15 Common Mossberg 100 Atr Problems (With Fixes!)

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if you want to know problems with Mossberg 100 Atr. You come to the correct place.

In this guide, we discussed 15 common problems of this model with unique solutions.

Mossberg 100 Atr Problems

The Mossberg 100 ATR, while generally well-regarded for its affordability and accuracy, does have a few commonly reported issues.

The most frequent complaints often revolve around the quality of the plastic stock, which some users found to be less durable and prone to cracking.

Additionally, some users reported difficulty with the bolt operation, specifically relating to roughness when cycling rounds.

1.  Inconsistent Ejection of Shell Casings

Mossberg 100 Atr Problems


The issue of inconsistent ejection of shell casings could be due to a number of factors. 

Most commonly, this problem arises from a dirty or worn-out ejector

Prolonged use of the firearm without proper cleaning can cause a build-up of residue, hindering the smooth operation of the ejector. 

Another possible cause is the use of low-quality or incompatible ammunition, which can lead to irregularities in the ejection process.


To rectify this issue, regular maintenance and cleaning of the firearm is crucial

Using a small brush and firearm-specific cleaning solution, remove any residue or dirt from the ejector and chamber. 

If the problem persists even after cleaning, consider replacing the ejector. 

Additionally, always ensure the use of high-quality ammunition that is compatible with your Mossberg 100 ATR. 

This not only prevents ejection issues but also prolongs the life of your firearm.

2. Misalignment of Scope Mount


The misalignment of a scope mount on your Mossberg 100 ATR can be caused by various factors. 

This can range from improper installation of the scope mount, using a mount incompatible with your rifle model, or due to wear and tear over time. 

An improperly aligned scope can significantly impair your accuracy and overall performance while shooting.


To rectify this issue, firstly ensure you’re using a scope mount specifically designed for your Mossberg 100 ATR. 

If the mount is suitable and the misalignment persists, it may be due to incorrect installation. 

A proper alignment procedure includes securing the base, aligning the rings, and then carefully mounting the scope. 

You may also need to consider replacing the mount if it shows signs of wear or damage. 

Always remember, if the issue seems complex or intimidating, consulting a professional gunsmith is advisable.

3. Difficulty in Bolt Action


One of the common issues that users face with the Mossberg 100 ATR is difficulty in bolt action. 

The bolt may become hard to operate or it might not cycle rounds properly. 

This could be due to a variety of reasons including cleaning neglect, the presence of foreign particles, or a manufacturing defect.


To resolve this issue, first, ensure that the rifle is clean and free of any debris. 

Regularly cleaning your firearm can prevent many bolt action problems. 

If the issue persists, the problem may lie in the manufacturing of the firearm. 

In this case, it may be beneficial to contact Mossberg customer service for further assistance or even consider professional gunsmithing services if necessary.

4. Frequent Jamming Issues


The frequent jamming issues with Mossberg 100 ATR are often due to the accumulation of gunk, improper handling, or usage of inappropriate ammunition. 

The firearm’s malfunction can stem from a lack of regular cleaning, leading to a buildup of residue in the chamber. 

Furthermore, improper handling methods such as not shouldering the gun properly can cause it to jam. 

Lastly, using non-standard or low-quality ammunition can also lead to frequent jamming.


To rectify this problem, a strict maintenance routine should be followed. 

Cleaning the rifle regularly and ensuring that all moving parts are well-oiled can go a long way in minimizing jamming issues. 

Proper gun-holding techniques should also be practiced to prevent jamming due to improper handling. In addition, always ensure to use the correct type and quality of ammunition for your Mossberg 100 ATR.

5. Trigger Assembly Malfunctions


Trigger assembly malfunctions in the Mossberg 100 ATR can be attributed to several factors such as excessive dirt accumulation, mechanical wear, or improper installation. 

Extensive use of the firearm without routine cleaning and maintenance can lead to a buildup of dirt and grime in the trigger assembly, causing the trigger to stick or fail to reset properly.


To rectify this issue, the trigger assembly should be disassembled and cleaned thoroughly with a suitable gun solvent

Inspect the assembly for any signs of wear or damage and replace any worn-out parts if necessary. 

It’s crucial to ensure that the reassembly process is carried out accurately as improper installation could further exacerbate the problem. 

If the problem persists, professional gunsmith service is recommended.

6. Barrel Overheating


The Mossberg 100 ATR rifle is well-reputed for its performance; however, barrel overheating is a common issue faced by many users. 

This problem primarily occurs due to sustained rapid fire, leading to a significant rise in the barrel’s temperature. 

Overheating can also be a consequence of using low-quality ammunition or firing without adequate cooling periods. 

The key contributing factors are consistent rapid fire, poor ammunition quality, and insufficient cool-down intervals.


To counteract barrel overheating, it’s crucial to manage your firing rate and allow the barrel to cool down between firing sessions. 

Using high-quality ammunition is also a simple yet effective solution. 

For more severe cases, considering a barrel replacement or seeking professional maintenance can be beneficial. 

Remember, the right management of firing rate, high-quality ammunition, and adequate cooling-down periods are fundamental to mitigating barrel overheating.

7. Difficulty in Loading Rounds


The primary cause of difficulty in loading rounds in a Mossberg 100 ATR typically stems from a misaligned magazine follower or a worn-out magazine spring. 

Over time and with extensive use, these components can wear or become misaligned, causing rounds to jam or not load correctly. 

Proper maintenance and regular inspection of these parts can help identify and mitigate these issues early.


To remedy this problem, remove the magazine and inspect the follower and spring for any obvious signs of wear or damage. 

If detected, these components should be replaced. Mossberg offers replacement parts that can be purchased from their official website or from trusted firearms suppliers. 

Remember, handling firearms for repair or maintenance should always be done with utmost caution and respect for the weapon’s potential danger.

8. Poor Factory Stock Quality


The Mossberg 100 ATR has been noted for its poor factory stock quality. 

Users have reported issues with the stock cracking or breaking after a short period of use. 

This issue is often a result of substandard material used in manufacturing, leading to a less durable product.

It’s crucial to note that the longevity of the stock directly impacts the overall performance and reliability of the firearm.


A viable solution to this problem is to replace the factory stock with an aftermarket one. 

Many companies manufacture stocks that are compatible with the Mossberg 100 ATR, offering improved durability and overall quality.

Investing in a high-quality aftermarket stock not only resolves the initial issue but also enhances the longevity and performance of the firearm.

9. Unreliable Safety Mechanism


The Mossberg 100 ATR has been noted to have an unreliable safety mechanism, primarily due to a design flaw. 

Over time, the safety lever tends to loosen, making the firearm potentially dangerous even when set to the safe position. 

This issue stems from prolonged use and wear, combined with a design that does not adequately secure the safety lever.


To rectify this issue, it’s recommended to have the firearm inspected and repaired by a professional gunsmith. 

Regular maintenance and check-ups can help identify the problem early and mitigate it. 

Alternatively, reaching out to Mossberg directly for a factory repair or replacement may be an option, ensuring the safety mechanism is up to the manufacturer’s standards.

10. Difficulty in Disassembling for Cleaning


The Mossberg 100 ATR rifle, while known for its reliability and affordability, often poses a challenge during disassembly for cleaning. 

This is primarily caused by the intricate design of its bolt assembly and the absence of a readily accessible user manual. 

This complexity can make the disassembly process particularly daunting for novice users or those unfamiliar with this specific firearm model.

Key lines: The difficulty lies primarily in the intricate design of the bolt assembly. 

The absence of a comprehensive user manual further exacerbates the problem. 

This problem is most pronounced among novice users or those unfamiliar with Mossberg 100 ATR.


The solution lies in seeking proper guidance and training. 

Numerous video tutorials and step-by-step guides can be found online, which can significantly simplify the disassembly process. 

Keep a regular maintenance schedule and with frequent disassembly and reassembly, familiarity and ease will naturally develop over time.

Key lines: Online video tutorials and guides can simplify the disassembly process. 

Regular maintenance and practice will lead to familiarity and ease with disassembly.

11. Loose Firing Pin Retaining Pin


The cause of a loose firing pin retaining pin often lies in the frequent and heavy use of the firearm, which can lead to wear and tear of parts. 

A loose retaining pin can also be a result of a manufacturing defect or inadequate maintenance. 

Regular inspection of the firearm, focusing particularly on the firing pin retaining pin, can help identify this problem early on.


The solution to a loose firing pin retaining pin is generally replacement or tightening. If the issue is due to wear and tear, the retaining pin should be replaced with a new one. 

However, if the retaining pin has simply loosened, it can be tightened back into position. 

Always ensure to use the correct tools for tightening or replacement to avoid causing further damage. 

Professional assistance is recommended if the problem persists or if you’re unsure about the process.

12. Imperfect Feed Ramp Design


The Mossberg 100 ATR is often criticized for its imperfect feed ramp design. 

This flawed design can lead to inconsistent feeding of the ammunition, resulting in frequent misfires and leading to unreliability during use. 

The angle and finish of the feed ramp might not be ideal for smooth, reliable feeding of rounds into the chamber.

Important note: The quality of the feed ramp directly impacts the reliability of any firearm. 

An imperfect feed ramp can lead to malfunctions, compromising the consistency and safety of the firearm.


To rectify the problem with the feed ramp on the Mossberg 100 ATR, users might need to consider some modifications. 

This could involve polishing the feed ramp to improve the surface finish or adjusting the angle for better ammunition feeding. 

It is recommended that such modifications should be done by a professional gunsmith to ensure safety and maintain the integrity of the firearm.

Remember: Addressing the feed ramp design flaw will not only improve the reliability and performance of your Mossberg 100 ATR but also ensure your safety during its use.

13. Sub-Par Accuracy


The sub-par accuracy of the Mossberg 100 ATR could be attributed to a variety of factors. 

One common issue might be the quality of the ammunition used. 

Poor quality or incompatible ammunition can significantly affect the precision of the firearm. 

Another factor could be the barrel condition – a dirty or damaged barrel can impact bullet trajectory, leading to inconsistent shot groupings. 

Also, issues with the rifle’s scope, if present, could contribute to the problem.

Poor quality ammunition, an unclean or damaged barrel, and scope problems are often the primary culprits behind the sub-par accuracy of the Mossberg 100 ATR.


Addressing the issue of sub-par accuracy involves tackling each potential cause. 

First, ensure the use of high-quality, compatible ammunition. 

Second, regularly clean the barrel to eliminate any residue that might affect bullet trajectory. 

If the barrel is damaged, consider replacing it or getting professional gunsmithing help. 

If the rifle has a scope, make sure it is properly calibrated and free from any defects.

Using high-quality ammunition, maintaining a clean, undamaged barrel, and ensuring a well-calibrated scope can drastically improve the accuracy of the Mossberg 100 ATR.

14. Excessive Recoil


Excessive recoil in the Mossberg 100 ATR could be attributed to a variety of factors. 

This typically results from improperly fitted stocks, higher caliber ammunition, or inadequate shoulder support while shooting. 

Incorrect shooting techniques can also contribute to greater recoil.


Mitigating excessive recoil can be achieved by addressing these causes. 

Ensure that the stock fits properly and comfortably, preferably with a recoil pad. 

Consider using lower caliber ammunition, or employ proper shooting techniques which include positioning and grip. 

Regular practice under supervision can also significantly reduce the perception of recoil.

15. Inadequate Magazine Capacity


The Mossberg 100 ATR has often been criticized for its limited magazine capacity. 

It’s primarily a bolt-action rifle, designed for hunting and target shooting, which typically don’t require large magazines. 

However, this lack of capacity can be a drawback in situations where rapid, multiple shots are necessary.


The issue of inadequate magazine capacity can be addressed by opting for extended or high-capacity magazines that are compatible with the Mossberg 100 ATR. 

These are readily available in the market and can significantly increase the number of rounds that can be held at one time. 

However, it’s important to ensure that these modifications comply with local laws and regulations regarding firearm modification.


In summary, while the Mossberg 100 ATR has gained a reputation for being a reliable and efficient firearm, it’s not without its problems. 

Users have reported issues such as difficulty in trigger adjustment, limited availability of aftermarket parts, and occasional inconsistencies in accuracy. 

However, despite these potential drawbacks, the affordability, durability, and overall performance of the Mossberg 100 ATR make it a compelling option for hunting enthusiasts and hobbyist shooters. 

It is essential, though, for potential buyers to evaluate their specific needs and preferences against these identified issues before making a purchase decision.


What does Mossberg ATR stand for?

ATR in Mossberg ATR stands for “All Terrain Rifle”.

How much is the Mossberg Model 100 ATR?

The price of the Mossberg Model 100 ATR typically ranges from $300 to $400, depending on the condition and market demand.

Which Mossberg shotgun is the best?

The Mossberg 500 is often considered the best due to its versatile use in both hunting and home defense situations.

What is the effective range of a Mossberg?

The effective range of a Mossberg shotgun varies but is commonly around 40 to 50 yards for most models.

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