Locking Bolt

[Gary Laudermilch]

I am aware that Parker Bros. made a design change in 1911, I believe, that added a hardened locking insert. I believe I've also seen that they retrofitted guns returned for service to the new design at no charge.

Obviously, the company realized or thought they had a problem with the original design. Just wondering how much of a problem the original design really was. Since many of you are using guns that predate the change, how many are experiencing worn locking bolt bites? Have any of you retrofitted older guns to the new design? Is the locking bolt itself different? Etc. etc.

Just trying to learn something on this subject so your thoughts would be appreciated.

[Bruce Day]

Mr Laudermilch, Parker called this a bolting system comprised of the bolt and matching bolt plate.

The system is discussed in The Parker Gun catalog circa 1934 ( Skilled Hands catalog) and in The Parker Story.

For my personal experience, I have guns with the pre 1910 bolt system and the post 1910 system . I can see no practical difference, although it is a more interesting design. I do think the 1905 r & r pinned, completely tapered bolt plate was a superior design to the previous lug bite but I personally believe that if the bolt/bite connection is kept lubricated and the lever is held open upon closing and eased closed, the lock is unlikely to ever wear out. There are many pre 1905 Parkers that have had many rounds through them and are still tight and lever centered today.

The pinned bolt plate when replaced must be individually fitted to the gun. This is true for either the fully tapered 1905 or the stepped 1910 versions.

[B. Dudley]

In 1905 they added a hardened wear plate. Then in 1910 the whole bolting system was redesigned in order to reduce parts and at that time a hardened wear plate of a different design (stepped) was used. This design was used until the end of Parker production.

The original design of bolting does wear over time. The tapered bolt design is good, but does not hold up over time as well as two hardened surfaces used for bolting. That is why the 1905 design was implemented so that a hardened and replaceable insert was being used. The 1905 design however used more of a straight bolt design.

The stepped 1910 design combines the benefits of all 3 into one. A tapered bolting surface, a straight surface and a hardened replaceable piece.

[Bill Murphy]

Are any of the bolts compatible with barrels with a different bolting surface?

[Kensal Rise]

Another rationale/benefit of the insert approach was production speed. It took a lot less time to fit up a bite with this system. And time is money when you're making products. The replaceable bite also made later servicing the system faster... and cheaper.

The major culprits in bite/locking bolt interface degradation are poor lubrication of the surfaces, improper cleaning, and heavily loaded cartridges. Just to name a few.

[Autumn Daze]

The bolt design from the introduction of the hammer less gun in 1888 featured a 12 1/2 degree angle for locking. This did not change over the course of production. The design changes with the replaceable bite and later the stepped bite were to allow the parts to be fitted and repaired faster.

[B. Dudley]

Dave,
Actually, the 1905 -1910 wear plate did result in more of a straight bolt setup.

Manufacturing costs might have been higher to use the wear plate since there was the wear plate to manufacture, along with additional operations on the barrels themselves to fit them. But service was made easier no doubt.

[Bill Murphy]

What about compatibility between one type of barrel and another type of locking lug?

[B. Dudley]

Post 1910 barrels can be used on pre 1905 guns. Not visa versa.

[Autumn Daze]

Brian, reread what I posted. I was speaking of the locking angle. Anything under 15 degrees is a locking/ compensating taper