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How to fit a barrel bolt

Updated: October 2026

You have a surface bolt and a timber door, and the job fails in one of two ways: the shoot binds, or a screw head shears before the keep is even on. How to fit a barrel bolt is mostly alignment. One screw goes in loosely, the body is levelled, and the keep is marked with the shoot already thrown. This page is that sequence, plus the two failures reviewers actually report. It is not a ranking of the twelve listings on the [door bolt comparison](/hub/door-and-window-security/door-bolt). Peter F. followed DIY Doctor and Handle King, with the review pattern from those amazon.co.uk listings, updated October 2026. A qualifying purchase can earn a commission at no extra cost to you.

You have a surface bolt and a timber door, and the job fails in one of two ways: the shoot binds, or a screw head shears before the keep is even on. How to fit a barrel bolt is mostly alignment.

Our top picks

SAYAYO SAYAYO padlock-hole slide bolt

Best overall

SAYAYO SAYAYO padlock-hole slide bolt
9.2/10about £8.49
View offer
JelKen JelKen 75 mm slide bolt, silver

Best value

JelKen JelKen 75 mm slide bolt, silver
9.0/10about £3.79
View offer
n/a Necked barrel bolt 75 mm, chrome

Rank 3

n/a Necked barrel bolt 75 mm, chrome
8.8/10about £4.99
View offer
On this page
  1. 1.Before you drill
  2. 2.Fix the bolt
  3. 3.Fix the keep
  4. 4.If it sticks or the screw snaps
  5. 5.When to stop

Before you drill

Confirm the faces before you choose the height. A straight bolt needs the door face and the frame face flush. A necked bolt is the one when the door sits inside the frame. Forcing a straight bolt onto a rebate is how the keep never lines up. The choice of type and length is on the door bolt buying guide. Refuse the job when this door is a final exit, a flat entrance, or a certified fire door. A door on an escape route should open without a key and without more than one mechanism. A bathroom bolt sits at hand height. Hold the bolt so the shoot does not overhang the door edge. Outdoor coach bolts belong on the shed door bolt page.

Fix the bolt

On sound timber, mark one hole, drill a pilot about 2–3 mm and about 5 mm deep, and drive that screw loosely. A drill at full speed with no pilot is how the heads shear, which is the complaint on several alloy and chrome listings. If the head looks likely to round off, stop and change the screw. With one screw holding the body, set a short level along the bolt until the shoot runs square to the frame. Then pilot the remaining holes and tighten them in turn. A bolt fixed on a slope will bind the first time the door drops.
SAYAYO SAYAYO padlock-hole slide bolt

Testsieger

SAYAYO SAYAYO padlock-hole slide bolt
9.2/10about £8.49
View offer

Fix the keep

Throw the bolt fully before you mark the keep. Offer the keep up, slide the shoot in, and look for a little clearance so the bolt does not jam against the far side of the hole. A keep that is tight on day one will stick when the timber takes on moisture. If the architrave stands proud, chisel a shallow recess so the keep sits back in line. Do not bend the shoot. Close the door and throw the bolt several times. A practical check is ten throws. If it grates, move the keep.

If it sticks or the screw snaps

A shoot that sticks after a dry week was often fitted tight, and UK timber moves in damp weather. Move the keep, or ease the hole, before you replace the bolt. A silver JelKen review, the best value slide, reported being shut in the bathroom. Nobody on the landing can free a plain slide. A sheared screw head is a different fault. Back the stump out if you can do it without splitting the stile. If the frame will split, stop. Do not oil a misaligned bolt and call that a repair. If the casting has cracked, replace the bolt.

When to stop

Stop if someone is shut in and the bolt will not withdraw. If the door is a certified fire door, stop before the first pilot hole. Call a joiner when a screw has sheared in a frame you cannot afford to split, or when the door is the only way out. The SAYAYO, the top pick, is a gate bar. It is not this bathroom sequence.

Common questions

How big a pilot hole?
Use a pilot of about 2–3 mm, roughly 5 mm deep, because the screws are small. Drill one hole, fix it loosely, then level the body and drill the rest. A full-speed drill with no pilot is how heads shear on the soft screws in several of these packs. The silver JelKen listing states six screws and a 4 mm mount hole. The necked chrome barrel’s screw count is not stated.
How do I mark the keep?
Throw the shoot fully, hold the keep over it, and mark through the keep’s holes while the bolt is engaged. Leave a little clearance so the shoot is not jammed against the far side. If it binds on the first test, move the keep before you alter the bolt. Marking with the bolt withdrawn is a guess, and the guess is what binds later.
What if the architrave sticks out?
Chisel a shallow recess so the keep sits in line with the shoot. Do not bend the bolt to hop over the moulding. A bent or cast shoot is close to the snapped-body failure reviewers describe on a light chrome bolt. Chisel only the timber that is actually in the way, and test the throw after each pass.
The bolt sticks. Is it the bolt or the timber?
Often it is the keep, set too tight, or the door swelling in damp weather. Move the keep or ease the hole, and throw the bolt again. A stuck bathroom bolt with no outside release is the cautionary case in this set. Replace the bolt if the body has cracked. Oil hides a keep that is a millimetre out until the next damp week.
The screw head snapped. What then?
Stop driving it. If you can back the stump out without splitting the stile, fit a sounder screw into a fresh 2–3 mm pilot. If the stump will split the frame, leave it and get a joiner. Several alloy and chrome reviews in this set lost screw heads. The supplied pack is not a promise.

Related pages

Best door bolt

Door bolt

Barrel bolt or mortice bolt: when to leave the set

Door bolt buying guide: type, length and the metal

Shed door bolt: padbolt, or two hasps and padlocks

Sources

Public UK sources from the research digest, used for this page in October 2026. Prices, stars and review counts are the amazon.co.uk figures on the twelve listings. No BS EN 12051 grade is claimed, because none of the listings prints the code.

  1. DHF: bolts to BS EN 12051:2000 (retrieved October 2026)
  2. Secured by Design: locks and associated hardware (retrieved October 2026)
  3. ProtectUK: security at home (retrieved October 2026)
  4. Secured by Design: secure sheds and outbuildings (retrieved October 2026)
  5. IronmongeryDirect: which type of door bolt (retrieved October 2026)
  6. The Crime Prevention Website: other door locks and bolts (retrieved October 2026)
  7. DHF: requirements for escape doors (retrieved October 2026)
  8. Master Locksmiths Association: minimum security requirements, January 2025 (retrieved October 2026)