Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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Autocannon Book   General Military Discussion

Started 21/4/21 by Barnowlgreen; 17424 views.

From: roguetechie


Tony, does the book cover the colt cr26 at all?

You know me I'm always on the lookout for anything I can get on Russell s Robinson and his work.


From: autogun


roguetechie said:

ony, does the book cover the colt cr26 at all? You know me I'm always on the lookout for anything I can get on Russell s Robinson and his work.

Yes, although I don't think that there will be anything that is new to you (sorry about the small font, it's the best I can do):

26MM COLT CR-26: 26 × 130 AMMUNITION.

Russell Robinson was a prolific Australian gun and ammunition designer most noted for a range of Constant Reaction guns which utilized floating firing, or differential recoil, to spread out the recoil impulses and make automatic weapons much more controllable. His work was nearly all focused on small arms of up to .50 calibre but he did design one cannon: the CR-26.

The CR-26 was developed in the late 1960s while Robinson was working at Colt and was intended (to quote from the brochure) to offer 30mm levels of performance with the dimensions and weight of a 20mm gun, and the trun- nion reaction (maximum recoil thrust) of a 0.50-inch MG. It was designed to be suitable for vehicle mounting, particularly in turrets, and featured recoil operation, delayed extraction and forward ejection in order to minimize the escape of gun gas from the breech. It would have been an interesting competitor in the Bushmaster programme, but by the time that reached the trial stage Robinson had left Colt and there was no-one to continue the development of the gun, of which only two were made.

The bare gun weighed 47kg, and 54kg complete with selectable dual feeder, power and manual chargers, and power and manual triggers. It was 201cm long with an L/64 barrel, and fired at 550rpm. The barrel reciprocated through 11.4cm; as the gun fired when the barrel was travelling forwards, this was said to be equivalent to 45cm long recoil when firing from rest. The peak trunnion reaction was stated to be less than 450kg.

(And the ammo):

26 × 130 COLT CR-26

This was a late 1960s project for a light AFV gun (the CR standing for Constant Reaction, a reference to the low-recoil operating mechanism), a role eventually filled by the Bushmaster M242 in 25 × 137. The greenish lacquered steel cases were made at Altdorf, the Swiss government ammunition factory, which Colt loaded with various projectiles for testing; aluminium alloy cases were also made, by General Impact Extrusion Ltd. of Canada. Two service loadings were developed: an HE weighing 195g (including 28g HE filler) and fired at 945m/s; and an APFSDS-T weighing 112g at 1,265m/s (penetrator weight 65g). Both had a maximum chamber pressure (piezo) of 345 MPa.

The AP projectile is often quoted as APDS but this is misleading; in the US at this time it was not unusual to refer to APFSDS as APDS. The stated penetrator length of 130mm and diameter of 6.35mm – an L/D ratio of 20:1 – clearly means this was APFSDS. Another APFSDS version examined had a length of 152mm and a diameter of 5.5mm, giving an L/D ratio of 27.5:1. Fin stabilisation was used, but the projectile was also spun by the rifling at 1,360 rps (1,040 rps for the HE-T). Penetration was stated to be 26.7mm/2,000m/60 degrees. Overall round length is 185mm and the weight of the APFSDS-T round is 258g with an aluminium alloy case and 380g with a drawn steel case: weights of the HE-T are 328g and 449g respectively.


From: roguetechie


You are correct that it's nothing I don't already know but I am glad you are covering the cr26 in your book.

The cr26 is a design that was if anything ahead of it's time and deserves another look now.

Due to the persistent and constant drone threat we will be facing in future conflict a gun like the cr26 could actually be an extremely viable way to give ground vehicles protection at low cost.

In reply toRe: msg 38

From: autogun


I have heard from Crowood that the book is now on sale.


From: Barnowlgreen


just got mine from Crowood today! It's a larger format book than Rapid Fire, I thought it would be the same size. A lot more colour phtos, I like the pictures of all the cartridges together on each calibre page. The tables seam similar to Raid Fire but the guns are not grouped by country but by calibre. The only problem I can see is that a couple of the pictures are rather blurry, but finding clear pictures of all guns and cartridges must be diffacult . All in all my first inpression is a  nice addition to my libary.


From: autogun


Thanks for the comment.

There were two images which disappointed me for lack of clarity, although for one of them there is another pic later in the book which is OK. Given the international nature of the production, with various firms involved in addition to Crowood in dealing with the layout, design, printing etc, communications were somewhat complex but despite this I think the end result has turned out well.

I should point out for the benefit of potential purchasers that it is only the cannon table which has the guns in calibre order: the text  (the bulk of the book) is organised by nationality, then within that by approximate date of introduction. There is also an introductory section for each nationality which talks about the companies involved, designation systems etc.