c-g-designs

THOUGHTS ON A ULTRA-LIGHT RIFLE ACTIO N CONCEPT.

The subject ‘Lightweight Action’ is often evoked on forums, but very few solutions are proposed.

All suggestions concern  only the realisation of a Titanium receiver and lightening the botlt  by fluting its body . The creation of flutes might look fancy, but could create splitting starting points as reducing the bolt body setion between bottom of flutes and bolt bore diameter. I will not enumerate again the list  of positives and negatives on the use of Ta6V grade 5 alloy for receivers making. This has been developped often on forums. I will simply say I do not consider this metal as  really suitable for the task.

Other approaches could be considered. I think here of the light metal alloy 7075 T6 who, effectively, would allow the most important weight reduction if used for receivers.

Also,a bigger weight saving could be realised for the bolt in lightening the  bolt body from the inside, increasing the bore diameters, instead as fluting the outside, this creating possible split starts if grooves made too deep. Out of fancy, fluting only achieve reduced weight gains.

            As for the receiver, lets consider the respective density of the materials :   ---Alloy steel = 7,8.                                                                                                              ---Titanium = 4,6, or still 60% of those of the steel.                                                          ---Light metal 7075 = 2,8, or 35% of those of the steel.

            One can then conclude that, dimensions being equal, the use of light metal allow a considerable reduction of the receiver mass.

            The 35% hereover would not be absolute as the necessary hardened steel inserts would slightly increase this percentage. We  can by former experience consider this to be 38%, maximum 40 %. This remaining still far inferior to the titanium one, and moreover the use of heat treated steel inserts for critical functions allow wear and strenght resistance that titanium does not allow.

            The bolt can be  sensibly lightened, not only the bolt body by bore diameters increase, but also by reduction of the percussion moving parts  mass by the adoption of a different percussion system. I have here a bolt body made time ago for a similar concept who wheight only 181 grammes (this would be250-260grammes for the  completely assembled bolt).

            Taking as a model the Remington 700 Short Action :                                                 ---Receiver weight with C.G trigger = 470 grammes .                                         ---Bolt weight = 354 grammes.                                                                                 ---Action complete = 824 grammes(29,4oz)                                                            

            But a light metal action of same dimensions  could weight :                                                                    ---Receiver = 470 x 0,40 = 188  grammes .                                                                    ---Bolt estimate = 280 grammes.                                                                                     ---Total  estimated weight = 468grammes(maximum 500grammes), or 16,7 to 17,85oz).

            A more important weight reduction could consist in sensibly  shortening the overall lenght to adopopt shorter cartridges of the .223 lenght, using AR 5 or 10 shots magazines . This would create a mini-action systen and allow a lenght reduction from an OAL 200mm of the Remington 700SA  to some 180mm, resulting in a more 10% weight reduction, or a total weight of  no more than 450 grammes (16oz).

            For this, one should accept to no longer consider the .308 basis lenght, and use  calibers such as the 6,5-7mm  Grendel or the 7,62x39 and derivates, as well as the.223 and its derivates.

            If used as single shot, the shortened mini action would still accept the 6mmBR Norma round .

            To note also that a shortened bottom metal/trigger guard would also assist in weight saving.

All the ingredients exist for both SA and Mini options  and have proven their value for such a realisation. But such a project would it be viable ??.  Also, for the shorter version, the calibres available might not be considered as sufficiently powerfull ??.

10/2016

R.G.C