XM 179 US Self-propelled gun

uk 75

ACCESS: Above Top Secret
Senior Member
27 September 2006
Reaction score
Some time ago I was chasing up info on a US self-propelled gun.

I have now been able to confirm in a couple of books published
in the 70s that the XM179 SP gun to replace M109 was cancelled
by 1976. It seems likely that the system was too similar to the
M109 A1/2 to make it worth pursuing, but no pictures exist.

One possibility is that the US were planning a vehicle similar to the
abortive European SP70 (mounted on a Leopard tank hull), perhaps
on the MBT70/XM803 chassis. This project had also collapsed by 1976
in favour of the wholly new XM1(later M1 Abrams).

Maybe someone in the States knows more....

UK 75
Unfortunately UK 75, I see nobody had replied to this XM 179 SPG request :'(
Pity, as I'm very interested, and have attempted in vain to find anything on it :mad:


Thanks for replying. I have also had no luck. My best guess is that the XM 179 was simply an M109 variant dropped in favour of the development of M109 A1. Alternatively it might have been part of a family of vehicles based on the M107/M110 chassis like the unsuccessful XM 701 MICV.

It does seem odd that nothing more is known...

UK 75
Actualy there is a 155mm Self-propelled gun based on the M107/M110 chassis.


  • 1.jpg
    74.8 KB · Views: 1,330

According to page 1 of the above, XM179 was a short lived program from 1968-1969 replacing the unarmored XM134 design, before being canceled in turn as too complicated. All effort was then focused on the XM198 towed gun. This was all part of the US Army effort to field howitzers and ammunition that met the early 60s NATO standard for 30km range field artillery that was much delayed by focus on air mobility and new 105mm designs.

Given that the M109A1 came out in 1973, it seems very likely that it was the alternative to XM179, though I believe it took until the M109A2 to get a cannon good enough to actually meet the 30km requirement with rocket assist.

The single prototype T245 (at least that is what Roco Minitanks called it) was a one off prototype in the late 50s at the same time as the later M107 and M110. I was thinking more in terms of the lighter gun used on the XM 134/Xm138.

Sea Skimmer

Thanks for the item below which seems to very much pin the project down and also explains the lack of much info and pics of XM 179
Hunnicutt's Sheridan identifies it as T245. It seems to have only been a bit of a hedge against failure of the 175mm, because at the time two 175mm gun and three 8in howitzer prototypes were ordered on the hull, against only a single T245 with 155mm gun. This was in 1956.

Meanwhile back in 1950 the US Army had already decided that 155mm corps guns would be replaced with 175mm guns in the future following a long experience in WW2 being outranged by German 170mm guns, which largely defeated the purpose of the 155mm gun as the main corps counter battery weapon.

Originally the 175mm was going to go on a Patton hull and considerable work was done on this, but it turned out too heavy to be satisfactory, and by the mid 1950s the US was in one of those air mobility crazy periods anyway. The T235 prototype with 175mm weighed 59,200lb against 54,800lb for the T245 so the latter had little advantage. It was formally dropped in 1959 and never converted to diesel power as the other two desgisn were. Limited production of the M107 and M110 as we know them was contracted June 1961.

If you are wondering and since I already have it open, the 175mm Patton was similar to the M53 and M55, but the Patton hull was much modified including being widened, designated T162. It was canceled as too big around the time work began on the projects above. Weight was 107,000lb stowed for combat. 15 rounds of ammo carried, some armor slightly thinner then M53/55 to reduce weight. Three pilot models were built; someone has a nice picture of one below.
Thanks for the heads up re the 155mm T245 Xiaofan!!
The 155mm ordinance looks to be a simple adaption of the M1/M2 (M59) Long Tom to the chassis of the M107/M110

Thanks for sharing

Just found this in my file. May be colse to what you want. It looks like a 155mm ordinance on a light chassis.


  • 1.jpg
    53 KB · Views: 996

Thanks for finding this one. It looks at first sight very like the XM134 illustrated in Hunnicut but it is a new photo, and a weird colour too.

It is interesting to see the clash between the airmobile requirement for a light gun and chassis and the Central European Front requirement for an NBC protected crew compartment. The requirement for a lighter mechanised 155mm gun re-emerged after the Cold war with a number of designs proposed but not adopted in the US and elsewhere.

UK 75
Sea Skimmer said:
Given that the M109A1 came out in 1973, it seems very likely that it was the alternative to XM179, though I believe it took until the M109A2 to get a cannon good enough to actually meet the 30km requirement with rocket assist.

IIRC there was no difference between the ordnance (ie barrel assy to USpearkers) used with A1 and A2, both conformed the 155mm ballistic MoU, A1 was retrofitted 39 cal barrels, A2 was new build guns with 39 cal barrels.
Now and again I bring up the mysterious XM179 replacement SP gun for the M109. It was around between 1968 and 9 before being cancelled.
No description or artwork has emerged in any source
I'd also be interested in more details on the XM179 programme.

According to Report Number: CAL-GM-2600-H-l-VOL-l, Publish Date: 19680701, the XM179 was to have been "available in the 1970-1980 time frame" ... which seems awfully vague. At the time of the report, data was being drawn from nine different "government-provided concepts and four reference weapon/vehicles". So, obviously, no XM179 requirement ever got issued to industry.

The report does have one detail: "the XM 179 concept recommended for engineering development is a weapon/vehicle system that utilizes a composite armor to provide ballistic protection for the crew." So at least there's a hint of the preferred armour type.

Anyway, the whole XM179 programme only seems to have lasted for a year and a half. The lightweight XM138 was cancelled in mid-1968 so that funding could be transferred to the XM179. The final version of that report was issued until 21 July 1968. But, anticipated costs led to the XM179 being cancelled in December 1969 (although some US government sources say November 1969). Work then concentrated on the XM198 Towed Howitzer.
I remember the 155mm XM138 and the 105mm XM104 lightweight unprotected sp guns getting chopped.
Presumably with a live war in Vietnam and Cold War in Europe, there was no longer money for such imaginative but fragile weapons

Similar threads

Top Bottom