Mossberg MVP Maintenance

A customer recently brought in a Mossberg MVP bolt action rifle chambered in 6.5 Creedmoor. Mossberg’s MVP series is basically a bolt action rifle feeding from detachable magazines. The patented design is compatible with AR-15 (223 Remington/5.56mm NATO) or AR- 10 and M1A/M14 (7.62mm NATO) magazines, depending on the chambering. The MVP Predator, my customer’s model, is a compact rifle with a gray laminate, sporterstyle factory stock which allows the use of both M1A/M14 and AR- 10/SR-25-style magazines.

This customer rarely uses her rifle other than for hunting purposes. This issue was, despite having no apparent obstruction in the action or barrel, she was unable to lock the bolt in the closed position. After further examination and a few attempts at closing the bolt, there seemed to be an issue with the bolt’s extractor or the rails that the bolt glides across when pulling it reward.

To further attempt to resolve the issue, I retrieved an assortment of small rasp files, three different sizes of punches that will decreased in diameter, and a endoscope to have a better view of the issue within the chamber. Having the proper tools for the job always helps. An endoscope allows viewing the entire interior length of rifle barrels such as the lands and grooves and can be very helpful if you are having issues The bolt stopped as if it is getting caught during its forward loading motion. with accuracy.

Most endoscopes are able to give you a cleaner, welllit image that can either be saved for examples or to provide a visual detailed image towards explaining the issues to your customer. The descending size punches help remove pins the proper way rather than creating small metal fragments that can cause more issues if the surface is not smooth. The small rasp files are used to remove material in hard to reach places slowly so as to not create an uneven surface.

Having a squared end or a pointed end will help avoid the jabbing effect into areas that have soft material. After clearing the rifle, I first removed the bolt from the action and inspected the areas on the head of the bolt where the rim of the casing is pushed forward or grabbed by the ejector and removed once the round is spent. Looking at the bolt, it did not seem to have any deformations or mechanical issues that could be seen. I disassembled the bolt to check the firing pin as well as the ejector spring.

The spring and firing pin and spring were still in good condition and with plenty of retention. To take apart the bolt to inspect the firing pin, spring, and ejector, I started by using a small punch to lift the assembly on the rear end of the bolt and turn it counter clockwise to unlock the firing

Using a pointed round punch will help allow the pin to slide around the bolt housing and release tension once it has made a half turn to the open position. There will be enough tension so that you are able to feel the pressure release, yet it will not completely eject. pin from the bolt housing. Once the firing pin was removed, the a pin that holds the head of the bolt was able to slide out and the head inspected. I then used the endoscope to get a good view past the ejection port and near the end of the barrel.

Sliding the camera down past the ejection port, the close-up view allowed me to see that the guides the bolt glides on had a small piece of metal chipped on one of the guides. This was causing the bolt to jam and stop the cycle from loading and ejecting. I used a small square rasp file to remove the small burr of material that was stopping the bolt from locking into position. Using small, even, short strokes, I focused on how much material to be removed.

If too much is removed there will be a drop in the way that the bolt The head of the bolt has standard wear in the proper places and the ejector is still rigid and firm. After checking the bolt and the internal components, I inspected the action to see if there was any build up or burrs that could be stopping the bolt. Using an endoscope, I could see that the center of the ejection port guide rail had noticeable wear and a slight bend.

Using a small pointed rasp file I smoothed the surface flat and even. rides forwards, which could create a safety issue for the user. Now that the materiel had been carefully removed, I placed the bolt into the lock position slowly to con-

Small amounts of debris are capable of causing other issues such as this one or developing a build up problem where the bolt’s travel is restricted, creating re-chambering issues. firm the bolt would not get caught where the material was removed. I then applied a small amount of oil to the bolt to allow less friction and smoother transition when chamthe bolt so that it smoothly guides through the chamber during the cycles.

I checked my work with snap caps to confirm the bolt will lock and eject cartridges properly without getting jammed or caught. The completed work was then returned to my happy customer for her next bering anew round. I find Hoppe’s Black Precision Oil helps with rust prevention and heat dissipation as well as being a great lubricant. I used a small amount on the head of hunting trip.

AG Far I repeated this process multiple times to ensure functionality of the extraction, ejection, and smooth movement of the bolt’s travel to complete the cycle.