Why recoil “contraptions” don’t, or can’t, tell the truth.

Why recoil “contraptions” don’t, or can’t, tell the truth.

 

We get asked a lot, “What percentage reduction does your brake provide?”, but it’s not an easy question to answer in percentages. The reason is that “felt” recoil is a very subjective quantity, and measuring “feel” is like measuring “taste”, because it’s not the same for everyone.

Now. There are numerous methods of “testing” recoil and reduction thereof, but translating those measurements into “felt” recoil reduction is not a very easy task. I’m going to run down the list of a few different methods people use to measure recoil and recoil reduction, explaining the failings of each. This is not to discredit anyone for their effort(except maybe one, whom I’ve attempted to explain to him where he went wrong so that he could re-evaluate his results instead of committing journalistic malpractice) , It’s merely to point out why it doesn’t tell the whole story.

 

  1. Free Recoil method (no sled) measuring distance traveled. Believe it or not, this is probably the most accurate comparison to “felt” recoil, and obviously the most low-tech. It still isn’t perfect because it is only measuring the distance traveled with no resistance. Resistance is an important part of the equation because your shoulder will provide resistance even without being noticeable or uncomfortable, whereas free recoil provides little or none. This goes back to some things learned in the barrel length article, such as recoil velocity is more important than recoil distance only when you reach a certain amount of travel. i.e. A rifle that’s recoiling 10fps at 4” and stops by 6” with brake (a), will have more “felt” recoil than the same rifle that’s recoiling 10fps at 2”, 5fps at 5”, and is still moving 2fps at 8” with brake (b), even though brake (b) traveled farther. (for perspective a 7lb 223 running 55s at 3000fps = 6.2fps recoil speed)
  2. Free Recoil (with sled) measuring distance traveled. This method actually skews the results even farther because you are adding mass, and probably friction, to the equation. Not useful for comparing brakes or assigning percentages, but is a good illustrator of brake vs no brake.
  3. Load sensors with a “mostly” zero, or zero travel setup. I guess the best place to start on this one is by drawing attention to an article that many have read, and a lot taken as gospel, even though his own data shows that he basically measured everything BUT how well the brakes worked (if you have doubts about this run QL or look into how many milliseconds it takes for a bullet to exit the barrel, and compare it to his graph. At .006ms he’s comparing peaks when the bullet isn’t even halfway down the barrel, brakes aren’t doing anything at that point). In fact his video on his test setup shows that what I was telling him was fact( I explained to him that he was measuring the loading of the sensor and frame to the first plateau, and the second plateau showing peak thrust with all preload removed. The rifle then proceeds to launch forward 4”+ as the frame/buttpad/stirrup unload). In the prior article ( https://kahntrol.com/the-effect-of-barrel-length-on-recoil/ ) I explained how a muzzle brake can do exactly NOTHING until the bullet exits the muzzle, and peak recoil occurs while the bullet is accelerating inside the barrel, so using a static load sensor and a no travel set-up, you are only actually going to measure the recoil that a brake can’t stop. (on a side note about the tests performed by the other author, Had he used a bungee, strap, or other method, and actually preloaded the sensor, his readings would have been virtually identical between the different brakes. When you’re dealing with forces that are generated in less than a quarter of an inch, with tremendous acceleration rates, a difference in .010” of preload travel will show huge differences in readings. Also the load sensor in question requires a precision ground(within .0005”TIR) mounting surface and an absolute linear load-path to even think about being accurate. )

 

Before I go any further, I want to state for the record that I have no ill will towards the author mentioned above (I hear he’s a good guy), and I had no dog in the fight for his testing, but I did attempt to explain to him, how and why, his data was flawed before he published the last 6 articles of his testing, but he carried on nonetheless. I honestly felt bad for him after all the time and effort he spent, but passing off flawed data as scientific results should NOT be excused just because you expended time, effort, and money.

 

Is there a scientifically accurate way to measure felt recoil, or the reduction thereof ? Yes. Here’s what would be required:

  1. A chassis type rifle with a collapsible AR style buttstock with the locking pin removed and a load sensor and spacers “properly” installed within the stock between the butt plate and buffer tube, ensuring proper LOP for the shooter.
  2. A break-wire or similar system at the muzzle to log the precise bullet exit moment.
  3. An objective but experienced shooter to pull the trigger, is consistent with shoulder preload, and not run away from the recoil (skewing results).

Using this method would allow you to isolate the recoil forces that occur only after the bullet has exited the barrel, giving you an accurate dataset to compare brakes and also non-braked rifles. In addition you should be able to calculate the resistance and range of travel offered by the shooter in order to devise a mechanical resistance apparatus to simulate the rifle being shouldered without risk of human error to cloud results.

 

So. When people ask “How much reduction can I expect?”, you may not get an answer in percentages, but I can tell you pretty darn accurately what the recoil’s going to be comparable to. And, in 6+ years, no ones accused me of being wrong in my predicting their results.

 

Safe-Pressure work-up data for upcoming BBTI(ballistics by the inch) focusing on heavier than standard 308win bullets.

These loads are non-standard loads and SHOULD NOT be considered safe in any rifle other than the rifle they were developed for!!!

In the upcoming weeks, we will be performing a pretty exhaustive bbti study looking at not only standard 308win bullets(there are several out there already with standard weight bullets), but also heavier than standard weight bullets. Even though we have loads developed for a 20” 308, we figured it best to start from scratch on developing the heavy bullet loads for this rifle (26” rem700sps-v, with a 10k+ rds factory 12twist barrel). This rifle has a loooong factory chamber and will accept loads beyond the 2.960” that an aics mag will accept. With my comparator, the throat of this rifle requires 2.470” base to ogive to touch the lands with a Berger 185 juggernaut, which because of ogive shape is .010” longer than Hornady 168bthps require (for reference, this means that a 185jug has to be loaded to a .070” longer coal than the referenced 168, to achieve the same base to ogive measurement). With the mag length and BTO measurements taken into consideration, I decided that No load would exceed either 2.950” coal or 2.470” BTO for the purposes of function and safety in this rifle.

I will also note, these loads are not accuracy loads, and with the 12 twist barrel they are not stable with 225gn Hornady bthps or the 230gn Berger hybrid OTMs, but this study is going to be about velocity changes with barrel length changes. These loads are merely to establish SAFE loads in this rifle.

The data listed below is bullet, brass, primer, coal, BTO measurement, powder charge(of CFE223), and shot velocity. 208s and 210s were 2rds per charge over 5 different charge wts, the 225s and 230s were single shot per charge for 10 different charge wts, primarily because we started very low on the bullets that data didn’t exist for, and we had limited matching lot brass for pressure loads and for loading the BBTI loads. I will note here that NONE of the loads tested showed any signs of pressure in this rifle with these loadings. Also, all brass was fireformed in this rifle and then sized with a Redding body die with a +.006” competition shellholder, and necksized with a Lee collet necksizing die. Velocity data was recorded with a magnetspeed sporter.

The DATA:
208amax, LC-11, WLR, 2.950”coal, 2.213”bto
1. 42.5, 2419
2. 42.5, 2409
3. 43.0, 2441
4. 43.0, 2417
5. 43.5, 2468
6. 43.5, 2459
7. 44.0, 2507
8. 44.0, 2492
9. 44.5, 2523
10. 44.5, 2515

210vld match, LC-11, cci34, 2.950”coal, 2.277”bto
1. 42.5, 2312
2. 42.5, 2318
3. 43.0, 2342
4. 43.0, 2356
5. 43.5, 2375
6. 43.5, 2365
7. 44.0, 2422
8. 44.0, 2424
9. 44.5, 2453
10. 44.5, 2455

225bthp Hornady, Win, cci34, 2.950”coal, 2.290”bto
1. 36.5, 1967
2. 37.0, 1960
3. 37.5, 1984
4. 38.0, 2054
5. 38.5, 1982
6. 39.0, 2100
7. 39.5, 2126
8. 40.0, 2086
9. 40.5, 2140
10. 41.0, 2280

230hybrid OTM, LC-11, cci34, 2.950”coal, 2.255”bto
1. 36.5, 1949
2. 37.0, 2051
3. 37.5, 2060
4. 38.0, 2085
5. 38.5, 2063
6. 39.0, 2089
7. 39.5, 2177
8. 40.0, 2176
9. 40.5, 2231
10. 41.0, 2259

Some take-aways; I should’ve prepped more brass so that I could’ve worked up a little hotter. When I say there were no pressure signs, I mean NONE, bolt lift was on par with my sub-sonic 155amax trailboss loads, as in lighter than factory ammo. Most of the velocities attained are pretty close to the Berger Reloading manual Max velocities, but without the associated pressures due to longer than saami loading, but it does show that with the proper chamber dimensions and a longer mag, the potential is there for decent velocities with heavyweight 308 bullets. I will also say that even with the 208s/210s, the report was very modest, which means that bore pressures had dropped significantly by the time the bullet exited which means that the bullet was probably not accelerating and possibly “coasting” before exiting, but that is what we’re going to find out with the BBTI, because when case volume is limited by bullet length, and burn rate is limited by bullet weight, It’s not a stretch to think, that when you limit volume against a known max pressure, you may have too much barrel for your bullet.

 update 09-14-16, had a few extra pieces of brass for the 208 loads and the 230 loads, loaded up a few more steps because I feel like the previous were a little on the light side. will run them tomorrow and then start loading the heavies for the BBTI.

The effect of barrel length on recoil.

The effect of barrel length on felt recoil:

One of the often overlooked aspects of recoil, and recoil forces, Is how much the barrel length can affect the felt, or perceived, recoil of a given firearm.
Everyone understands (I hope) that recoil is merely a force that is created by an explosion (deflagration if you want to be technical) with a bullet on one side going one direction and the firearm on the opposing side going the other direction. This force can be can be calculated with a relatively high rate of precision and applied to both actions(bullet acceleration and rifle acceleration), but I’m not going to bore you with a math class, but if you want to geek out and run the numbers on your own, the calculations are relatively easy to find. Now that we understand what starts the recoil process, we can move on to the rest of the story. The rifle, and bullet, are going to accelerate in opposing directions (but at much different rates, unless the rifle and bullet have the same weight) until either the expanding gases are released, or friction inside the barrel overrides the ability of the expanded/expanding gases to maintain acceleration, but either way, once the gases are no longer playing a part, it’s just a matter of momentum. One thing to note when you play with the various recoil calculators that are available, they don’t ask about barrel length because if all other variables remain constant, the recoil velocity will not change.
Now, to illustrate how the above information relates and brings barrel length into the equation, I’ll give a couple of examples:

a) a 12lb 308 with a 26” barrel, shooting 168s over 44.5gns of Varget. QuickLOAD predicts 2736fps, and plugging this info into a recoil calculator gives a recoil velocity of 8.12fps and using a ballpark 10ms as the barrel dwell time we get .9744” of travel under power (8.12*.01*12=.9744”)

b) same 12lb 308 with a 20” barrel shooting 168s over 44.5gns of Varget. QuickLOAD predicts 2592fps and the recoil calculator gives a recoil velocity of 7.83fps and the change in dwell time goes from 10ms to 7.692ms we now get .7227” of travel under power, in addition to the lower velocity.

c) This time it’s a 12lb 30-06 with a 20” barrel shooting 168s over 49.5gns of Varget to achieve 2736fps(to put our velocity back to what our 26” 308 could attain). And now plug this info into the recoil calculator and we get a recoil velocity of 8.42fps and with the reduced dwell time we see the recoil distance go to .777” of travel under power

So, as you can see, Keeping the rifle weight and bullet weight the same, and only changing the barrel length, you end up with a reduction of 26% driven recoil distance, and reduction of 6% of your velocity. BUT, you can go to a slightly larger capacity case (308 to 30-06) with the shorter barrel and maintain your bullet velocity while still reducing your driven recoil distance by 13% . One thing you will need to keep in mind, is that once you reach a certain point (which varies depending on the shooter, but is typically in the 7.5-8.5fps range) recoil velocity matters more than recoil distance (typically regardless of recoil velocity it takes more than about 1.5” of driven recoil to become uncomfortable) on a non-braked rifle, because the velocity/mass will continue rearward until your shoulder acts to stop it.

In conclusion, this information pertains mainly to like for like comparisons of recoil and is a based on a non-braked rifle. The calculations can also be applied across calibers to compare if you can achieve similar or better ballistics without increasing recoil. This, still, is important, even if you run a brake that sufficiently arrests the rearward momentum of the rifle, because the driven recoil distance/speed is what the rifle does before a brake can actually start working. Many of you may have no interest in the above info, but for those of you contemplating a rifle build with a particular set of parameters, you may be surprised at the options that open up when you start playing with recoil velocities, barrel dwell time, bullet weights/BCs, and bullet velocities, while still maintaining your goals for wind drift, drop, and rifle maneuverability. Sometimes its better to swing a short handled heavy hammer, than a long handled light one.

 

Installation video for the PodMod Adapter System

For those that have wondered just how hard is it to install the PodMod Adapter system here you go. And before you go saying “but you have installed alot of them” you are mistaken, this one makes a grand total of 4 adapters (not 4 pairs but 4 adapters). With that being said someone taking their time could still easily install a pair in under 10 minutes. Of course with our TacPac systems we do the work for you. Find out more here.

Excellent Article from Accurateshooter.com concerning barrel threading

Though this article is recent, and not our inspiration for choosing the primary thread pitch on our HexMod brakes, it does illustrate our reasoning behind it.

If you are planning on threading your barrel, or are ordering a custom barrel pre-threaded, please read the referenced article.

http://bulletin.accurateshooter.com/2015/04/muzzle-threading-dont-remove-too-much-steel/

Where we’re going!!!

Though we are known for our World-Class Effective Muzzle Brakes, We are constantly looking to find or create innovative products, ideas, and solutions to make shooting experiences better and more efficient.

As we go down this path we will be posting “how-to’s” on methods we’ve found to make things easier, like our reticle leveling method or our posts to improve understanding of how’s and why’s of shooting and guns, Like our scientific explanations of Brakes vs. compensators, or recoil mitigation science.

We are also going to be adding products that, first and foremost, are practical. Some items may have inherent “cool factor”, but that is secondary. Some products may be of our own design, some may be proven performers manufactured by others, but they all will based on practicality. Whether it’s our PodMod Adapters, B&T industries’ SILO devices and bipods, or the whatchamadoodlethingomabob by the hermit under the hill, If it’s on our site, IT WORKS and it’s PRACTICAL!!!

So, keep your eyes peeled and watch for new posts and products by liking us on facebook and don’t be afraid to send us a contact form about your projects with our products, or input on things you’d like to see on our site, from products or how-to’s, to information and explanations.

Keep it tight and on target,

Jeremy Kahn and the Kahntrol Solutions Team

 

 

Leveling a reticle

You are always hearing of different ways to level a reticle in a scope, from hanging a plumb line and looking through the scope, to fancy level systems that can cost a fair price. The problems with these methods can vary as well, with the plumb line method trying to hold the rifle level, look through the scope and twist the scope all at the same time can be difficult. Or as Caleb D. on facebook found using one of the leveling systems his turret would give different level readings depending on where it was dialed to.

Well here is a new way of doing it that I shared with Caleb and he was more than happy to take a few pictures to help with the tutorial.

Start by hanging a piece of white poster board up with a plumb line hanging in front of it, the finer the plumb line the better..

Set the rifle in a cleaning rest or on bipods with the buttstock next to the plumb line but not touching it.

Now use a level to get the rifle as level as possible.

Now find the absolutely brightest light you can and shine it into the objective of the scope, focus the scope until you have a nice clear projected image on the poster board.

Now you have a clear view of what adjustments you need to make and both hands free to make them.

Other reasons this is our preferred method are due to Jeremy’s background as a machinist. Despite every best effort of the manufacturers there are allowable tolerances in anything that is made in this world, i.e. your rail may be .001 out of level, the reticle lens may be slightly twisted in the tube, the tube may be slightly misshaped. All of these things are possible and it basically comes down to.. If your goal is to level the reticle, level the reticle rather than the tube or other parts around it that could be slightly off.

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Green Beret Foundation Pro-Am

We recently had the opportunity to be a small part in the Green Beret Foundation Pro-Am by way of donating some of our 3-Gun brakes for prizes and auction items. Be sure and check out the great work this organization does for our Green Beret Forces! While we were there we noticed that one of the rifles being used in a stage was wearing one of the 3-Gun brakes the owner of the range recently purchased from us. We were able to get some video of our brake being used on a rifle side by side with one that wasn’t (ours is on the rifle closest as the video begins). If you watch the video you will clearly see the reduced recoil as well as how quickly the shooter is able fire followup shots. The rifle barely moves on double-taps.

Also, the 4th place team were presented a pair of Kahntrol Solutions 3-Gun Brakes.

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My morning at BangSteel!

bangsteel

Yesterday morning(9-19-2014) I drove to Wytheville, Va, to visit Dan and the folks at BangSteel.com Practical Long Range Shooting School, and to Deliver a couple of brakes to the gentleman who owns the land where BangSteel operates. Upon Arriving, there was a class of 6 getting their baseline zeros dialed in, and a few having trouble seeing the splash on hits and misses due to recoil (Dan is a firm believer of needing to spot your own shots). So, Dan explained to the class who I was, and asked if I had brakes that the classmembers could try out. And Me, who while on the road drives a rolling warehouse, said “Sure”, and preceded to snatch my rifle(a Remington 700 varmint in .308) out of the back seat.
After setting it down on the shooting mat, I gave them a choice of firing my rifle with either my loads(175smk@2750fps) or theirs, or I’d install a brake on their rifle and let them test fire it. One gentleman with a 6.5grendel AR opted to try one on his and was amazed that not only could he watch his hits, but was also able to attack the targets with a higher rate of fire. Needless to say, I didn’t have to take his brake off!
The rest elected to fire my rifle and after feeling the lack of recoil, they would give the evil grin that signified “I Gotta Get One Of These”!
So for the next 30 minutes I fitted brakes onto the rifles of the entire class and answered questions about which sizes they’d need for their other rifles, torque specs, and general questions about why they work so well compared to other brakes.
In the end everyone was excited about how much easier it was to “reach out” and how much confidence and concentration is gained by not having to reacquire targets and position during a string of fire.
I’d like to Thank Dan and the entire staff at Bangsteel for having me up, and for the work they do, teaching people that even with a hunting rifle and half decent glass, you Can reach out to 1000+yds!
If you get a chance, check them out at www.bangsteel.com

Muzzle Brakes vs. Compensators

Among many people there is a misconception that muzzle brakes and compensators are the same thing. This could hardly be further from the truth.

Firearm recoil is a combination of three different forces;

1. Newtons 3rd law, When the bullet starts moving it forces the firearm to start moving in the opposite direction, this force only last milliseconds.

2. Thrust, When the bullet leaves the muzzle the escaping gases provide thrust which allows the rearward motion of the firearm to continue.

3. Axial rotation, Except in rare instances, the barrel of a firearm is above the center of gravity of the firearm and any forces acting on the barrel are going to induce rotation around the center of gravity (commonly refered to as muzzle flip).

A muzzle brake is designed to arrest the rearward momentum created by the first 2 forces and in turn prevent the 3rd alltogether. The first force CANNOT be stopped, but it’s over so fast that without the thrust from #2 to continue the motion, the firearm would hardly move at all. However, the 2nd force, thrust, can be “caught” by the muzzle brake, which basically acts like a parachute catching the escaping gases. These gases are moving roughly 3-5 times the speed of the bullet and even though we think of gases as not weighing anything, they in fact do have weight/mass, and since energy is mass times velocity squared, even the minute weight/mass of the gases impact the brake with enough force/energy to stop the rearward momentum almost entirely.

A Compensator, Such as the ones you see on AR style rifles and competition pistols, are ONLY designed to mitigate #3, rotation or flip. They accomplish this, not by catching the gases, but by redirecting them to create thrust in the direction opposite the rotation imparted by the first 2 forces.

Even though Compensators may reduce recoil slightly, their purpose is to control flip or muzzle rise. In finishing, A Compensator is like a steering wheel, it “steers” the recoil. A Muzzle Brake is like, well, a brake, It Stops the recoil.

And please don’t call them Muzzle Breaks !!!