Reducing number of No.4 Barrel grooves to speed production?

[chanman]

This was bugging me. Weren't No.4 barrels broach cut with all the grooves cut all at once?

Does the time savings come from simply having to remove less material per barrel, or does the time savings come from saving time making the broaches?

Information

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[Bruce_in_Oz]

Useful article here:

Firearms History, Technology Development: Rifling: Manufacturing: Broach Rifling

Broaching requires a serious upgrade in machinery from the basic “single-tooth” cutter method.

Once up and running, the production rate is quite high; the complex tool travels through the bore ONCE and the rifling is finished.

The other contender is cold (hammer) forging, as developed by out Teutonic cousins. They had to come up with a production technique that could keep up with their consumption of machine-gun barrels. When you have a fleet of thousands of MG-34 and MG-42 (and several other) guns at “work”, the demand for replacement barrels is ferocious.

The only fly in that ointment is the supply of suitable materials and machinery to make the mandrels and the rotary-hammer machines themselves.

The US used broach-cutting for some production; one notable product was all of the National Match M-14 barrels.

They also used a LOT of “traditional” machines.

Meanwhile, also in the US, another method arose: “buttoning”. The idea dates back to the late 19th century. However, it languished until the engineers at Remington refined it in the early 1940s

[chanman]

Does that mean that all Enfield barrels single-point cut then?

[Bruce_in_Oz]

If they were using machinery built to make SMLE barrels, quite possibly.

If you have a shed full of "single-tooth" cutting machines, you can turn out a lot of barrels each day.

A shed full of machines hauling broaches will rifle a LOT more, though.

Part of the reason for the "two-groove" barrel was to greatly reduce machine time per barrel whilst using "conventional" cutters. Broaching a two-groove barrel would likewise involve a slightly "less-expensive" tool`

Certainly, SMLE barrels of pretty much any denomination were rifled with "single-tooth" cutters; as for what happened in WW2 with No4 barrels? I don't have that paperwork.

[Peter Laidler]

Single tooth cutters - using a lot of machines!

[bigduke6]

The article in the link below I,ve always found it to be an excellent read and look at the picture of the P & W sine bar rifling machine made in 1885.......

The Making of a Rifled Barrel, FirearmsID.com

[Simon P]

There one for sale at the moment for £15K

[Mk VII]

The list of machining operations I have here from Savage says:
Operation Sequence No.27
operation #32A - rifle on Builders Rifling Machine
type of tools:- ET-6 rifling head ET-6A wedge ET-6B wedge ET-6C wedge ET-250 hook cutter ET-287 shank
Standard time for 100 Pcs 11.046

[bigduke6]

There one for sale at the moment for £15K

Any more info Simon ?

[Simon P]

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