Talk:GC-45 howitzer

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There's a lot of errors of detail and exaggeration in this item.

Eg the footnoted ref to the importance of GC-45 in the Gulf War, Iraq had a lot of artillery, most of it of Soviet origin, with a few from other countries including France. GC-45 was just a small part of this arty array.

39 cal 155 is not a NATO standard. NATO agreed to use 155mm. In 1963 4 member nations agreed to a ballistic MoU that gave a specification for a 39 cal barrel. First users were M109A1 (different to M109), M198 and FH70.

Ref to accuarcy of GC-45 being as good as M109 but at far longer ranges. Accuracy has little to do with gun design, its actually about the ballistic model and data used to compute firing data. Consistency/dispersion is another matter all together. —Preceding unsigned comment added by Nfe (talk • contribs) 03:51, 23 October 2007 (UTC)

I spent aa quiet 10 minutes today examining a towed 155mm, the original plates on it gave the designation "GN C 45". Unfortunately I didn't have a tape measure so couldn't measure the barrel length, also all serial numbers had been scraped from the plates.

However, this gun had: No auxiliary engine and nothing to suggest it had ever been fitted with one. A rifled barrel. A breech that looked like a direct copy of M109.

It was nowhere near as sophisticated as FH70 (I examined one of these last month), all in all a very ordinary gun, I'd describe it as the sort of thing done in the 1950s.

I understand this gun came from Iraq in 1991.Nfe (talk) 07:33, 18 November 2007 (UTC)

Good work there! I'm not sure if we can include information you measured off an actual GC-45, though, since it's difficult to verify. However, any published sources you can find for the information would be very, very welcome, since this article seems to need them. <eleland/talkedits> 17:11, 18 November 2007 (UTC)
If he can photograph himself using the measuring tool on the GC-45 (and upload it here), then it'd be a primary source but it can be valid because it requires no specialist knowledge to verify --Kazuaki Shimazaki (talk) 02:05, 24 November 2007 (UTC)
FYi, the G5 is rifled - see [1] Socrates2008 (talk) 02:31, 24 November 2007 (UTC)

I'm not sure I understand the debate about the rifling here: of course they are rifled, the issue is how they are rifled. The G5 is "reverse rifled" compared to a conventional non-ERFB gun. Scroll down in quoted source (above) and look at the ammunition. You can see the "driving keys" quite clearly on the ammo. These fit into the slots in the barrel. Nor does the article imply that the gun is not rifled, on the contrary it states very clearly "...boring out the barrel to a smoothbore, cutting the new rifling into it...".

Furthermore, the accuracy of the GCN-45 is not a side effect of the gun, but the ammunition and powder. Again, the article states this pretty clearly. The lower supersonic drag means that winds and other atmospheric effects have that much less effect on the trajectory, and because of the long flight times (and distances), ERFB rounds tend to drop almost vertically on their targets (check out images on the 'net of the M777, for instance). The quoted reference has the numbers, you can compare them with the M109 at your leisure.

Finally, the 155/39 is the defacto NATO standard. Older US, Canadian, Belgian, French, German and UK systems were all based on the same ammunition and loads developed for the M109 or M198, representing almost all of the 155 artillery in NATO service. While it is true that these systems are all in the process of being replaced, that's also something the article states pretty clearly.

Maury (talk) 19:08, 26 January 2008 (UTC)

Having peered up the barrel and knowing what I was looking at I can safely say that the rifling is entirely conventional, although without looking at the gun handbook I couldn't say what shape of groove was used but that's a very esoteric detail will minimal effect (its mainly to do with loading on the lands to prevent them stripping). Like any other other rifled barrel it has grooves and lands, and these were similar in size to other guns (you'd need good instruments to measure any differences). The lands and groove impart spin to the projectile via the driving band, which also provides a seal to prevent charge gases seeping around the shell as it moves up the barrel, it also holds the shell in position when it has been rammed so that it doesn't slide back before it is fired.

What the EFRB shells do have are nubs on the ogive, these are necessary to stop the shell wobbling as it goes up the barrel. They are a consequence of the highly sreamlined shell shape. Normal shells don't have them. These nubs have nothing to do with rotating the shell as it moves up the barrel. Reference to boring out a 155mm barrel then cutting new grooves is nonsense, for starters it would no longer be 155mm (and 155mm isn't 6 inches either).

Talk of all 155mm having the same 'loads' as M198 or M109 is twaddle. The US system of Green, White and Red bags is totally different to that used by GE, IT, UK with FH70, which uses a completely different charge system with triple base propellant. AS90 also uses this. Incidentally the first 155mm ever developed by UK was AS90, I don't think Canada has ever developed one either.

Drag has nothing much to do with wind, and the effect of head wind is relatively small. Cross wind is a bit greater because it has a larger area to work on. Ammunition design doesn't have much effect (if any) on accuracy although quality control in manufacture does, if the projectile is slightly different to the standard for which the data compiled then self evidently the shell won't go where it was aimed. That said wind, temperature, shell weight and other factors are all taken into account when computing firing data. As I previously said accuracy is a function of the ballistic model and the quality of data, both the basic aeroballistic data and the data for conditions of the moment.

Can't see how shell shape can have any affect on angle of descent. This is basically determined by angle of departure, but is steeper basically due to the accumulative effect of air resistance (in vacuo a shell has a completely symetrical trajectory). It might be argued that other things being equal a more streamlined shell has a less steep angle of descent because air resistance is less (but I don't think other things can be equal).

Incidentally the article is supposed to be about the gun. The EFRB ammo can probably be used with any 155mm. It's just that most western armies are supported by competant scientists to cut thru the BS and have decided that EFRB shells aren't worth the bother, basically due to their inherent payload capacity limitations. Nfe (talk) 12:10, 27 January 2008 (UTC)

"Talk of all 155mm having the same 'loads' as M198 or M109 is twaddle"
I stated: "Finally, the 155/39 is the defacto NATO standard". Every force in NATO deploying a 155 was deploying a 155/39, either using the US M109/110/198 directly, or alternately locally-designed weapons that were firing the same rounds. The only outlier was the FH-70, which allowed for higher loadings. But none of these came close to the loadings of the GC-45. This shouldn't be surprising, given the increased caliber, larger breech and dramatically strengthened carriage (and 3500 kg higher weight).
"Can't see how shell shape can have any affect on angle of descent"
I stated: "because of the long flight times (and distances), ERFB rounds tend to drop almost vertically on their targets". I see no reference to shell shaping in this context.
"Drag has nothing much to do with wind"
I stated" "that winds and other atmospheric effects have that much less effect on the trajectory". I don't see anything about the wind being the cause of drag here.
"The EFRB ammo can probably be used with any 155mm."
Depends on what you mean by "The EFRB ammo".
If you mean "The EFRB ammo" for the GC-45, the answer is "no". The same is true for the 155/45's from Austria, China and South Africa.
If you mean "The EFRB ammo" that has been developed in the last couple of years, the answer is "maybe".
Let me illustrate the difference. This document shows a number of "classic" ERFB rounds, whereas this one shows their newer designs that are built to the post-JBMoU design. The differences are painfully obvious. Note, for instance, that the former has the keys that ride in the rifling, while the later does not. Also note that the ERFB rounds are almost 20 cm longer than a M107, they won't even fit in the same breech.
So be sure to be precise, because, as you said, were talking about a specific gun here.
"thru the BS and have decided that EFRB shells aren't worth the bother"
I'd love to see your explanation as to why every single new artillery piece in the western world was specifically designed to fire ESFB, and even those from SA and China. You'll also have to explain the "NATO Joint Ballistic Memorandum of Understanding" on the topic of the newly-shaped M549. And the upgrades to fire control systems, C&C, tacom etc, that have been deployed over the last couple of years to support it. And the massive buys of new rounds based on ERFB design. And the attachment of drone units to RT, and and and and...
But, as Mr. Sparkle's owner once said, "don't be-reve me", here's a nice overview from the right time frame. Here's some key quotes:
"the revised bourrelet outline (that is, the nose shape) renders it fully compatible with Nato standard requirements (the original ERFBs were not)."
"conventional gunners pointed to ERFB manufacturing and handling difficulties and to the long and heavy barrels (and carriages) that had to be used to gain maximum advantage from the ERFB..."
"Target acquisition at such ranges, once a major argument against the immediate procurement of ERFB..."
"basically due to their inherent payload capacity limitations"
Where did you possibly come up with this claim? ERFB rounds have more explosive load, because they're longer than a similar non-ERFB round. Consider the standard US round at the time, the M107. The M107 had an explosive load of either 6.985 kg with RDX or 6.62 kg of TNT. Denel's standard ERFB-BB round from the 155/52 has 8.8 kg of PBX. If you do the math, you'll note that it's a 25% improvement in explosive loading, while at the same time doubling range and keeping or bettering the accuracy. Comparisons with standard Soviet 152's (D-20 or 2S3) are even more favorable. This is why ERFB is considered such a revolution in artillery design, and Bull is considered one of the greatest artillery designers in history.
Maury (talk) 16:23, 27 January 2008 (UTC)