Burnt Latke
spudtech rifled barrel tests


"Increase Accuracy and Safety with Rifled Barrels.." is what we read at spudtech.com and the claim we set out to test. That's right, rifled PVC barrels for potato guns. These barrels are hand made at the Spudgun Technology Center using custom machinery and mysterious techniques. The price is a steal, only a little more than the raw materials themselves. We purchased our 1.5" rifled barrel over the telephone directly from Joel Suprise, the owner of STC. It arrived at Burnt Latke headquarters on time packaged in a triangular box. Inside the barrel was a note about safety and a reminder that the barrel is unidirectional. The barrel is usually marked on the muzzle end but ours came pre fitted with a 2" male thread which made it easy to figure out which side faces forward.

The initial plan was to breech load with an indexed slug cutter made from rifled barrel stock. When ordering, Joel suggested doing away with the slug cutter and putting the knife edge directly on the breech end. Joel does have a technique for index aligning the rifle grooves which is used primarily for barrel extensions. The pass-through barrel design with knife edge extends 1.5" into the combustion chamber, barely missing the forward electrodes and occupying 150cc of our L1 launcher's 2600cc chamber. We ordered our barrel a little long with the intent of fine tuning the C:B ratio later. It showed up with 56.5" of effective barrel giving us a ratio of 1.37:1. The barrel we used for comparison was 1.5" diameter, smooth bore with an effective length of 56" and a ratio of 1.43:1. The smooth barrel was breech loaded with a slug cutter for these tests.

  rifled barrel and slug cutter

The knife edge on the rifled barrel had a slight inside taper and a shallow outer taper. The profile of this knife edge was much thicker than the knife on the slug cutter we planned to use for the tests.

During initial testing, it became obvious the shape of the rifled barrel's knife edge would need to be modified. While loading, the spuds would begin to split about 1/4 of the way in. The spuds pictured here are crisp and green, the softer, ripe spuds also split with this barrel knife. The knife taper was an easy fix but what stood out was the ease and speed of loading. The breech mount barrel knife works great. Just pop it on and it's done.

split spud
grinding with Dremel

A Dremel was used to add a more aggressive inside taper. The outer taper was further ground down to achieve a thinner profile knife edge.

A ghetto lathe was made with some blocks of wood clamped to the table. The barrel was rolled toward the wooden blocks by hand. The stand with clamp could be replaced by a someone holding the Dremel against something sturdy.

ghetto lathe  
finished knife edge

The final product is ugly, full of dents and loads like a dream. The spuds seats completely with a couple good smacks and the splitting of the slugs has been eliminated completely. The barrel was tested again and worked flawlessly, it was time to begin the tests. First stop, indoor range at 50 feet.