Common SIG Rattler Problems and Solutions

This little weapon packs a.300 Blackout punch. Without the ATF, it needs to be 26 inches long overall. It has 5.56 ballistics, which might not be sufficient. However, no matter what position the gas valve system is in, the supersonic ammo cycles flawlessly.

Despite all this, the gun has mostly positive reviews. However, there are some problems with this rifle. The most common problems with the SIG Rattler are proprietary parts, will not cycle, magazine/feeding issues and trigger issues.

I will discuss the solutions to all these problems and user reviews in this article. So read on till the end!

Features & Specifications of SIG Rattler:

Cartridge.300 AAC Blackout and 5.56.
Capacity30 rounds.
Barrel Length5.5 inches.
Weight5.7 pounds.
Length23.5 inches.
Width2.8 inches.
Height8.0 inches.
Safety90 degree ambi safety.
SightsPicatinny rail for mounting, iron or optical sights.
Common SIG RATTLER Problems

Common SIG Rattler Problems and Solutions

The owners deal with many common SIG Rattler problems. Here are some of the issues and how to solve them.

Quick Overview of the Problems and Solutions

Proprietary PartsReplace with other parts.
Will Not CycleTroubleshoot.
Magazine/Feeding IssuesTroubleshoot.
Trigger IssuesReplace trigger.

1. Proprietary Parts:

In comparison to an AR, the MCX range from SIG is bulkier, more expensive, and uses exclusive parts.

The parts portion is important if you want to modify something like a charging handle or trigger and have to purchase the exact part. It is typically more expensive than the AR equivalent.

The Fix:

You can replace each parts by this way: For an upper replacement, either a full MCX/Virtus upper would need to be attached to your present lower. Or your current Rattler upper would need to be fitted with a non-Rattler BCG and MCX/Virtus barrel.

If you want the latter, you’d need to locate a handguard designed specifically for the Rattler that is long enough to cover more of the barrel.

To use the same uppers like the handguards for the Rattler, [legacy] MCX, and Virtus chassis (“uppers”), you would need to switch the Rattler BCG (recoil assembly, not the bolt), which is different from the MCX/Virtus. * ETA: MCX.

Virtus bolts differ as well and must be used with the appropriate barrels. However, a new barrel kit will include the appropriate bolt.

Additionally, Sig does seem to offer an 11.5″ MCX/Virtus barrel but not a 10″. You can put up a plan that fits your needs and budget using the individual Virtus components that Sig sells.

Or you can get a whole upper kit that includes everything you required to convert the system to work with a conventional AR lower.

2. Will Not Cycle:

There’s a failure to load MCX Rattler Canebreak properly. Especially in brand-new, 220gr subsonic ammunition. Cycling is always a problem with these. The fresh round may also get stuck at an angle.

The Fix:

In a 556 magazine, an ogive profile causes the Blackout bullets scrape against the “556 cartridge shoulder ribs.” This causes a heavy 300 Black Stack in a 556 mag to bind and slow down.

There simply isn’t enough rattle in the Rattler to shake them up when the low-power subs are added.

The typical solution is to take a 300 Blackout or PMag and slightly reduce the ribs with a wood rasp. The Rattlers’ included 556 Lancer might theoretically be modified.

You could try these till your new 300 Blk Lancers arrive. Bullets like 110s, 125s, 147s, and similar ones often don’t rub in the 556 mags unless they’re strange and seated long.

3. Magazine/Feeding Issues:

The gun may completely stop abruptly. During a shooting it is risky.

The Fix:

Rattler was a little particular about the magazines. Buying the 300BLK mag from Magpul will solve the magazine issue. You should also get a silencer.

The rattler is a single-round, subsonic firearm without a silencer.

This comes straight from the SIG Helpdesk. Without the can, I haven’t been able to get it to properly cycle subsonic.

4. Trigger Issues:

A trigger set component may be out of design. A blown primer may occasionally become caught under the trigger. So that adheres to and conceals itself in the AR’s grip screw recess beneath the trigger.

Be mindful of how quickly other triggers are consumed by the MPX before you insert a costly binary. The severe bolt cycling is known to damage triggers not designed for the MPX platform.

The Fix:

An amazing trigger is the SSA. They produce a special MCX model. You won’t be let down.

The stock Timney can be changed with an AR9. Insert the binary trigger there. You may also replace the stock trigger with a Geissle.

However, the Rattler’s parts may be damaged by the Geissle due to revisions made following the recall. With a Magpul K2+ that works exceptionally well, a Rattler conversion upper was attached to a Radian AX556 bottom.

If you’re still debating whether to replace the grip on yours, it would be worthwhile to look into as I’m rather confident it will fit the OEM Rattler lower.

User Feedback on SIG Rattler

For those who are familiar with K-configured MP5s and have a 5.5-inch barrel, the inclusion of a hand stop would be a significant improvement. Given that the K configured MPX comes with one standard, this would have been a wonderful addition to the civilian firearms.

The three-position pistol brace is solidly built, with some lateral play. This is appreciated by the users. The people may not enjoy shooting the Rattler in an indoor range. Regarding magazine compatibility, the GI, Pmag (.300), and the supplied Lancer magazine will operate without a hitch.

The trigger is nothing special and feels like a typical GI trigger. Both strong and support side shooting may be done with ease because of the ambidextrous controls. Users also appreciate the idea of a piston-driven system.

Users do tend to make some modifications. The most common changes made are to the side folder for the telescoping brace using the SBA3, geissele trigger, and CH. This is because the OEM CH is too small.

With more units shifting away from short-barreled 5.56, a 300 Blackout in a package that is roughly the same length as an MP5K is needed, according to the users.

Frequently Asked Questions (FAQs)

Are there any suppressors that are recommended and warrantied for the 5.5” barrels?

If you need extremely short barrels for a 5.56, contact KSGM. There is Surefire on 5.56. A few Rugged Suppressors, the Surge, the Wolfman and the Nomad 30 are good options too.

Is the gas system on the 6.75 barrel different that the one on the 5.5 barrel?

Yes. Virtus gas system’s 1.25″ longer than Rattler’s.

Is the SIG Rattler full auto?

Yes. It can be semi-auto and full-automatic.


Although the firearm is quite amazing, a few things should be included. This list has a hand stop, a better pistol brace, and a better trigger are a few enhancements. The Rattler is not inexpensive and at this price point, ought to have at least a hand stop.

The handgun is simple to use and has acceptable recoil, allowing for quick follow-up shots. The Rattler is a superb firearm in my opinion, and the two-position gas system is also alluring.

The borderline is that it shoots in all configurations quietly, smoothly, and reliably. Gas is rarely noticeable while using a suppressor when using any full-size AR as a weapon.

So I would definitely vote in favor of this one!

Related Posts:

Related Posts