New Major Caliber: 7.62 TKO from Uronen Precision

    At Rifle World Shoot 2019, I managed to get a few words with Kim Leppänen and another shooter from Estonia who has started using the 7.62 TKO by Uronen Precision.
    Kim Leppänen is a member of the Finnish Semi-Auto Open Team (yeah, they won Gold as usual) and below he shares his first thoughts about a new caliber, called the 7.62 TKO.
    The purpose of using this type of ammunition instead of the .223 Remington everyone else uses, is to get into Major Power Factor, where you get higher points for less optimal hits than Alphas. This way your score can “survive” a Charlie or Delta hit better. (+1 point versus minor scoring).
    The drawback is of course higher recoil, so that your shooting may get slower. As always, it’s a balance.

    The picture reference about calibers is for the top picture in this article:

    I have been asked about my major caliber so much.. Well here it is. 7.62 TKO.

    From left there are normal .223, 7.62 TKO and .300UP. 7.62 TKO case is 39mm long and it uses .308” 147gr bullets with Reload Swiss RS36 powder.

    The Power Factor is 333.

    Is it game changer? It’s up to you! It has a lot of more recoil, but maybe not too much for fast shooting.

    I think that IPSC rifle shooting is kind of boring, because you need to hit the Alpha zone only.

    With this solution you have options for different styles of shooting.

    It will take time to get used to it, but I see that this is as good as .223 but in different ways. Shooters that are against Major power factor have not usually even tried to shoot with major guns and still have a lot of opinions.

    Below: 7.62 TKO needs magazine made for long 7.62 ammo.

    A bit of the history and backgroud, check out the .300 Uronen Precision caliber we reported about earlier.

    Some data, provided by Uronen Precision (Finland):

    For information, the Power Factor in IPSC Rifle is a minimum of 320.

    Power Factor 332 with 147 gr bullet, with low pressure 3700 bar.
    With max pressure it makes about 360 power factor.

    With 155gr bullet from 18” barrel, it exceeds requirements for moose hunting in Finland (2000 joules at 100 meters with minimum 10 gram bullet).

    Ballistic performance from Uronen Precision 18” barrel:

    Hornady 110gr V-max 2850 fps 870 m/s
    Hornady 125gr HP 2600 fps 795 m/s
    GGG 147gr FMJ 2400 fps 730 m/s
    Sierra 155gr MK 2350 fps 715 m/s
    Sako 175gr HPBT 2175 fps 665 m/s

    The test rifle is an UP AR-15 with 18” barrel, with mid-length gas system and UP aluminium bolt carrier.

    It makes the major category with a 125gr bullet, but 147gr bullets are cheap over here (in Finland) and it makes it a cheaper option for major ammunition.

    With RS 36 powder it gives quite low pressure, and Major Power Factor with 147gr bullets.
    Even a 14.5” barrel can make major power factor, but requires full power load.

    One of the goals was to make it possible to shoot major power factor in rifle competitions with affordable ammunition.
    So how compatible is 7.62 TKO it with the original .300 BLK? Can an AAC chamber be reamed to .300 Uronen? According to Uronen Precision the freebore is much shorter, so it can be done, .300 UP – .300 BLK but not other way around! The new caliber can be shot from Uronen Precision .300 VLK or .300 UP barrels, but not from all .300 BLK barrels.
    Another target was to make brass forming easy: just resize and trim. It should not take more time than preparing brass from a .223 Rem.
    Most .223 and 5.56 cases can be used. No neck thickness problems like with .300 BLK. Just resize and trim .223 and you have 7.62 TKO brass.

    Uronen also tested 18” mid-length .300 BLK barrel with low friction rifling. It made major PF 100% safely with 168gr bullets, but lighter bullets created too high pressure for reliable functioning.

    For more info and details check with Uronen Precision.

    What do you think about Uronen Precision 7.62 TKO? A crazy idea or the beginning of something new?

    Eric B

    Ex-Arctic Ranger. Competitive practical shooter and hunter with a European focus. Always ready to increase my collection of modern semi-automatics, optics and sound suppressors. TCCC Certified medic.


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