By Kent · Lock Depot Staff Writer

Same price, same core, three different doors

KSP prices its 6/7 pin housings the same across the mortise, rim and tapered head styles. With the price flat, the only way to get this wrong is to buy the shape that does not fit the door. It happens, because the three look alike in a catalog row and nothing like each other in a lock.

All three are sold less core. You supply the core. This article is about the housing, which is the body the core sits in and the part that has to match the lock.

The 307: the mortise housing

The 307 is the one most people mean when they say mortise cylinder. The 307-600-03 is a 1-3/8" mortise housing with a standard straight cam in bright brass. The same body comes in satin brass, satin bronze, oil rubbed bronze, bright chrome and satin chrome.

A mortise cylinder screws into a mortise lock body or a storefront lock, and it has a thread on the outside of the housing. You turn it in from the face of the door until the cam lines up with the lock. A set screw or a cylinder retainer holds it there.

Use it when the old cylinder was a threaded, round, barrel-style cylinder, and when the lock was built to take one. That covers mortise locksets and storefront deadbolts. The cam choices are covered in a separate piece, which compares standard, Adams Rite and the two named clover cams.

It also comes in 1-3/4" long. If the door is thick or has a heavy face plate, the length decides it. Measure the old cylinder, not the door.

The 306: when 1-3/8 is too long

The 306-600-04 is the shorter cousin, a 1-1/4" six pin mortise housing in satin brass. It is the same idea at a smaller length. I would not stock it until a customer asks, because the length is the only reason to want it. Where a 1-3/8" housing would stick out past the face, this is the part.

The 308: the rim housing

The 308-26D is the rim housing, listed as a 6/7 pin rim housing less core in satin chrome. It comes in bright brass, satin brass, satin bronze, oil rubbed bronze, bright chrome and satin chrome.

A rim cylinder sits on the surface of the door. It goes in through a hole bored in the door from the front, and it connects to a lock or exit device mounted on the inside face. You see this on night latches, rim exit devices and a lot of older residential and light commercial doors. We have written up the night latch case in the Ilco rim cylinder article.

The listing for the 308 does not name a cam. That is normal for a rim cylinder, which does its work through a tailpiece rather than a cam on a mortise body. If you are replacing one, look at what drives the lock. A rim housing with the wrong tailpiece length or shape will turn and do nothing. The listing does not give me the tailpiece, so I will not claim one. Check the old cylinder.

The 317: the tapered head

The 317-600-26D is listed as a tapered head housing with a standard cam in satin chrome. There is an Adams Rite cam version too, in satin brass, satin bronze, oil rubbed bronze and satin chrome. There is no clover cam in the 317 family.

The name says the shape: the head of the housing, the part you see from the face, is tapered. I do not have a dimension drawing in the listing, so I am not going to give you an angle. The way to buy a tapered head is old for new. Hold the face of the cylinder you pulled next to the 317. If the shapes match, it is the right part. If they do not, it is the wrong style.

Do not substitute a different head shape because the thread and length match. The head is part of the fit.

Side by side

Housing	Style	Length or detail	Cam in listing	Where it goes
306	Mortise, 6 pin	1-1/4"	Standard	Where 1-3/8" is too long
307	Mortise	1-3/8" (1-3/4" long)	Standard, Adams Rite, clover	Mortise locks, storefront
308	Rim	Less core	Not listed	Night latch, rim device
317	Tapered head	Less core	Standard, Adams Rite	Match the old cylinder face

The core is the same decision for all three

Whichever housing you choose, the core is a separate purchase, and the keyway decides whether the new cylinder joins an existing master key system. We covered the KSP core and how it compares to a Best keyway in the KSP SFIC core article. If you are comparing against another interchangeable housing, the Arrow 16CR and 16CRT article covers a similar fork.

The listing says 6/7 pin. I do not have the exact core format spelled out for the housing, so confirm that with us before you order cores in bulk.

Mistakes I see

Buying by finish first. All three come in satin chrome and it is easy to pick the housing that looks right in the photo.

Using a mortise housing where the lock needs a rim cylinder, and finding out when the thread does not stop where the lock expects.

Treating a tapered head as a trim option. It is a fit detail.

Ordering ten housings before checking one. Order one, try it in the door, then place the run.

Common questions

Does any of these include a core?

No. All are sold less core.

Which has the most cam options?

The 307, with standard, Adams Rite, clover, and clover named for Schlage L and Sargent.

Can I swap a rim housing for a mortise one?

No. They mount differently and drive the lock differently. Match the style to the lock.

Are they the same price?

Yes. The listings I checked carry one price across all four.

The full run is on our KSP page. Send us a photo of the old cylinder from both sides and we will pick the housing.