Finnaccuracy takes their 375CT Sako M10 to 4380 yards

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A detailed look from the guys at FinnAccuracy shooting their 375CT SAKO M10 at 4000+ Meters or 4380 Yards. Go behind the scenes and see exactly exactly what went into making this shot.

We did some shooting, and we did hit 4005-meter target. That’s 4380yards or 2.49 miles for those living in imperial unit part of word. For starters- as I have received quite a few inquiries and some congratulations about new distance record: Firstly- to even break a record, it would require having some kind of rules that everybody must follow. Secondly- how to determine that shot or trials were comparable? I don’t know. Air pressure will only make big difference with +10 sec flight times, and we unfortunately did not get any advantage from it. We are located in pancake-flat country by the sea. It also makes a slight difference with difficulty if 5, 10 or 20 shots has been taken before even hitting anything smaller than barn wall.

Way I see it, if the hit is done with one-man portable rifle and supports, it’s done within couple of shots, and the impact is close enough to disable or at least scare living daylight out of an imaginary person standing against target, story might be worth sharing with others too.

In Short, we don’t care about what somebody else somewhere has done. This is the Policy that has suited us Finns well before. We just wanted to see how far we can reach with the setup we happened to have. Still, and to be honest, we dragged our target to a further distance that some who has announced having world records have ever shot. But not so much because of “records”- just for Shits & Giggles.

This being said, hopefully we get more people pushing limits. With the right setup, enough knowledge and enough people trying it, even longer ranges can surely be done. Our motto was and still is to use normal stuff and commercial gear whenever available – meaning factory ammo, rifles, mounts etc.

This was sort of exception, as we built 375 Cheytac on Sako TRG M10 ourselves and factory loads are simply not available. At least here. But still, it’s pretty close to standard rifle anybody can purchase. Only barrel is changed, bolt head is opened slightly, as well as ejection port is larger. That’s it. Bipods, stock, trigger all exactly as they came from Riihimaki factory. TRG M10 action has proved to be unbelievable strong – and we have proof tested it with Cheytac overpressure 5500bar / 80000PSI cartridges with no problems. Headspace has also been checked after shooting pile of +10000 Joules / +7375 ft lbs loads, all ok.

But still. TRG M10 action size is scaled accordingly to 338 Lapua- class cartridges and Cheytac is above this. We do NOT encourage anyone to do same. Safety margins are much larger with dedicated Cheytac actions. +130gr powder charge energy guarantees very bad day to anyone who do silly things, intentionally or unintentionally. One can imagine AR15 catastrophic failure videos. Multiply explosion energy by 6, and you’re in ballpark how bad a day could be if something goes wrong.

All in all, this was still kind of a milestone to us, on road that basically started already 2003. Both I and my colleague were both curious to get hold of LR ballistic side. Then soon after, business related to high-end optics came along when Finnaccuracy was founded. Optics weren’t available- or rare dealers selling them did not have a clue what they were dealing or what our type of customers even need. From day one, we concentrated particularly on practical long distance precision shooting. We have expanded to various products since, but military type sniper shooting was and still is our bread and butter, and also what we love to do. We do not shoot groups or tow 25lbs $20000 candy-painted custom rifles from trunk to concrete bench. Way we see it, rifle has to be practical and carryable.

The last time we did something similar was when Lapua´s radar data was not publicly available, early 2008. Quick Target Unlimited with Cd- drag files proved itself then to us. We were using bone-stock original Sako TRG-42 and Lapua 250gr Scenar factory loads, shooting first-round hits 1000-1400-1600 and ending up with 2nd round hit at 2003 meters or 2190 yards. Target was 45cm wide and app. 120cm tall (app. 18”x45”) reactive plate. The Most amazing part, for us at least, was that first time we had access to software that actually takes impacts to target right away on ELR (then), IF input values are right. Naturally- then and now- there is always some luck involved. When target is smaller than theoretical group dispersion, quick prayer to trajectory gods is appropriate thing to do before sending any bullets. But all in all, long range marksmanship is about minimizing variables that can be effected. Bye bye PCB 1.0!

So, long range field shooting has always been a passion to us, and therefore this was somewhat rewarding feedback. But to be honest, it was not only us. We are basically only a visible tip of iceberg inside Finnish sniper shooting community- on both active and reserve side. I even dare to claim that average knowledge and skill level compared against anybody is extremely high, thanks to long Finnish tradition in marksmanship and well organized reserve sniper shooting courses. Especially few individuals have pushed things forward to modern direction both in civ/reserve side and active duty/training side.

Thanks and part of credit goes to whole Finnish sniper shooting community- as well to professionals from various companies. Sako and Lapua have been actively developing products for LR/ELR community, and were involved in this particular event too. Special thanks to them as well.

Weekly portion of dramatic prefix should be filled now- gear list and how it was actually done.

Rifle:

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  • Sako TRG M10 base rifle.
  • Finnish Peurala CrMo barrel with .375 CIP dimensions. 10” twist, 31” length made from 32” blank. Final slug check / hand lapping done by me.
  • Terminator T4 muzzle brake.
  • Chambering: standard Pacific Tools 375 Cheytac reamer.
  • Support during shooting: prone, TRG 42 bipod with Finnaccuracy M10 bipod adapter. TRG M10 adjustable monopod.

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Ammunition:

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  • Cases Bertram 375 Cheytac (lot with malformed shoulder..), 3rd reloading cycle, necks annealed after 2nd round.
  • CH4D dies- neck sizer only used so far.
  • Cutting Edge Bullets, 352gr MTAC, COAL to 0.1mm / 0.0039” jump. G1 0.890, G7 0.408 according to Applied Ballistics measurements.
  • Primers Federal 215 – normal, not match grade.
  • Powder Vihtavuori N570, 2015 lot. Charge 126.5gr.
  • Muzzle velocity (climbed during day) final string with 936mps / 3071fps average.

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Rifle optics:

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  • Hensoldt ZF 3.5-26×56, std reticle.
  • 22MOA picatinny riser with improved recoil stopper.
  • Recknagel adjustable 0-70MOA mount with app. 115MOA mod.
  • TRG M10 30MOA integral rail.
  • Total cant approximately 167MOA.

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Other:

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  • 4 spotting scopes: 3pcs of Zeiss Diascope 85, one Zeiss Diascope 65 with Finnish army fine milling reticle on 30x Wide Angle eyepiece.
  • Steiner Military LRF 8×30 R SUMR, Vectronix PLRF 10 + 15.
  • 3 pcs of Labradar velocity radars.
  • Military / artillery grade laser range finder.
  • Tracker Android GPS + maps, with GPS+Glonass support (non-differential, accuracy under 2 meters).
  • Vaisala VM30 wind sensor (used in firing position).
  • Field laptop with Quick Target Unlimited v. 3.9.
  • Android Shooter used too on side, for comparison.
  • Several Kestrel weather stations.
  • Towable target frame.
  • Wireless Kongsberg acoustic target system (used on 1000m zero verification, max range app. 1000m).
  • Crew: Shooter, ballistic field office manager, forward observer, 2 spotters located on firing point. One person verifying/logging set values + tracking sent projectile MV:s from radar.

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Links:

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  • www.finnaccuracy.com (Organizer- optics, lasers, ballistic software, mounts, M10 accessories).
  • www.sako.fi/defence-law-enforcement.
  • www.lapua.com.
  • www.vihtavuori.com.
  • www.peuralanasepaja.fi (Peurala barrels).
  • >www.pacifictoolandgauge.com.
  • www.cuttingedgebullets.com.
  • www.ch4d.com. (dies)
  • www.mylabradar.com.
  • www.kongsberg.com.
  • www.hensoldt.de.
  • www.zeiss.fi.
  • www.steiner-defense.com/.
  • http://www.vectronix.ch/.
  • www.vaisala.fi.
  • www.kestrelmeters.com.
  • www.recknagel.de.
  • www.terminatorproducts.co.nz.
  • www.tracker.fi (GPS + maps application).
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    The Event started with last day changes, how else. Not sure if this part of story is too interesting- but as everybody ever competed know, something will with no exceptions go wrong just before important event. Destiny did not fail me this time either, but we had to do it as participants had arranged spots in very busy calendars. More about this on our pages, will try to keep this version short. Full version with mishaps will appear to our pages later. Shortly said, original plan was to shoot with S&B PMII 3-27 with 34mrad turrets.

    Shooting day

    We started with 100 meters zero, and checked same time our other TRG M10 with 338 Lapua Mag barrel for Lapua Scenar 300gr factory load tests. We were curious to see how this latest Scenar works beyond 2000meter mark. This rifle was equipped with Schmidt&Bender 3-20 Ultra-Short, also offering large 34 mils travel from latest low profile double-turn MTC/LT turret. Scope was installed with IEA modular KH QD mount, 60MOA cant wedge. This added to M10 integral cant picatinny, total was 90MOA.

    375 Cheytac zero was done with five shots. Scope turret bottomed to zero, impact was 26.8 mrads high. Last two after windage adjustment were very close each other. This elevation was used as base for further calculations, as zero POI offset value in ballistic application. Just before shooting started, I found out that my bubble level was sitting on table back home. This was serious setback. During both zeroing and shooting, reticle and rifle must be in absolute vertical level. This was difficult, as there wasn’t horizon reference visible. Velocities were compared constantly, with each and every shot. In beginning, we had several Labradars pinging side by side. This was to ensure that none of our new units happened to be Monday-morning special giving silly readings. All showed identical velocities, so we had confidence to pick any of them and proceed with single device only.

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    1000m zeroing

    After zero was done, we hauled our basecamp to 1000meters zero check distance. Meanwhile, also Kongsberg acoustic target was prepared for use. This saved lots of time- and shots too. For reasons mentioned in full version of story, I was trying to keep shot count in absolute minimum. Luckily I realized that my CTK all-purpose gun level could be used on rifle during shooting. I happened to have it with me for scope installation we did previous night. Integrated sturdy rubber cord seemed strong enough keeping level in its place during shooting, as it did too. First 1000 meter shot aiming trough sight reminded that something unusual was going on. 1000 meter zero was on reticle upper portion, about 20mils over center cross when turret bottomed to zero. When aiming and seeing target on top portion of reticle, ¾ of FOV was on close proximity terrain. Silly view!

    5- Shot fairly good grouping string proved elevation to be correct and exactly where we expected it to be. Windage zero was 3 clicks off, error very likely caused by unintentionally tilted rifle on 100m zero. It was a mishap costing extra rounds in next 3000m range we went. Hensoldt turret zeroing requires loosening big flat-head screwdriver like nut on top of turret. Same design was originally presented on Finnish Army Sako TRG42 Zeiss Diavari scopes, and it can be tricky. Locking nut head is designed to fit 338 Lapua Mag case head rim. Machining and dimensions are spot on, but case head grip is far from proper big screwdriver- and case has to be pressed sideways against nut hard. I have done this dozens of times with army scopes. Problem is that turret must be hold absolutely still with one hand, while (often) unnecessary tight nut is turned counter-clockwise with other hand holding case as a tool. And classic thing happened- same time tight nut opened, counter force of fingers holding turret rotated it to right unknown amount of clicks. After several carefully assorted curses, I decided to leave it as it was with no further adjustments. Just careful tightening to prevent further damage.

    After successful zero (with a small blemish), we moved our ballistic base camp to actual shooting point. Barrel got some TLC in this point too, few wet patches followed by several dry ones.

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    Cleaning after verified zero

    Next distance was 3000 meters or 3281 yards. Terrain spot was higher, so we needed to get idea of wind and other related effects. Ballistic software was truly benchmarked too first time. We had used QTU successfully before on extreme ranges, but only with Cd radar data. At this point, my favorite general-purpose looking glass Steiner Military LRF 8×30 SUMR laser bino was not enough with app. 2000meter ranging capability. Same happened with Vectronix PLRF 10C, it stalls at around 2500meters, and 15 does did not go much further. We proceeded with GPS + maps and mil-grade LR laser.

    Wind was coming almost behind, average 7 o’clock. Magnitude 2-3 meters per second or 4-6 mph, so not too strong but still gusty. Mirage was moderate, air temp was 18C (64.5F) in beginning and warmed soon to 22C (71.6F). Mirage changed from small to moderate, but there is always some mirage with such a long range in summertime. We got elevation sorted close with a few shots even with restive and raising muzzle velocities, but windage took bit longer time. This was partly because of messed up turret, partly because finding out effective side wind average with uncertain or not-seen impacts. Spotters- especially other one, was also very experienced, but calling winds for such a long distance was new thing to learn for him too. I was basically blind monkey flipping a switch instantly when told to do so: Elevation needed for 3k was already so much that I was shooting with low magnification and plenty of hold-over- not much chance to see details from tgt area. Besides, I had my hands full keeping rifle still on target- aligned and in perfect level same time. Comfortable prone position is hard to achieve when muzzle is literally pointing towards sky- buttplate angle against shoulder was silly, not to speak of cheekrest as scope was very high.

    We had Vaisala VM30 wind sensor which turned out to be excellent aid- but when looking bullet path with spotters, mirage was changing directions every now and then. With ranges this long, even several opposite wind directions can easily happen. Main thing was still to keep eye on shooting point Vaisala, as roughly 50% of total windage deflection form in first third of trajectory.

    Shot count was 15 when we got everything finally sorted and good hit on target. Good meaning that everything matched. That particular shot MV was same we used on ballistic software and actual elevation adjustment matched perfectly to QTU firing solution on same time. Also most importantly and with that particular shot, I knew shot was good. As mentioned, maintaining readiness and bubble where it should to fire in 1-2 seconds after permission from ballistician-on-duty was extremely cumbersome thing to do. We did not use heavy sandbags or other methods not belonging on to true field rifle- just original TRG42 bipod and M10 original monopod. Which is excellent by the way.

    Also MV deviation was settling down in last 5 shots, although higher than expected. Could be caused by barrel temp, pre-heated cartridges in chamber or something else. Cartridges were never chambered all the way while waiting wind to settle within pre-adjusted corrections, but some heat may still transfer during pauses. As ammo count was decided to keep as low as possible before 4000 meters, we stopped there. Case ejection was also giving warnings in form of light jamming, so it was really pointless to continue.

    ?Morning started with around 925mps / 3035fps, and now highest individual shot was already 3084 fps or 940mps. Further calculations for final 4k push were adjusted according to average 936 meters per second (3071 fps) assumption. Each meter per second (3.3fps) change on MV would cause 0.2mrad (80cm/31”) vertical POI shift at 4000 meters. Coriolis Effect only shifts impact 0.6mrad / 2.4m / 2.6yds with 4000m fight times by the way, so there was really no room for unpredicted changes. Atmospheric conditions were 22C/71.6F, 996mbar/29.41inHg/RH 78%, DA 513meters/1682ft.

    As we had statutory refreshment pause (except poor crew member hauling target 1000m further), I decided to play around with Android Shooter same time. Just to see what is says. With verified 3000m POI, I had to use much higher BC than A.B. verified .408. Otherwise firing solution seemed to make sense.

    Tapped in next range 4000, and realized instantly that we are in trouble with elevation correction. Android Shooter solution was over 100 mrads (its +1000 clicks btw) of elevation, and from top of my head I was uncertain if it could be even arranged. Hensoldt 3.5-26 has smaller FOV than originally planned S&B PMII 3-27, meaning less room for silly amounts of hold-over.

    Took a look through scope and crunched numbers for exactly required hold-over, and realized that only way to get it was to go almost lowest 3.5x magnification in order to see enough reticle. Luckily, target was made rather big for this particular reason, being 2.4 x 2.4 meters or 2.6yds square piece of art cardboard. One of our crewmembers even politely painted huge bright crosshair on it, leaving trigger monkey no uncertain feeling where exactly to aim it.

    Same time, target was fine-positioned and checked for clear line of sight, and first time I realized how long distance it actually was. It was far, ridiculously far. Very hard to even see with bare eye, but surprisingly still ok visible with 3.7x (or so) magnification. Target was ok, and we received permission to shoot.

    finnpicture3

    Rifle pointed exactly at 4005m TGT.

    For first shot, I took correction from Android, using “calibrated” BC. Impact not seen or heard, by spotters or FO. We stopped there and thought it through. MV was low, couple of meters per second under ballistic solution assumption. Meanwhile our on-duty-ballistician also appeared on site, he was meditating in he’s Olympic Opel (Audi) command vehicle. He crunched numbers again for 4000 with QTU and result was over 2 mils more elevation. First shot had to therefore been way low- correction and MV of particular shot were both in same direction.

    Second shot was sent, and about ten seconds later firing point spotter catched 90% certain splash just next to target frame. Also that individual shot MV was close but little under target velocity, so very likely it was so. Third and fourth rounds were sent in rapid pace to same wind. Right after, FO informed with radio that he had heard something after these shots. He was not in close proximity to target, so he wanted to check target. Shooting was stopped and we waited.

    And there it was, a clean round hole in cardboard. 40cm (15.7″) right and 60cm (23.6″) high from center.
    To be honest, it is uncertain if it was 3rd or 4th shot that actually was a hit. But later, after examining MV:s of string, 3rd shot MV was very close to predicted, and 4th shot should have been over 2 meters / 2 yds high. So with good probability it was particularly 3rd that made the hole.

    After small moment of circular back-tapping and couple of high-fifes, we sent 2 more rounds downrange. MV:s were still high, continuing in same level with 4th shot. Also case jamming was getting worse, so we decided to stop. Purpose of trial was achieved, and there was possibility that jamming is caused by excessive headspace. And we had no way to check it. After all, we had been beating TRG whole day with rather warm +10000 Joule / +7250 ft.lbs loads whole day, so better safe than sorry. Shoulder bumping seem to take Bertrams to 3rd reloading round fine, but not further. M10 headspace was checked later, and it passed it (again) with flying colors.

    finnpicture4

    A hit! 4 fingers, 4 kilometers.

    finnpicture5
    finnpicture6

    Perfectly round hole, punched by 100% stable bullet. Easily enough remaining energy for any soft target.
    Normal 0 false false false false FI X-NONE X-NONE

    Sniper’s Hide Note:

    Thanks to the guys from FinnAccuracy for sharing their story, a few minor changes were made from the original content as English is not their first language.