Spike Rifles: Not Shiny Enough.

[BaxterRicketts]

Well, I do not know how to start this, so I'll just kick down the door.
I have never, once, seen or even heard of anyone using termagants with spike rifles. It seems to be either thereliable Fleshborer that we all know and love, or the Devourer-armed hell raiser that apparently is loved like that kid down the street who can do literally everything better than you. And yet people seem to love to slam the spike rifle. Now, I agree, it could be better. There are very good arguments for why it should be a free upgrade. Now, without resorting to math-hammer (which probably hurts it more), lets look at the pros.
A warning now, this will be long and probably boring.
1) It is range 18". In a game of mobility, 6" can mean a lot, so congratulations, Termagants, you now have weapons with a range that is on the average of the rest of the swarm.
2) It is only an extra point. Therefore, you do not have to break the bank on the little guys, because ultimately, it is only 6 points. Get over it,remove a genestealer or two and move on.
3) Surprise & Ignorance. Never heard of anyone using Spike rifles? So has your opponent. He/she won't be entirely sure how to treat them, and you probably won't either. So think up something new! FSM forbid that you have to be put in a new situation!
Oh...now I see there are less pros than I initially thought...But still, lets see what these mean.
Spike rifles on our gaunts means they can do multi-task. Instead of hiding on objectives and acting as meatshields to be thrown as hard as possible, they can now sit on your objectives and shoot the enemy.
If you are facing an army that even tyranids want to shoot a bit first (A nasty Ork horde I sometimes play springs to mind), you can sit in your cover, and shoot them sooner. The shooting may be less effective overall, but I'll take my shots sooner than later(especially if I might never even get to fire at all).
This extra 6" of range means your threat radius became 24". This can be big, especially if (as see above) you are not big on getting into combat right away, yet still looking to put pressure on your opponent. Combined with warriors, you could move your Gaunt-wall, shoot with your Warriors and then pound the same unit with the Gaunts. Granted, because of this you may get shot an extra turn, but they are just gaunts. Speaking of that...
They are not pricey, nor obviously destructive like the devourer-gaunt. This means they are pretty much like the average termagant to your opponent. They won't draw fire any more than usual, and if you lose, say 10 in one turn, you have not just lost a load of your anti-infantry firepower. As they cost roughly 60% as compared to devourers, you can buy more.
Finally, just like Space Marines all die the same in the end, Gaunts, be they walking, running, or flying, die horribly. In short, 5 point termagants with fleshborers die just as much under fire or assault as 6 point spikerifle/spinefist gaunts or 10 point devourer gaunts. So unless you have one good turn of shooting, chances are your opponent will send them all to the dead pike without discrimination. So the more you can afford, the more you will probably have left at the end of each turn.
In closing, I am truly sorry this has gone on for so long. I know it wasn't the most glamorous subject. But if you have Tyranids, try out Spike Rifles for a few games. Even if they don't work out, at least you will know from practice, and not from what someone told you on the internet.

[newtoncain]

I've used them, not that good. 18" but 5's to wound MEQ

[Lemt]

30 Gaunts with spike rifles kill 1-2 MEQs with shooting, 4-5 Ork Boyz out of cover. With Fleshborers you kill 2-3 MEQs, 6-7 Or Boyz out of cover.
So the question would be, is it worth the 30 points?

[rocdocta]

no, not worth the points and the cost to build/buy the gaunts.

[Anggul]

S3 AP- with BS3. No thanks mate, I'll use gaunts for what they're meant for: popping off a few S4 shots and hurling themselves in with furious charge or poison from a Tervigon, or even let them assault me and the Tervigon will also give them counter-attack.

[Cavematt]

They're cheap for a reason. They make you think about fielding them, but they're not worth it. If you want the 18", pay more for the devourer. More range, more shots, more better.

[Tynskel]

They are a throwback to the days of lore. I am surprised they didn't make them AP 4. Really, they are there for folks like me that have old metal termagants with their spike rifles.

I like them, though. I use them on small units. Hunker down in cover. And start shooting. Typically the squad is outta synapse, just hiding shooting pot shots.

[Osiris]

Really, there's no reason to spike rifles. For +4 points over them you get +1S, +2 shots, and a Ld modifier on enemy units that take casualties. Or you can be a point cheaper and get +1S and an actual AP value for only -6" range. Hmm, I wonder why these are never taken...

[Inquiring M1nd]

Some quick mathhammer, since there is a massive points difference (as far and Nids are concerned) point to point is a strong way to look at these guys.
We'll go with a relevant points size that divides nicely: 144
Versus the typical opponent: Marine

Devourer: 16 gaunts: 48 shots, 24 hits, 12 wounds, 4 dead marines
Rifles: 24 gaunts: 24 shots, 12 hits, 4 wounds, 1.3 dead marines

Now, after a round of shooting, say... 9 marines

18 bolter shots, 9 hits, 6 dead gaunts

Devourer: 30 shots, 15 hits, 7.5 wounds, 2.5 dead marines
Rifles: 18 shots, 9 hits, 3 wounds, 1 dead marine

So, you have less power, though you can spread that power further around, making it harder to remove. You can expect to lose gaunts as you progress through the game. It's the same stats defending those points and weapon, I think the better question would be how to measure the spike rifle against the fleshborer, but there are few simple apples-to-apples tests to run for a 6" difference in range.

[papa smurf]

Well, tactical uses and concerns aside, I think that the reason most people don't use them is simply because they do not come in the boxed set/there are no bits to represent them.

I'm sure many out there would be willing to convert some, but it is so much easier to just use what you've got, so to speak. All the other options like fleshborers, spinefists, and devourers are there on the sprue.

Going along with this train of thought, I've never gone up against someone who uses Stranglewebs either. Although only being strength 2 and the fact that you can only take a limited number makes this not nearly as surprising as the lack of Spike Rifles seen in Tyranid armies.

So I'm sure there are some people who advocate their use on the tabletop, but for most people I would assume that it's easier for them just to use a weapon option that's already in the box. This is just an assumption, but it may explain why you don't see spike rifles that much.