edge on paper and in the field at longer range . . . so much to look forward to.

the thick neck on the TCM is a worry . . . i would be looking at neck turning with a chamber to fit them

Not really a worry but a annoyance meaning annealing before every load.
Personally if I was to bother neck turning and having to have a custom chamber reamer made to suit the new neck dia, Id be looking at making it .20cal and 40deg improved at the same time. That would be the perfect calibre in this little hot rod, the same weight bullets only faster with a higher BC.

I didn't really have or notice a problem with any powder being really dirty to be fair.
I am curious to see if a bit of internal neck reaming may help with your tight necks and sooty cases?

I agree the 465 mags are limiting.
I have single fed a few rounds I loaded long and had slightly better accuracy with the 40 vmax.
But it is still plenty good enough at mag length.

I have shot a couple deer with the 55 hornady soft points and a couple with 45 sierras. (Clean shots inside 100yrds) the sierras seemed to do more damage so I will stick with those.
I have a heap of 50 vmax that I got of another forum member that I will try when I have some brass freed up.

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It seems this 20" Shilen barrel really likes the 40gr V max projectiles.. it doesnt seem to matter what powder/velocity or how bad the extreme spread is.. at 100y they just keep cutting tiny ragged hole groups.

I revisited the slower burning 2205 yesterday with the vmax as I noticed a trend of higher velocities with those bullets.
A max compressed load of 12.2gr of 2205 is still a low pressure load and shot this 5 shot string from new unfireformed brass.

3032
3092
3027
2964
2981

This powder would benefit from a longer throat so I could seat the projectile out a bit and get a bit more powder in without compressing it.
It was my go to powder in .22 K Hornet and always gave good results. Looking at these speeds Id say I could get 3300fps from it if I could get a bit more powder in there.
Its looking like Ill be setting it up to shoot the 40gr and 50gr V-Max exclusively so pushing the chambers throat forward 100-120 thou could be the go.
a longer throat will mean less pressure on my max loads with the other three powders too which are not even close to compressed loads.
I was hoping Aliant 300MP was going to be the answer to a slower burning powder that filled the case but it can still blow a primer out without a full case of powder. 12.5gr seems to be the sweet spot for it giving 3100fps. Other than its much cleaner burn it acts almost identical to H110.

ok .... I seem to recall reading article (will try to find it again) about the hornet behaving much better when fed pistol primers...... much tighter groups and velocity spreads if memory serves me correctly...... this hot rod might be way to hot but could be worth looking into...will go digging for article now.



http://www.shootingtimes.com/ammo/am...motaip_200909/

@Micky Duck thanks for that, ill give some a try too..
I selected SR primers after following the trends in USA forums who are reloading TCM pistols but I guess I wont know if I dont try..

Tested the TCM on a soft target this morning.. 185 yards with a 40gr V-Max.. seems to do the job...

Originally Posted by Wingman

Tested the TCM on a soft target this morning.. 185 yards with a 40gr V-Max.. seems to do the job...

Brutal

good to see you left the back straps and able to be removed for cook up..... looks like a mighty effective wee round.

is this rifle going to get a dial up scope on top in the future or are you going to keep it as a medium range light varminter ?

Originally Posted by rossi.45

is this rifle going to get a dial up scope on top in the future or are you going to keep it as a medium range light varminter ?

Both...
Still waiting for my picatinny adaptor to show up from usa to fit the bigger rings and glass