Why Does My BB Gun Keep Jamming?

Why Does My BB Gun Keep Jamming

It can be so frustrating. You have a nice new BB gun but the enjoyment of shooting is ruined by having to keep clearing out jammed BB’s in the mechanism, why does it keep jamming?

If your BB gun keeps jamming then it’s most likely to do with the BBs themselves, rather than the gun. Check whether the size of the BBs is correct for the gun you’re using and try a batch from another manufacturer.

Most Likely Reasons

Wrong Size BBs

It sounds pretty obvious, right? But you’ll be surprised (or maybe you won’t be) how often this happens. Hence why it is top of the things to check first. Even a seasoned shooter can make mistakes so just double-check you’ve got this right.

Typically, BBs are made of steel which is plated in either zinc or copper (this helps prevent corrosion). They measure about 4.5 mm 0.177 inches) and are around 0.34 g in weight. You will also find lead balls that are used which are a bit heavier.

These numbers are important as we’re talking about tiny tolerances here. If your BBs are slightly smaller or slightly larger than this (and it doesn’t have to be much either way) then you’re going to run into problems, primarily related to the magazine feeding the BBs into the breech.

Quality / Condition of BBs

There are two points here and both can cause problems with jamming.

Firstly, like with airgun pellets, don’t be tempted to buy cheap. It’s a false economy and these BBs, although they are cheap, will cost you in the long run. Buy from a recognized brand and don’t get the cheapest ones out there. Look for the reviews and choose wisely.

Another thing to think about, even the best quality BBs will deteriorate over time. If you’ve had yours sitting at the back of a drawer for a few years (or worse, outside) then don’t expect too much from them. You might get lucky, you might not. Certainly, if you experience jamming after using an old load of BBs, this will probably be the reason.

It’s not always the case but some of the best BBs are quite shiny as they undergo a polishing step as part of the production. This helps with their accuracy and will reduce the number of jams as well.

One more thing to think about here. BBs need to be a sphere, a perfect sphere. The cheaper quality BBs don’t have as good a manufacturing process as the more expensive brands. It is most likely because of this that some BBs come out not perfectly spherical.

You’ll probably find if one BB isn’t quite round, then most of them in the bottle will be off also. You’ve got a couple of options here, persevere with it or just send them back – I know which I’d do (and have done in the past).

Incorrectly Loaded BBs

It’s difficult to give specifics here as there are several different types of BB guns.

For instance, a rifle or a pistol – depending on what you get, the loading mechanism will be different. Typically though, they’re fed into the magazine and most can be a pain in the backside to load!

f you’re lucky enough to own a Umarex MP40 then you’ll know what I’m talking about for sure. It’s easy to get frustrated with this loading process and try and jam them in, I totally feel your pain.

You’ll either need to slow down a bit or try a trick I learned from YouTube a while back, load your BBs into a drinking straw and use this to feed them in. It works! Well, most of the time. Patience is the key here.

A final point is if you’re BBs are not the best of quality (see above section about this) then you’ll probably feel something isn’t quite right when you’re loading them in.

If you want to get the best possible BB’s for your gun without having to spend top-dollar, take a look at these guys. They don’t just stock BB’s btw, you’ll get a lot more choice here than other mainstream websites and also, free delivery on larger orders.

Other Possible Issues

Power Related

If your BB gun is CO2 powered, which it probably will be – there could be an issue with your power delivery. Perhaps you have a leak! The point is, if your CO2 canister isn’t delivering the correct amount of power then it could cause problems with the internal mechanism, this is noticed more with blow-back BB guns.


We’ve obviously spent a lot of time concentrating on the ammunition here and there’s a good reason for this. In all my forty years of experience, the VAST majority of problems I’ve seen with BB guns have either been user-related (not following the loading instructions carefully) or ammunition related (see above).

There is a chance though that a manufacturing defect crept into the production of your gun and slowly, over time, things have failed. It’s probably out of warranty so you then have to make the decision to try and fix it yourself, replace it or live with the jamming problems.

If it was me and considering these guns aren’t that expensive, I’d have a crack at seeing what’s wrong. The worst that can happen is you break it totally and if you were going to replace it anyway, then this doesn’t really matter, does it?

It’s a bit difficult for me to give you instructions on how to strip down your gun as I don’t know what you’ve got but these things are made pretty simply.

A common BB pistol is the Daisy 340. With this gun, you can clearly see the flat-head screws on the grip:

As you take these covers off, there’s a spring at the back of the trigger, make sure you don’t lose it!

Next, remove the barrel by pressing the lever down after pushing the button (marked with the blue arrow) from behind. This pin has a spring also, again – keep it safe!

Then push the barrel forward to detach:

From here, there’s really not much to it. Check for any obvious problems or damage internally, particularly where the magazine feeds the BB into the breech. It’s a bit of a long-shot this one but worth a go if you have nothing else to lose.

The worst scenario is you’ve at least learned how to strip down a BB gun and understand a bit more as to how it works!


Related Questions

Why Does My BB Gun Leak CO2?

A BB Gun will probably be leaking due to an issue with the seal. A possible solution to this is to tape your CO2 canisters before they are inserted and also lubricate the seal itself. Check out Why Does My BB Gun Leak CO2?

How Dangerous Are BB Guns?

A BB Gun can certainly be dangerous and the same safety procedures applied as a regular firearm. This may seem like overkill as the projectile isn’t as massive and the power behind the BB gun isn’t as much, however, the BB can still do significant harm if it hits the human body, especially unprotected eyes. You can find our great article on how dangerous BB guns are.

Can I Use A BB Gun For Self Defense?

You could try but it would be a dangerous thing to do. This is not what they were designed for and arguably you’d be better off throwing it at the attacker. Use a BB gun in the backyard, shooting targets or tin cans. If you want to protect yourself, you’ll need something else. For loads more information relating to using a BB gun for defense, check out this post.


Conclusion: Why Does My BB Gun Keep Jamming?

If your airgun smokes, then this is something different and you may want to check out my article here.

If you’d like to know the difference between a BB gun and an airsoft gun, then take a look here.