Ben

1000 Yards with the .224 Valkyrie

I took the .224 Valkyrie out to the 1000 yard line on Thursday at Douglas Ridge Rifle Club in Oregon. It’s about time I got to stretch the Valk’s legs. I was shooting the 95 SMK in a Bison 24″ 1:6.5″ twist barrel. My muzzle device was an Elite Iron brake that I normally use with their Bravo 1 silencer but my DOPE for my previous sight in was taken without the silencer so I kept it like that for this session. Here’s the view from the targets looking back at the firing position:

The target positions are behind me. The targets in front are for 200 to 600 yard service rifle competitions. Here’s the view from the 900 yard firing line:


Turns out it helps to get on paper to know which firing line you are at. I thought I was at the 800 yard line and I ended up wasting quite a bit of ammo getting on paper. Checking against my DOPE and ballistics data I was quite puzzled at the almost 7.8 mils of come up needed to get on paper when I had computed something more like 6.8 mils were needed. Thanks to the low recoil of the .224 Valkyrie I was able to see the rounds hitting the dirt which told me I was a ways off. Wasting ammo with my bald spot blasted by the late afternoon sun wasn’t my idea of fun. But I did get on paper and then back to the 1000 yards line we go. Shade is a good place to shoot from.


The .260 Rem got to try 1000 yards too. The DOPE for that one was way off as well, you’d think that would have told me something. I got on paper and then changed targets. I should have taken a photo of the Caldwell Target Camera LR system that I was using. This thing was the best $350 I’ve spent in a while.

 

I have no Android or iOS devices So I had to improvise. You can log into the camera through a website. The IP address of the camera is marked on the side, which in my case is 192.168.0.3, and then provide the username admin with the password 12345 and you get to a menu written in Chinese. Selecting the second item in the menu gets you to the live feed from the camera.

A note about this system: I couldn’t see a single hole in the target black though I hit it several times. Hits in the white are clearly visible. I recommend using these targets for 1000 yard shooting with the Caldwell Target Vision camera system:

 


I haven’t used this target yet but I think it will work well. It’s 42″ square and I think light enough to see the bullet strikes. I was using white cardboard which worked really well too, but didn’t cover the target black behind it completely so it I could not make out the bullet holes that were not in the white. I’ll report back after my next session later this month about how the IBS targets worked out.

As one might guess, getting on paper at 1000 yards given my confusion about which line I was shooting from at 900 yards, a little work was needed to get on paper at 1000 yards. Again puzzling because once on paper my come up was 9.2 mils when I had expected 10 mils from my ballistics computations and then probably more given the 7.8 mils I thought I needed at what I thought was 800 yards. Both the .260 Rem and the .224 Valkyrie were consistently inside 12″, which is pretty good for me given that I’d never shot at this distance before. Winds were consistently inconsistent but at about 5 mph. The direction changed often and sometimes died out completely only to come back again 30 seconds later. First time out at 1000 yards, the range all to myself, what’s not to like:


Holy mackerel, my nose isn’t nearly that big in real life, I swear! Now that I’m dialed in, I’ll be shooting some groups my next outing instead of just spraying all over the target while constantly adjusting my windage and elevation. Conclusion: .224 Valkyrie can shoot at 1000 yards. Next time: 80 SMK loaded to about 2850 fps in the 24″ barrel. Oh yeah, after wrapping up for the day I noticed that the 800 and 1000 yard berms were really close together. That’s when the dam broke and I realized I’d been shooting at 900 and not 800, argh!

.224 Valkyrie 95 SMK

I finally got to test some 95 SMK hand loads. I used Winchester small rifle primers, new Federal brass, and Winchester 760 powder starting at 26.0 grains and working up to 27.5 grains. The rifle has a 24″ 1:6.5″ twist Bison Armory heavy barrel and an Elite Iron muzzle brake but I left off the silencer and shot unsupressed for the testing.

I only shot a single 5-shot group at each charge and got the following average velocities with standard deviation below 13 for all and extreme spread no greater than 27:

26.0: 2430 fps

26.5: 2510 fps

27.0: 2555 fps

27.5: did not measure, estimate 2600 fps

I shot the first three loads at 100 yards and shot a near 1/2″ group with the 26.5 grain load:

 

 

 

 

 

 

 

 

 

 

 

 

 

2510 fps at the muzzle with a G1 BC of 0.60 results in 1318 fps at 1000 yards and 1168 fps at 1200 yards. The speed of sound is around 1130 fps and this load stays above that to 1250 yards according to the G1 BC and available data. The load is definitely a 1000 yard performer in terms of velocity. Hopefully I will get to shoot it at 1000 yards this summer. Pushing to 2550 or even 2600 fps seems reasonable, though accuracy wasn’t quite as good as I pushed the bullet faster. Single 5-shot groups are not sufficient to make a firm determination but more testing is in order.

I am thinking that Federal’s 90 SMK accuracy troubles may result from loads that are just too hot. I wonder if they’re pushing the bullets too hard to get the mythical 1300 yard supersonic performance but sacrificing accuracy. Seems like a lousy trade to me when solid 1000+ yard performance from a 75 to 95 grain bullets is great performance from any AR-15 rifle.

 

 

 

224 Valkyrie Ballistics

Bison Armory will have new .224 Valkyrie rifle ammunition available to the shooting public early in May. We have come up with two loads to start with, using 75 grain Hornady ELD and 80 grain Sierra MatchKing bullets. The reason for this bullet choice is that many or most 1:7 twist barrels are struggling to shoot the 90 grain Sierra MatchKing accurately. Now what is the point of a particular load that will shoot 1300 yards if it won’t hit the target?

Alternatively, I have found the 75 TMJ offering by Federal to be very accurate in Bison Armory 20″ .224 Valkyrie barrels. And muzzle velocity of 2890 fps from that barrel is good too. However, the 75 TMJ has a G1 ballistic coefficient of 0.35 which is nothing to write home about.

We figured there must be something better than these two suboptimal loads for the .224 Valkyrie. To that end, I investigated the heaviest bullets available that would stabilize well with a 1:7 twist barrel, and the 75 grain ELD and 80 grain SMK are at the top of the list. The 75 ELD has a G1 BC of 0.467 and the 80 SMK has a G1 BC of 0.461. These ballistic coefficients are tame compared to the 90 SMK G1 BC of 0.563, but the 20″ barrel can only push that bullet to 2630 fps.

With modest loads I am able to push the 80 grain SMK to 2780 fps and the 75 ELD to 2830 fps. Faster loads may be attainable, but these are where we’re at with safe loads now.

Time to compare performance. The following charts are extremely interesting:

Trajectory comparisons over 1400 yards don’t look very good. So here I’ve subtracted the 75 TMJ drop from those of the other three projectiles. Notice out to 900 yards the 75 ELD and 80 SMK have less drop than the 90 SMK from a 20″ barrel (in this case less drop is the same as more “drop delta” i.e. the difference between the 75 TMJ and the projectile in question). Notice also that the 90 SMK doesn’t surpass the 75 ELD until 1200 yards (this is not entirely true, as the 75 ELD went subsonic a little before 1100 yards, and thus after that point would have dropped more than shown here). So we see that at effective ranges out to almost 1100 yards, the 80 SMK and 75 ELD are keeping up with the 90 SMK just fine.

Here we plot the velocity data for all four projectiles. The 75 TMJ has a significant advantage in muzzle velocity over the other 3 loads, but it gives this advantage away before even 100 yards due to its much lower ballistic coefficient. The 80 SMK and 75 ELD both have good muzzle velocity and superior G1 BCs and they perform much better. The 75 TMJ drops subsonic (by my definition, using 1130 fps, not worrying about transonic effects, comparing all projectiles against the same metrics, etc.) by about 850 yards. Now I rarely shoot at distances greater than 600 yards, and the 75 TMJ shoots very accurately for me and is cost effective. So for general range time, it’s a fantastic round all things considered. However, when trying to push out to 1000 yards, it doesn’t cut the mustard.

The two new commercial loads that we are producing at Bison Armory, on the other hand, give true 1000+ yard performance and will shoot accurately in 1:7 twist barrels that struggle with 90 grain projectiles. If you can shoot the 90 grain accurately, you can see that the 90 SMK surpasses the velocity of the 80 SMK at 400 yards, and the 75 ELD at about 600 yards. The two lighter bullets maintain their flatter trajectory to 1000 yards, but they lose in velocity, which translates to energy as we’ll see next.

And now we’re where the rubber meets the road. Nothing says real world performance for hunting and defense like energy. All 4 loads considered are similar out of the gates, but the 90 SMK is markedly superior beyond 100 yards compared to its three slimmer brethren. The 75 TMJ can’t keep up at all, and past 200 yards it is in a different universe of kinetic energy compared to the other three loads. The 75 ELD and 80 SMK, while well below the energy of the 90 SMK, are well above the .223 Remington, and I consider their performance to be excellent. Flatter shooting but less energy is a trade off I can make. Combine that with sub-moa accuracy that I’ve been getting reliably with the 80 SMK and 75 ELD, and we have a pair of winners for anyone shooting .224 Valkyrie.

The 80 SMK load is available for pre-order at Bison Armory and the 75 ELD will be available for pre-order soon. Both loads will start shipping in early May 2018.

Update:

We tried the 79 grain Cutting Edge bullets and they don’t stabilize in 1:7 with our 20″ barrels either. Going to try them in the 1:6.5 twist. Additionally, finally have some 80 grain ELD to see what they will do. Will report back in a couple weeks when we have data.

 

.224 Valkryie 80 Grain SMK Match

New .224 Valkyrie ammo brought to you by Bison Armory. We’ve teamed up with the Washougal River Cartridge Company to produce match grade .224 Valkyrie ammunition specifically designed for 1:7 twist barrels. Using Starline brass and pushing the 80 grain Sierra Matchking bullet to 2780 fps from a 20″ Bison Armory barrel, we’re getting excellent accuracy and keeping the bullet supersonic to 1100 yards. Available early May 2018, pre-order now!

Bison Armory .224 Valkyrie Barrels Coming Soon!

We’re bringing Bison Armory quality and value to the .224 Valkyrie world with 20″ SPR and 22″ Fulcrum rifle barrels! Barrels are available for pre-order now and should start shipping in March 2018. Upper assemblies will be available when the barrels are in stock. Check here for barrels and here for upper assemblies.

Bison Armory .224 Valkyrie barrels will be available with Stag, JP, and LWRC bolts, and feature the following specs:

1:7 twist button rifling

416R stainless steel

5/8-24 muzzle threads for maximum accuracy

Whitworth Tool (SPR) and BAT Machine (Fulcrum) barrel extensions with M4 feed ramps

Bison Armory 308 Win Upper Assemblies

Bison Armory is happy to announce that we’re finally making 308 Win upper assemblies! We’re using Aero Precision M5 upper receivers that are 100% compatible with DPMS LR-308 lower receivers. Accuracy is outstanding, and you can pair your 16″, 18″, and 20″ .308 Bison Armory Fulcrum barrel with a standard .308 Bolt and carrier or upgrade to JP Enhanced Bolts and LMOS carriers. Forearms from SLR Rifleworks and Aero Precision complete the upper assemblies.

 

The complete upper shown weighs in at 6.8 pounds. Here’s my last 10 shot group using my personal recreation of FGMM 168 grain loads

18″ 308 Fulcrum 42 gr H4895

You can check out our new upper assemblies here! 18″ upper assemblies are available now, and 16″ and 20″ will be available soon.

 

 

 

 

 

 

 

 

 

Youth / Low Recoil Hunting Rifles Part 2

In part 1 of this post last week I looked at recoil and report, as well as muzzle velocity when comparing a typical 20″ .243 Win hunting rifle with a 16″ 6.8 SPC AR-15. Both of these rifles are mild recoiling and excellent for youth hunters, or really any hunter who wants an easy to carry rifle for medium game like deer, black bears, cougars, and hogs. The results shown in the last post indicate that the .243 has the edge in recoil and velocity for 95 grain bullets, though the 6.8 SPC will be a little easier on the ears. In keeping the 6.8 SPC to 16″ barrel length, the addition of a silencer, typically adding 5 to 7 inches of length to the weapon, will be easier to carrier and shoulder than the 20″ .243 Win.

We turn our attention to the down range performance of the two rounds. Since the last post, I’ve learned that Barnes isn’t making the 95 grain .243 caliber TSX anymore so I’ve replaced it with the 95 grain Hornady SST, so all the analysis of the previous posts for internal ballistics is the same. The G1 BC of that bullet is .355, while for the 95 grain 6.8mm TTSX the G1 BC is .292 and the 110 Accubond has a G1 BC of .370.

Muzzle velocity (fps)300 yard velocity (fps)400 yard velocity (fps)300 yard drop (inches)400 yard drop (inches)
.243 Win 95gr Hornady SST BC .35528342108189312.930.4
6.8 SPC 95gr TTSX BC .29227071865162715.837.7
6.8 SPC 110gr Accubond BC .37025311878168717.239.8

The table shows that the .243 Win shoots flat. Most youth will keep shots on deer well under 300 yards, but I’ve used 300 as a good benchmark as that’s a shot you want to be able to make. The 6.8 SPC shooting both the 95 and 110 grain bullets is no slouch and both the .243 and 6.8 will be able to hit game at 300 and 400 yards. How do these rounds stack up in terms of energy?

100 yard energy (ft-lb)200 yard energy (ft-lb)300 yard energy (ft-lb)400 yard energy (ft-lb)
.243 Win 95gr Hornady SST14021152938756
6.8 SPC 95gr TTSX1221953734558
6.8 SPC 110gr Accubond12931060862695
6.8 SPC 110gr Accubond 20" barrel 2600 fps13681124916741

Again, the .243 Win has the edge over the 6.8 SPC, though the 6.8 hangs in there with the 110 grain Accubond, and either of these calibers will take medium size big game out to 300+ yards. Note that in a 20″ barrel where the 110 Accubond can push to 2600+ fps, the energy of the round has effectively caught up to the .243 Win. The tradeoff then is terminal performance vs overall length of rifle. A 16″ AR-15 is very ergonomic and easy for a hunter, especially a youth hunter, to carry and shoulder in the field. The addition of a silencer to the 16″ weapon isn’t as cumbersome as when added to a 20″ weapon.

However you compare them, the .243 Win and the 6.8 SPC both make excellent choices for mild recoiling hunting rifles for medium sized game. Personal preference for energy down range, flat trajectory, rifle size and weight, report sound level, and those intangible aspects like personal preference for a given caliber, are all valid reasons to choose .243 Win or 6.8 SPC. There are of course many other calibers, like the 6.5 Grendel and .300 Blackout in AR-15 platforms, and .260 Rem, 6.5 Creedmoor, and .25-06, etc. in bolt action platforms, that make for great mild recoiling hunting rifles. One thing is for certain, hunting is a great American tradition and pastime, and there is no lack of choices when it comes to rifle calibers that get the job done.

 

 

 

Youth / Low Recoil Hunting Rifles Part 1

Updated June 24, 2017

The 6.8 SPC caliber makes for great medium sized game hunting from hogs to deer to black bears and more. The 6.8 has mild recoil, and a lightweight rifle chambered in this caliber is ideal for hunts in which you put a lot of miles on your feet, up and down in hilly terrain. The mild recoil is preferred for anybody, but especially so for young hunters, women hunters, or anyone who wants a lightweight easy shooting rifle. My 18″ 6.8 is what I choose when I’m hunting deer in central and eastern Washington State. I’m not considering the ultra-mild recoiling .223 because it’s not legal for big game hunting in many states, my home state of Washington included.

The standard youth deer rifle appears to be a bolt action .243 Winchester with a 20″ barrel. I’ve never shot one but I’m told it has mild recoil, which I find surprising given that the .243 Win is based on a .308 parent case. My goal with this post is to compare the 6.8 SPC to the .243 Win. I want to compare external ballistics, recoil, and report / sound level – as every good parent wants to protect their child’s hearing as much as possible. Using QuickLoad as the tool for internal ballistics, and Hornady’s external ballistics calculator for down range performance, we can compare performance against several metrics.

Recoil

For most of us dad’s out there, we want our kids to have fun hunting and shooting. We start them young, and the last thing we want is a flincher because we started them with too much gun. Turns out the 6.8 SPC and .243 Win are great choices for youth hunters and shooters in terms of recoil. To see why we can compare the recoil force due to the impulse imparted by shooting on the rifle and shooter. The entire process of powder ignition to bullet exit at the muzzle takes about 1 millisecond. The force imparted to the rifle can be estimated from the impulse based on the following formula:

    \[ J = F (t_2 - t_1), \]

which is the impulse due to a constant or average force, F, applied over a timespan starting at t_1 and ending at t_2. An impulse is a change in momentum so we can also compute the impulse J as

    \[ J = mv_2 - mv_1 \]

where v_1 is the starting velocity and v_2 is the end velocity, and m is the mass that we assume does not change for this analysis. From the previous two equations we can make the following equation:

    \[ mv_2 - mv_1 = F (t_2 - t_1) \]

And then we solve for the average force that would result from the given impulse

    \[ F = m (v_2 - v_1) / (t_2 - t_1) \]

which, given that v_1=0 and t1=0, and letting t2 = t, the total time from ignition to uncorking, simplifies to

    \[ F = m v_2 / t \]

Report

The magnitude of the report is primarily due to the sound pressure at the muzzle the moment the bullet exits. The ratio of pressures is captured by this expression (using the reference pressure P_{ref} = 20\mu Pa which is regarded as the smallest sound pressure change the human ear can detect):

    \[ dB = 20log_{10}(P_{exit}/P_{ref}) \]

This is the sound pressure right at the muzzle, which would instantly destroy anyone’s hearing if their ear was right at the muzzle. At a distance of 1m the sound drops considerably

    \[ dB_{1m} = dB_{muzzle} + 20log_{10}(r_{muzzle}/r_{shooter}) \]

We’ll take 3\mu m as the distance at the muzzle and 1m at the shooter to avoid taking the log of zero to get numbers that are typical of rifle report measurements.

Now we are armed to compare recoil between the 6.8 SPC and .243 Win, and for added fun we’ll throw in the .223 Rem and .308 Win to see how they both stack up to a high power round. To get a true apples to apples comparison for recoil, we’ll assume 16″ barrels for internal ballistics. When we look at external ballistics, I’ll leave the 6.8 SPC at 16″ and use the more common 20″ barrel for the .243 Win and .308 Win, and an 18″ barrel for the .223. These barrel lengths will also be used for comparing the report from the rifles. Especially great for comparison, the 6.8 SPC and .243 Win have shoot similar weight projectiles. In this case we’ll compare the 6.8mm 95 grain Barnes TTSX against the .243 95 grain Barnes TSX. Using Quickload with similar near max safe pressures we find the following:

Rifle/Bullet.243 Win 95 gr TSX 20"6.8 SPC 95 gr TTSX 16"6.8 SPC 110 gr AB 16".308 Win 165 gr AB 20".223 Rem 75 gr SMK 18"
Velocity (ft/s)28312707253026302700
Time to Exit (ms)1.080.8020.8771.1650.88
Exit Pressure (psi)16076103909880980911152
F-average (lbf)1160142014061846937.7
Report (dB)144.4140.6140.2139.4141.2

Note that the values for the report in the table are estimates, but useful for relative comparison. Barrel length is representative of typical youth hunting rifle barrels. As the barrel length increases, so does the muzzle velocity, and the report at the shooter decreases as the exit pressure is lower and the point of exit of the bullet is further from the shooter.

As we all know, the recoil from a .223 Rem is very mild and this data agrees. The .308 has significantly more recoil, and the .243 and 6.8 are relatively mild, with the .243 being almost as tame as the .223. From a recoil point of view, either would do but the .243 is best for typical hunting calibers. Muzzle velocity is also the best for a 20″ .243 Win, though the report is the worst of the bunch. Lesson – wear hearing protection when you hunt.

Speaking of hearing protection, a silencer is best, or electronic ear muffs. The 16″ 6.8 combined with a compact silencer makes a great gun, decreases recoil further, and isn’t so long as to be uncomfortable for an American youth to carry in the field. My oldest son has been hunting deer with a 16″ 6.8 AR-15 with an Ops-Inc silencer since he was 11 years old.

In the next post I’ll compare the external ballistics of the 6.8 SPC and .243 Win.

June 2 2017 Range Time

Took 4 rifles to the range on Friday:

18″ 308 Fulcrum

18″ 223 Fulcrum

18″ 6.8 Recon

22″ 6.8 Heavy

Except for the 223, all shooting was with hand loads. Today’s post relays the results of 20 rounds of 308. The rifle was wearing a Vortex PST, decent but nothing fancy.

18″ 308 Fulcrum Results

My version of the 168 SMK FGMM

Load 1:

168 SMK over 42 grains of H4895
Federal cases, CCI large rifle primers
OAL 2.80″
MV 2577fps

Result: 10 shot group at 100 yards

Sigma = 0.249MOA (0.183 to 0.358 – 95% confidence)
Extreme Spread = 0.82 MOA
P1-0.5 = 91.8% (72 to 99% – 95% confidence)
P1-1.0 = 100% (99 to 100% – 95% confidence)

Pretty good. Indicates high probability that 7/10 shots are expected to be within 0.5MOA of true point of aim, and 10/10 shots should be within 1.0MOA of target. For an auto loader this is great.

Load 2:

168 SMK over 43 grains of H4895
Federal cases, CCI large rifle primers
OAL 2.80″
MV 2611fps

Note: First shot was 2″ below the center of the rest of the group. I’m calling this an outlier, but I don’t like it.

Result: 9 shot group at 100 yards

Sigma = 0.389MOA (0.281 to 0.547 – 95% confidence)
Extreme Spread = 1.69 MOA
P1-0.5 = 66.9% (35.2 to 86% – 95% confidence)
P1-1.0 = 97.7% (79.5 to 100% – 95% confidence)

Not as good as the last group, and my shooting ability is an uncertain factor. Still, this data indicates high probability that 3.5/10 shots are expected to be within 0.5MOA of true point of aim, and 8/10 shots should be within 1.0MOA of target. So the question is: did my shooting fall apart and produce this less precise group, did the additional 1 grain of gunpowder cause the degradation, some combination of the two, or something else?

For fun we can combine the two groups by overlaying at the “center of mass” of each group

There is clearly a cluster in the middle and then two outliers. I’ll never know the cause but this is interesting. To get more insight, separating the groups by coloring them differently shows the contribution to the blob above from each (ignore the numbers, they’re for a single group):

The 17 rounds clustered in the middle imply something… the rifle is clearly capable of excellent accuracy for an auto-loading weapon. Did those two shots come from bad shooting? Bad loading? Fatigue? Are they truly representative of the weapon itself?

Possible I wasn’t as careful with the second batch of 10 rounds as I was with the first while charging the cases or seating the bullets. Or I was tired as this was later in the day after shooting the other rifles. And what was with that shot that was 2″ low? Clearly, more range time is warranted.

I’ll get to those other rifles in the next post.

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