Giving the ACSS Vulcan Dot on the Holosun 507K a Fair Shake

I was on the fence about the Primary Arms ACSS Vulcan Dot reticle on the Holosun 507K after my initial review. So I decided to do some work with it to determine whether or not it was worth the additional $30. I found that it is and this post explains why.

Earlier this month, I published a very brief review of the Holosun 507K with the ACSS Vulcan Dot. In that review, which focused primarily on the reticle, I mentioned that the reticle design, which I’m very fond of, provides a “crutch” that aids in fast aiming corrections. While I wasn’t overjoyed with the size of the center dot as the aiming reference, I intended on giving it a fair shake and see if it would dethrone the standard “doughnut of death” reticle of the Holosun 507K as my favorite reticle like the ACSS Vulcan reticle did on the Holosun 507C. As such, I performed a couple of unscientific experiments with the 507K to help evolve my opinion and that’s what this post will cover.

Let us begin with a little context. I’ve quoted the term “crutch” on purpose. The “crutch” I am referring to is the 230 MOA dashed outer ring that encircles the 3 MOA center dot which together make up the entire ACSS Vulcan dot. The purpose of the outer ring is to provide the user of the optic with an aiming correction reference which should facilitate in finding the dot when the dot is outside the frame of the optic. This is a problem that occurs when the pistol is improperly aligned with the target. The problem is quite common among less experienced shooters who don’t have a well developed aiming index or pistol presentation. The frequency of this problem diminishes as experience and skill increase, but even experienced shooters can encounter the problem due to human error which can be exacerbated by stress and other environmental conditions.

The vast majority of this reticle design detractors, which are few in number, I’ve come across argue that the crutch is invites laziness and worry that users won’t be incentivized to do the work required to develop a good pistol presentation technique since the “crutch” makes finding the dot easier. I disagree with this position. There is no “easy button” to becoming a highly skilled marksman. Skill is not something that can be achieved by purchasing gear. However, advances in firearm technology can accelerate the pace at which one can acquire those skills and raise the level of marksmanship that is possible at the peak of human performance. There is plenty of evidence to support this that can be found in academic research, but is glaringly obvious when one compares score differences among the different divisions in competitive shooting. This might appear a bit tangential on the surface, but I believe it supports the notion that gear or rather advances in technology and even “crutches” doesn’t invite laziness and may even fuel motivation for skill development. Regardless, I’m less interested about the motivational, or de-motivational depending on one’s position, aspects of the reticle’s design than I am about the other potential benefits I see from it.

What benefits? That is the question. Admittedly, some of the benefits I see are speculative. However, they are all based on the reticle design premise which is: the reticle design virtually eliminates the need to “fish for the dot”. “Fishing” for the dot is essentially the circular movement of the pistol’s alignment made by most folks when attempting to find a dot that is not visible in the frame of the optic’s lens. The current corrective technique to eliminate “fishing” is to use the back up sights as the aiming system when the dot is not visible. This technique works, but it is a skill that requires development. Furthermore, the ACSS Vulcan design does not eliminate the need to develop this technique as it may still be needed if the optic with this reticle has suffered a power failure. However assuming the optic is functional and powered on, the ACSS reticle should significantly reduce the need to employ the “shoot-the-sights” technique given its design should facilitate rapid aiming correction. I’ll introduce and cover the speculated potential benefits as this post progresses, but for now let’s return to the foundational premise – the virtual elimination of “fishing”.

The best way I could think of putting the premise to the test was to slap the 507K on a pistol I wasn’t intimately familiar with and put it to use. Yes, that is completely unscientific and my findings are purely anecdotal. However, that is the best I could come up with and frankly I didn’t really have a choice since I didn’t have a fast and easy way to mount the 507K to any of the pistols that get regular trigger time.

The pistol selected for this endeavor was the Sig Sauer P365 XL. To be honest, the primary factor is that it is the only pistol I had available that I could mount the 507K on to. Nevertheless, it served the purpose as the P365 XL doesn’t get much trigger time. This might surprise readers who are well aware that the P365 XL is my favorite slimline defensive carry pistol. To put things into context, I seldomly carry the P365 XL. It also gets virtually no dry fire practice time. While I did put 500 rounds through it in the past twelve months and that may sound like a lot to some folks, it is an order of magnitude less than the rounds that went through the VP9 last year and about the same number of rounds that went through the Shadow 2 in the last month. So while I have some familiarity with the P365 XL, I am far less familiar with it than I am with the other pistols I just mentioned. Moreover, this means errors in grip and technique are more likely which, in turn, increases the likelihood that I will rely on the 230 MOA dashed ring for corrections.

Results from a 10-10-10 drill with the P365 XL / 507K ACSS combo

The optic trials began with a short trip to the local indoor range, which is open to the public, where I ran a few timed drills. As is typical of all the public ranges I have nearby, drawing from the holster is not allowed. In lieu of drawing from the holster for drills that start in the holster, I started with the gun on the bench to simulate a nightstand pick up. It’s not a perfect substitute, but it does force one to establish a grip and present the pistol as part of the drills.

Aside from noticing that I was shooting low and left with the P365 XL, there were a couple things I noticed during the range session with regards to the ACSS Vulcan Dot reticle. The first thing I noticed was that I was able to pick up the top edge of the 230 MOA dashed ring with my peripheral vision during the presentation of the pistol significantly earlier than I would normally pick up the “doughnut of death” reticle found on the standard 507K. This allowed me to smoothly adjust each pistol presentation naturally so that at full extension the center dot was consistently present. In my opinion this is a pretty big benefit and I found myself having very consistent and fast presentations as I warmed up. 

Another thing I noted was that I really wanted a larger aiming reference. The 3 MOA center dot requires more visual attention than a larger dot, the “doughnut of death”, or the 10 MOA chevron (found on the ACSS Vulcan Reticle that is available on the 507C) does. That said, I’m no longer certain that a larger aiming reference on an optic of this size would result in dramatically different results especially given they are mostly likely going to be mounted on smaller slimline pistols. My rationale for this begins with the fact that these smaller pistols tend to have a snappier recoil profile than larger duty sized pistols. That recoil profile generally translates into more muzzle flip which in combination with a small optic lens and frame means the aiming reference, regardless of its size, is going to be out of frame during recoil unless one has the ability to grip that pistol in a vice-like manner. This recoil recipe basically puts tracking the dot during recoil on hard mode. Furthermore, smaller pistols tend to be less forgiving to trigger manipulation and grip which translates into requiring more careful attentiveness to mechanical technique.

In other words, I would still like to see a larger aiming reference on this optic, but I can live without it because I found an additional benefit from the 230 MOA dashed ring during recoil that I hadn’t previously considered. That benefit is that the dashed ring provides valuable feedback as to what the gun is doing under recoil that is similar to what one would get if they were able to track the dot. I know I just said that the recoil profile from smaller slimline pistols puts dot tracking on hard mode, but bear with me as I explain how the dashed ring dials things back to normal mode. As the pistol begins to flip up, the dot leaves the framed lens very quickly. Shortly after that the dashed ring enters the frame and the shape in the window gives us a glimpse into the dot’s direction of travel. Depending on one’s grip technique and strength it is possible that the dashed ring will also leave the frame lens. If that happens, then those of us who can apply more grip pressure will be reminded to make use of that extra grip pressure. As the muzzle returns from recoil, the dashed ring will provide a glimpse into the angle the dot is coming back into view. All of the extra input from the dashed ring helps to prepare for the next shot and can inform future practice sessions.

About a week after running the timed drills with the P365 XL and 507K ACSS combo, I shot a local IDPA match with it. I hold a very strong opinion that local IDPA matches are a fantastic way to evaluate our skills and our equipment under stress with less than perfect conditions in a dynamic yet safe environment. My performance expectations for the match were not high as shooting a match with a smaller pistol and optic put me at a disadvantage in the carry optics division. Much to my chagrin, the results weren’t much different from a typical match using typical gear. 

The first stage was a little rough with a miss due to a hit on cover that would have otherwise been an A-zone hit that I failed to call and a slow time. However, the amount of feedback I received from the reticle (including the outer dashed ring) afforded me the opportunity to make adjustments as the match progressed yielding faster times and good hits. 

In my initial review of the reticle, I suggested that the reticle design would lend itself to facilitating transitions and the development of better transitions. This proved to be true during the match. What I didn’t expect or predict is how fast those improvements could occur and that experience is what pushed me from being on the fence about the ACSS Vulcan Dot reticle to now holding the opinion that it is well worth the extra $30 premium over the price of the standard 507K and the “doughnut of death” multi-reticle. Yes, even though I still want a larger aiming reference.

I get that my experience is entirely anecdotal and my evaluation approach is not scientific. However, I can’t deny what I experienced first hand. While “your mileage may vary” applies, I have no hesitation in suggesting this optic with the ACSS reticle for slimline pistols for defensive carry applications.

1 comment

  1. Your experience with the 365 tracks our data showing that getting too familiar with a “gamer” trigger (lighter, shorter) and a full size gun doesn’t imply similar performance with a smaller gun with a heavier, longer trigger pull. Even high skilled shooters desperately want to believe that their skill with the gamer gun will transition easily to the harder-to-shoot gun, but they don’t…and the greater the disparity between the gamer trigger and the carry gun trigger, the greater the performance drop.

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