This is somewhat true – some manufacturers do forge rifling and chambers with one mandrel, in one process. Others forge the rifling and then ream the chamber as a separate process, much like it would be done after cut or button rifling processes. I have observed seven hammer forges in operation, and discussed the pros and cons of both methods with a number of gunsmiths, engineers, technicians, and machinists in the United States and Europe.
Companies like Beretta value the hammer forged chamber and rifling because it eliminates the inconsistencies – both in the “length” of the chamber and the alignment of the chamber with the rifling, which can suffer based on the quality of the employee performing the work – that result from performing the process separately. That said, they don’t use this one-step process for every barrel they make.
On the other hand, Steyr, which has been hammer forging barrels longer than any other company, reams chambers in a separate process, in part because there can be issues with the way the barrel steel “flows” around the neck of the chamber, negatively affecting accuracy. Steyr’s focus is on precision, and employees take their time ensuring that each barrel has been forged exactly right, and each chamber has been reamed – and then polished by hand – correctly.
http://www.luckygunner.com/labs/5-56-vs-223/
-------
Вопрос на самом деле очень интересный.
Несмотря на то,что теория говорит нам о соосности канала и патронника при ковке, Штейр нарезает свои патронники доп. операцией после ковки.
На винтовках модели Сако ТРГ, патронники нарезаются также дополнительной операцией.
Связано ли это с переключением режимов ковочной машины или еще с какими то факторами - непонятно.
Вполне может быть,что один из тех случаев, когда теория и практика противоречат друг другу.
