Spend just a few minutes browsing the internet and it becomes clear how James Holmes was able to stockpile 6,000 rounds of ammunition without any alarms sounding. Huge amounts of ammunition can be purchased online in a matter of minutes and can be shipped straight to customers' doors, no questions asked.

Yet those familiar with gun ownership in the US are unlikely to have been surprised.

BulkAmmo.com is one of many websites which allow for the purchase of lots of rounds at knockdown prices. On the website one can buy 1,000 .223, 62grain TulAmmo rounds, which can be fired by an AR15 assault rifle, for just $250, or 25 cents a round.

The website, like others the Guardian explored on Monday, offers incentives in the form of discounts the more ammunition you buy – four cases of 1,000 rounds comes to $980, or 24.5 cents a round.

Customers can essentially buy as much ammunition as they like. BulkAmmo.com had 18 cases of 1,000 .223 TulAmmo rounds "ready to ship". The Guardian selected all 18 – 18,000 rounds – and was just a healthy credit card away from completing the transaction. It is illegal to ship ammunition to New York City, where our office is based, so we entered the address of a hotel in Aurora and were promptly told that in return for $4,737.30 (including a $327.30 shipping and handling fee) the 18,000 rounds could be delivered within days.

Ammunition websites will ship rounds almost anywhere in the United States (noted exceptions are the state of Massachusetts and the cities of Chicago and New York), without documentation.

Luckgunner.com stocks Fiocchi .223 remington rounds in boxes of 1,000, described as "perfect for your AR-15!". When the Guardian perused the website on Monday there were 41 boxes in stock. Again, we were able to follow the purchasing procedure through – potentially getting 41,000 rounds delivered within three days, for $17,428.39.

Buying the guns themselves is a little more tricky. Customers can select, and pay for, a gun on any number of websites, but unlike ammunition cannot have the weapon mailed direct to a home address.

When buying online the customer has to elect a local Federal Firearms Licensee (usually just a gunshop) to have the weapon sent to. The person selling the gun then transfers the weapon's license to that shop. The customer has to then go and fill in forms at the shop before taking the gun home.

The exact procedures differ from state to state, but the federal government always requires purchasers to go through the National Instant Criminal Background Check System, which checks whether individuals have criminal records or are otherwise not allowed to purchase weapons.

In Colorado, similar background checks are made at state level before the purchaser can take the gun home. The Guardian spoke to one Federal Firearms licensee on Monday who said she did not act as a licensee transfer any more, but had done many transactions in previous years. Asked how long it usually took for an individual to clear the background checks and take the gun, she said it would often be the same day.

© Guardian News and Media 2012

[Ammunition via Shutterstock]