Why Do APS Rifles Use More Than Two Scope Rings?
By: Kirby Allen
I have been asked many times about why I use multiple sets of scope rings on many of my APS rifle models. So, I would like to explain this. First let's look at a conventional scope mount system which generally consists of a scope base, most commonly a 1913 picatinny rail, bolted to the rifle receiver then a set of scope rings clamped onto the scope based and finally the scope sits in the scope rings and ring caps clamp the scope solidly into place.
Looking a little more deeply into the details of traditional scope mounting with the systems we generally use on our long-range precision rifles. Let's look at energy control. When we fire a rifle, the action of driving a bullet down the bore of the barrel to high velocities produces a significant amount of energy. This energy is in the form of momentum, as the rifle system is accelerated in a rearward direction, opposite of the direction the bullet is traveling.
This energy is what we call recoil in the shooting world. With a conventional rifle system, this is very simple, bullet accelerates down the bore, rifle moves in an opposite direction into the shooters shoulder, very simple.
As such, mounting a scope on a rifle such as this is also very simple. All you need to control is the g-forces on the scope generated by the rifle acceleration back into the shooters shoulder.
This is simple because it's one dimensional. So, we mount our rail base onto our rifle, mount a set of quality 1913 type Pic rings onto the rail, position those rings forward in the base slot so that the recoil energy is solidly supported by the ring, to base to receiver system, mount our scope and all is good. The scope will stay solidly in this position long term as long as we are using quality rings and bases and the mounting hardware is adequate to sustain the stress of the recoil energy of that rifle.
Simple!!!
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Now let's complicate the matter a bit. We take our favorite long range precision rifle to our local precision minded gunsmith or we purcahse a new rifle that has a threaded muzzle so that we can install a muzzle brake.
A muzzle brake, is a device that uses the escaping muzzle gases that are driving the bullet down the barrel, redirects that gas pressure and volume to DECELERATE the rifles rearward motion back toward the shooters shoulder. This DECELERATION is how we perceive the reduction in felt recoil making such a set up easier to shoot and more comfortable. This DECELERATION is what we in the gun building side of the industry Negative G forces.
Here we find the little issue that can cause dramatic problems mounting a scope and keeping it solidly in place long term. Especially using one of the many great Long Range Precision Optics we have available today that are a bit on the weighty side.
Ya see, the heavier an optic is, the bigger issue negative G forces can be. Again, let me explain. Remember our rifle system that has just fired a bullet down the bore and set the entire rifle system including scope in a rearward movement pattern back towards the shooter.
As the bullet passed though the muzzle brake on our muzzle, our rifle is dramatically DECELERATED by the gases pushing against the muzzle brake parition walls, the heavy scope wants to continue on the path it is on, which means continuing in a rearward direction even though the rifle its bolted onto is slowing down dramatically.
If the Scope rings are mounted in a conventional manner on the rail base, again that being both pushed forward in the rail slot to control recoil energy, eventually, those rings will slip on the rail to some degree.
This may take 5 to 10 shots, this may take 100 shots but there will be slippage. How quickly this happens and to what degree depends largely on three things:
1. The Weight of the scope
2. Intensity of the recoil energy developed by firing the rifle
3. The deceleration rate caused by how effective the muzzle brake design is.
Some muzzle brake designs simply will never have an issue with this as they do not aggressively reduce felt recoil. A radial port muzzle brake rarely has any issues with this, but they also are not very effective at reducing felt recoil.
The more effective a muzzle brake design is at reducing felt recoil, the more extreme the negative G forces are in that rifle system.
My Painkiller muzzle brakes are EXTREMELY effective at reducing felt recoil. By design they are some of the most aggressive muzzle brake designs as I want as much felt recoil reduction as possible.
When I first mounted one of my Large 5 port Painkiller muzzle brakes on my first 338 Allen Magnum chambered XHS rifles, I was amazed at the very low levels of felt recoil. However, after 20 shots through the new rifle i noticed an extreme amount of vertical stringing downrange with my Point of Impacts. Rifle went from legit 1/2 moa class grouping at 1000 yards to 2-3 moa sized groups......
Figured something had come loose so went back in the shop, checked the receiver screws, still tight. Then pulled the scope/rings, checked the base screws, they were all tight still. Remounted the scope and headed back out. Again, shot amazing for 20 or so shots and then again, very noticable vertical stringing.
Thought maybe it was a scope letting loose so switched out the NF NXS for another proven test scope. The new scope had a 34mm main tube so I needed to install a new set of rings. Retested and again, same results, great for 20 shots and then vertical stringing.
About at my wits end I decided the issue was likely the rail base slipping on the BAT receiver, so I machined the rail and receiver so that 4 heat treated steel 1/8" diameter pins were holding the rail base solidly in place, impossible to slip now.
Reassembled the rifle and headed back to the range. To my horror, the situation got even worse, now only 10-12 shots were good before seeing vertrical stringing......
Now, looking back into my memory to my big bore handgun hunting days, I remembered mounting multi ring set ups on severe recoiling handguns mainly to protect the optics used on those handguns.
I had an extra set of Nightforce 30 mm Ultralight Tactical rings on the bench, so I remounted the NF NXS scope with two rings ahead of the scope turret and two behind the turret. Headed back out to the range. This time, I put 25 rounds through the rifle and had no change in POI at all, very excited and promising.
Loaded up a batch of more ammo that night, cleaned the rifle and headed back out the next morning. Put 25 more rounds through the rifle with great results but then between shots 50-60 with this scope mounting I started again to see vertical stringing. Not as severe as before but noticable, around 1.5-2 moa.
Progress though!!
Headed back to the shop and just set there pondering this issue. I could not sell these rifles until I solved this issue. Then it dawned on me, it was possibly the negative G forces generated by the muzzle brake. So, to test this theory, if you numbered the mounted rings 1, 2, 3 and 4 starting with the ring closest to the barrel, I positioned rings 1 and 3 forward in the rail slot to control the recoil energy produced by this massive 338. Rings 2 and 4 I positioned to the rear of their base slots which should control the extreme negative G forces generated by the muzzle brake.
Headed back out to the range and shot 50 rounds and not a single issue with POI. Over the next week I had four range sessions where I shot at least 50 rounds of ammo and again, not a single noticable shift in POI......
I continued to test this mounting system for a couple months, putting many hundreds of rounds down the bore, easily using up 1/2 of the accuracy life of this barrel but R&D is rarely cheap. It was clear that I had figured out how to prevent any scope ring to rail slippage and solved this problem.
However, was this needed for every rifle using my PK brakes or similar designed brakes or was there a certain point where it was not needed, depending on chambering size and weight of optical system.
So the testing continued, next was one of my old Xtreme Sporters chamebred in my 338 Allen Xpress, basically my improved version of the 338 Lapua. This rifle design would become what I sell today as my Stalker Hunter rifle model. Pretty intensive negative G force load produced by my small PK brake.
Ran the same test as I had with the big XHS using conventionally mounted heavy scope and sure enough, vertical stringing again. This time however I mounted two rings ahead of the scope turret bult only one ring behind the turret for a total of three rings instead of four. On the front two rings, one was positioned forward on the rail, one rearward. The single ring behind the turret was positioned forward for recoil energy control. This mounting system stopped all vertical stringing.
Next up I did the same test on a 6.5-284 varmint rifle. Conventionally mounting the scope showed no vertical stringing of any kind for several hundred rounds so it was clear that multi ring mounting systems were not needed for this class of rifle.
Tested several other rifles of varying intensity and came to a shop policy recommendation conclusion.
On my Raptor LRSS rifles, I recommend using a 4-ring mounting system on all chamebrings using the Lapua class sized case. Smaller case chamberings could get away with using only two scope rings but even with these, I now decided to mount one ring forward for recoil energy control and one ring to the rear for negative G force energy control.
On my Stalker and now Prowler rifle models, I recommend a 3-ring mounting system on all magnum chamberings when using a scope weighing over 25 ounces. Standard chamberings or when using a lightweight scope can get away with using 2 rings but still mounted as I discribed on my Raptor rifles.
On my XHS rifles, it's recommended to use a 4-ring mounting system on all of these rifles since they are all chambered in my Cheytac based wildcats, very large, very high intensity chamberings.
In the end, it may well be overkill in many situations. But for many other applications that I deal with all the time, it has been proven to be a nessesity to use a multi set ring scope mounting system to keep heavy scopes mounted rock solid for very long-term use.
And in the end, its relatively low-cost insurance to make sure your scope does stay rock solid longterm.
I have been asked many times if the one-piece scope mounting systems are better and to be blunt, they are usually worse as there is no way to seperate and support both the recoil energy and the negative G force energy. As such, I rarely recommending using a one piece scope mounting system.
While many over the years have made comments about my use of more than 2 scope rings, in my testing with my wildcats and with my Painkiller muzzle brakes, for many applications, it is absolutely a necessity to ensure that a heavy scope will stay rock solid long term. It's not just for looks, it's not just an excuse to spend more of my customers money on scope rings.
There is a very real reason why I recommend it and with each application, I will tell my customers which mounting system I know will serve them best long term.
How The Allen Magnums Were Born
By: Kirby Allen
I have been asked many times over the years, what got you into designing wildcat cartridges? Honestly it is a rather interesting story that started back around 2005.
At this time my shop had been up and running for a few years and I had just started offering semi-custom, built rifles for sale to customers. The very first two chambering reamers I purchased for my new shop were for the 6.5-06 Ackley Improved and then for the 257 Shooting Times Westener. In the picture to the right, you can see the very first 257 STW that my wife Becky used to take a great Montana Pronghorn. Worked amazingly well.
From that first 257 STW I went on to build many dozens more of these rifles based on fully blueprinted Remington 700 receivers. I started to get a bit of a reputation for building good rifles in this super 1/4" bore chambering.
This went on for a couple years and then one day while I was in a local sporting goods store, I overheard a couple guys talking about how this new young gunsmith had STOLEN the design of an older well established gun builder and saying that he was claiming it was his design. Hearing this I asked the two men what the story was all about, and they shared a conversation they had had with this other gun builder, and he was saying that this new whelp had stolen his wildcat design and claimed it for his own. I asked them the name of the young smith and to my amazement they said Kirby Allen.
Becky Allen with her first Montana Pronghorn
I literally laughed out loud when I heard my name come out of their mouth. Told them who I was and then explained how the Stolen wildcat the other builder was referring to as his design was the 257 STW which gun writer Layne Simpson had designed about 5 minutes after he designed the 7mm STW......
I walked away from the conversation with a big smile on my face thinking how silly it was. However, over the next few months, I heard this story repeated by several other local shooters and it really started to bother me as I had never STOLEN any design from anyone and never would.
I knew I did not need a reputation, legit or not, of being someone that was taking someone elses design. It was obvious this other builder had access to many more people in the business then I did at that time. So, I decided I would put an end to these conversations. If people wanted to talk about me and my new little shop, I was going to give them something to talk about.
Set down and started drawing up a reamer print for a new wildcat that would blow the doors off of the SUPPOSEDLY STOLEN 257 STW design. After playing with several different parent case choices, I decided the 338 RUM was a good choice.
The 338 RUM had a slightly shorter case length then the 7mm or 300 RUM which would bring its capacity down a bit. Still very large capacity for this caliber but I was looking for the ultimate wildcat design.
I also decided that I wanted to sharpen the shoulder angle some but knew I did not want a full 40-degree angle. Liked the idea of the 38-degree shoulder angle which to this day is the shoulder angle for all my wildcats. I also designed my case body taper design with a good amount of taper to allow proper extraction performance at top end chamber pressure ranges.
It was also at this time that I met my good friend Richard Graves, who owned Wildcat Bullets in Alberta, Canada. He made an extensive line of custom bullets for many different calibers. We talked about my wildcat design and some of his bullet designs. He said he would send me some bonded core 100 and 130 gr high BC hollow point, flat base bullets. He also said he would include a surprise in the shipment.
When it arrived, I found the 100 and 130 gr HP bonded core FB bullets which looked very good. There was also a couple boxes of bullets labeled 156 gr ULD RBBT. I had to check these out and when I opened them, I saw a 257 cal bullet like I had never seen before. I had mentioned to Richard that I wanted to blow the doors off the 257 STW and do something that had never been done before. Seeing these amazing projectiles, I called up Lilja and instantly ordered a 1-8 twist barrel.
Everything needed to build the test rifle showed up and it was time to put the first bullets in the air.
This other smith that was claiming I had STOLEN his design claimed that his 257 STW wildcat would produce 4000 fps with a 100 gr. bullet weight in a 28" barrel. Something I quickly learn from building and doing load development for many of these rifles, was not even close to reality, infact, in a 28" barrel, 3800 fps was about maximum if you wanted more than one firing per case.
Even in a full 30" barrel length the 257 STW was limited to around 3900 fps. This was my target goal. If my wildcat was to overshadow HIS design, I needed to top this level of performance by a signifcant amount so there could be no more CLAIMS of STOLEN designs. However, I now realized that there may be much more to be had then just a hyper-velocity speed demon. My test rifle was based on a Remington 700 chrome moly receiver with a 30" Lilja 1-8 twist barrel. I decided to start with the 100 gr Bonded Core HP bullets to help learn the Personality of the new wildcat cartridge and rifle. Using heavy doses of ultra slow burning military surplus powders like WC-872 and WC-860, it became instantly clear that breaking 4000 fps would be quite simple. In fact, top loads produced right at 4100 fps while offering a minimum of 4-5 firings per case.
Left to Right: 6.5 wsm, 264 Win Mag, 257 STW, 257 Allen Magnum, 338 RUM
This was my goal as far as case life using the remington brand brass which was not known for being overly strong brass. The 130 gr BCHP, which at that time was a MONSTER sized bullet for the 257 caliber clocked a sizzling 3575 fps, producing a power level much closer to larger 7mm magnums on the market then any 257 caliber magnum. Finally, it was time to develope the load for the huge 156 gr ULD RBBT. I was very happy to see these bullets clocking 3450 fps.
While this looked great, it was not until I took this combo to my long range shooting area and did some bullet drop testing that I really understood just what I was working with. The BC measured off actual bullet drop testing over a full 1000 yards proved to be 0.880 on the G1 scale. Back then very few used the G7 model for BC. Nearly 4200 ft/lbs of muzzle energy!!! With a 300 yard zero, only needed 12.0 moa to be dead on at a full 1000 yards.
At this range the big 156 gr ULD RBBT was still clipping along at 2600 fps with over 2300 ft/lbs of energy.
Comparing these numbers at long range to the specs of the STOLEN 257 STW 100 gr load, even giving it the falsely advertised 4000 fps velocity, same 300 yard zero, at 1000 yards the STW it needed 13.5 moa of dial up, not bad but still 1.5moa more then my 257 Allen Magnum. Biggest difference, the STW load only had 1900 fps retained velocity and only 820 ft/lbs of energy. There was no comparision of any kind.
It was at this early stage of my wildcat career that I realized speed was great, but speed with long, heavy, high BC bullets was where the magic was at. This was the moment my motto of Faster, Flatter and Farther then ever before started. No other 257 caliber cartridge had EVER come close to producing these performance and ballistic numbers.
That was the start of the Allen Magnum family of wildcats. Soon after that would come the 6.5mm Allen Magnum and 270 Allen Magnum. Then one of the most popular of all my wildcat designs, the 7mm Allen Magnum which was my first attempt at stepping up to the extremely strong 338 Lapua parent case. This took my wildcat Families to entire new levels of performance.
All of these with the partnership of my great friend to this day Richard Graves making me bullet designs specifically for my wildcat designs to bring out the full potential. While Wildcat Bullet company no longer is in business, I will forever be in debt to my good friend for helping me get where I am today.
In the end, the birth of my APS wildcats was simply because of an old local gun builder spreading lies about me and I decided to put an end to it nearly as quickly as it began. From that time, nearly 23 years ago, there have been no false stories coming from that old gun builder. There has never been another comparision worth mentioning. What a ride it's been!!