In wireline, there are a handful of moments that permanently change how you operate. One of those moments hit me hard during a wireline and perforating run a few years back. We were prepping a standard pump down perforating job. The plan was solid, the wireline truck was prepped, our wireline control systems checked out, and the perforating gun string was staged.

But during assembly, I saw something I’ll never forget—an exposed detonator, fully crimped to primacord, sitting unguarded while another operator reached over the bench to grab a wrench. One dropped tool could’ve triggered it. One accidental impact. One mistake.

We got lucky that day. But that was the last time I ever let our crew wire guns that way. What followed was a complete overhaul of how we handle gunbuilding, particularly when it comes to protecting live detonators. It’s now a core lesson I pass on in every one of my wireline courses.

The Traditional Gunbuilding Risk

Traditionally, we built guns in sequence—crimp the detonator, screw on the sub, install the EB, attach the next gun, and repeat. It was efficient and it worked… most of the time.

But that workflow left the detonator exposed for just long enough to be dangerous. Once that deto is crimped, it becomes a live device, and leaving it unprotected—especially while threading on the next sub—creates a window for something to go wrong.

Nicked wires. Pinched wires. Exposed leads. I’ve seen it all. And when you’re building a long string for a multi-stage perforation well, all it takes is one exposed deto to turn a safe job into a dangerous one.

Introducing the Prepped Gun Method

After reviewing several near-misses and discussing best practices across crews, we made a simple but powerful change: prep every gun before building the string. This meant:

• Crimping the detonator inside the housing

• Covering it immediately with the sub

• Feeding wires through carefully

• Assembling the full gunstring only after every gun had been prepped and protected

This process may take slightly longer on the front end, but it’s far safer—and that matters more than shaving off a few minutes in the yard.

Our New Gunbuilding Procedure

We now use a method that reduces the chance of damage and eliminates the exposure window. Here’s how we do it step by step—now included in our standard wireline service company protocols and field manuals.

1. Detonator Prep and Protection

• Remove the carrier from the gun housing to check that the primacord makes contact with every charge and that the through wire is correctly routed.

• Insert the carrier mostly back into the housing, with about 2 inches exposed.

• Crimp the detonator to the primacord on the bottom side of the gun.

• Slide the carrier fully into place and install the snap ring.

• Immediately protect the crimped detonator by threading on the sub—never leave it exposed.

2. Wire Routing and Sub Connection

• Organize the wires, feed them through the EB port in the sub.

• While holding tension on the wires, screw the sub onto the bottom of the gun.

• Use a second operator to maintain tension until the second O-ring passes through the threads—this helps avoid pinching.

• Once past the second O-ring, a small amount of slack is introduced to prevent tension damage.

3. Wire Cutting, Scotch Locks, and Inspection

• Cut all wires to 3–4 inches (about four fingers in length).

• Scotch lock connections must be:

  • Fully inserted

  • Crimped securely

  • Tug-tested individually

  • Visually inspected for nicks or damage

• Run fingers down each wire to confirm insulation integrity before finalizing connections.

4. Final Checks and Grounding

• A second operator—not the one who did the wiring—performs the final quality check.

• We now require a grounding spring to be installed in each port (referencing our Grounding Springs Best Practice).

• The gun is not considered ready for assembly into the string until this process is complete.

The Safety Gains

Since implementing this alternative gunbuilding process, we’ve seen a massive improvement in:

• Fewer damaged wires from threading subs

• Reduced detonator exposure during assembly

• Increased reliability during switch tests

• Elimination of intermittent gun failures that once plagued us on long strings

• Better depth control during wireline well logging, with cleaner data from CBL logs and caliper logs

It’s now standard practice in all of our cased hole wireline operations, particularly for perforation wells and high-shot-count wireline perforating gun builds.

What Is Wireline Without Discipline?

Wireline logging is more than tools and software—it’s process. It’s discipline. It’s knowing that the wireline equipment you put in the hole was checked, double-checked, and built with safety in mind.

Whether you’re building a basic toolstring for production logging services, preparing for a pipe recovery run, or deploying a perforating system for a cased hole solution, your wireline success depends on how you start. And in wireline services oil and gas, you don’t get many second chances.

Why This Matters in the Wireline Services Market

In today’s oilfield services company landscape, clients expect speed, precision, and zero safety incidents. That puts pressure on every wireline provider, every wireline truck, and every engineer running wireline control systems.

Cutting corners on something as critical as gunbuilding isn’t just a risk—it’s a career-ender. A single misfire, accidental detonation, or damaged logging cable can shut down a frac, delay an entire pad, or even put people in danger.

That’s why we now train this updated process across all our crews and teach it in our wireline courses.

From the Bench to the Field – Making It Stick

Change only works when crews believe in it. We’ve found success by integrating this SOP into every level of our operations:

• Yard prep checklists

• Gunroom safety briefings

• Live demos during crew meetings

• Visual inspections before every loadout

• Mentor-led reviews during field builds

New hires learn this as their first intro to what is wireline in oil and gas. Experienced operators treat it as gospel.

Conclusion – Building Guns the Right Way

This isn’t just a best practice. It’s a field-tested evolution. A process born from experience, adapted under pressure, and proven to work in real-world conditions.

If you’re a wireline company looking to reduce misruns, improve safety, and boost client confidence, this is where you start. Train your team to build guns the right way—every time.