One of the most important decisions you can make before setting out on a micro ARP (besides what upper/barrel length to choose) is what caliber, specifically, what cartridge, to focus the build around.
Broadly speaking, you will ultimately need to go with either a pistol caliber or a rifle caliber. There are advantages and disadvantages to each which, from a high level, will be covered here.
Benefits and Drawbacks of Pistol Calibers
In the world of pistol calibers, the 9mm reigns supreme, though there are also other options, like .45 ACP. Regardless, the relative advantages and drawbacks of each are more or less the same.
With a pistol caliber, ammo will generally be cheaper and more available. They also produce less recoil and tend to perform well from shorter barrels. Some pistol calibers also produce a smaller risk of overpenetration.
Another thing about pistol calibers is that the ammo is compact and usually pretty light, which means they work well with smaller, micro ARPs where size is a concern.
Additionally, there are bufferless micro ARP uppers that you can choose for some pistol calibers that will cut back on the size and overall footprint of the platform even further.
Now, the tradeoff with choosing a pistol caliber is that it almost invariably won’t offer the same stopping power as a larger rifle cartridge.
The other thing is that pistol calibers also perform pretty poorly across the board at greater ranges – but that should not be a concern here as most micro ARPs are destined for close-range engagements.
Benefits and Drawbacks of Rifle Calibers
You’ll have a lot of options when it comes to rifle calibers for your micro ARP, too. Some of the more popular ones are 5.56, .223, .300 BLK, and 7.62 Soviet, although there are others, too.
These offer higher stopping power across the board, so they give you the benefit of the “rifle firepower in a pistol footprint” argument.
They are generally, however, more expensive, and they will produce a lot more recoil. Some also don’t perform as well out of shorter barrels, too.
A big outlier here is .300 BLK, which actually performs very well not just from very short barrels, but from suppressed barrels, too.
Overpenetration at close ranges can be a risk, but since you get the extra power, it’s sort of a balance.
Also, despite the shorter barrel, rifle calibers tend to perform better at greater ranges. Although, to be fair, as with the pistol caliber argument, micro ARPs are usually reserved for fairly close engagements.
One other potential drawback to rifle cartridges is the amount of space they take up, and thereby the weight.
Where to Get Parts for Micro ARP Builds
At the end of the day, whether you choose to build a micro ARP around a rifle caliber or a pistol caliber is completely up to you. There is no universally right or wrong answer to this question, and there will be relative benefits and drawbacks to each proposition.
That said, there is one solid answer to the question: where is the best place to get micro ARP parts online, and that place is MCS Gearup.
MCS Gearup is fully sold into the super-short ARP craze and carries a ton of parts for truly micro-sized AR builds, including assembled AR15 pistol uppers, barrels, muzzle devices, and much more. They even carry completely bufferless builds for AR pistols.
For more information or to see what sorts of options they carry, take a closer look at their website via the link above.
For more information about Buffer Tube and M Lok Rail System Please Visit : MCS Gearup
