WI Car 15 becomes standard rifle

What if the XM177s production hadn't ended in 1970 but instead there was an active push to have the Car-15 as the standard carbine for the army and all branches until the present day?

Just what kind of reception would it get in service?
What would its replacement be like?
Would the XM177 be exported?
How long would its service be?
 

Deleted member 1487

Seems more like a oversized pdw than a carbine though.
Pretty much the same dimensions as the 10-11 inch barrel Colt Commando/XM177. Except it had ammo tailored to the barrel the size of the weapon, rather than having the serious problem of using existing 5.56 NATO, which was designed for a 20 inch barrel and produced a huge fireball when fired out of anything less than a 14 inch barrel, requiring an only partly effective oversized flash suppressor. If you're going to go with an SMG sized carbine why not have ammo designed for that sort of platform rather than shoehorning in a round designed around a full sized rifle? There were some pretty huge advantages in using the smaller ammo of the Colt MARS, namely that much more ammo could be carried, plus no fireball or need for an oversized flash suppressor. Plus it was even more controllable in full auto or even single shot fire.
https://en.wikipedia.org/wiki/Colt_MARS
http://www.smallarmsreview.com/display.article.cfm?idarticles=1239

XM177:
COLT-XM-177E2-XM177-VIETNAM-REISSUE-AR-15-5-56-16inch-CRXM177E2_101069622_23034_40D5AEF7FD194ABB.jpg


Colt MARS:
607-GX-MARS_zps2d6c26eb.jpg

ColtMARSspecs.jpg


Plus it matches performance of the 5.56x45 out of a 10.5 inch barrel for a smaller, much lighter cartridge, while being able to use a lighter platform and with a normal flash suppressor.
https://www.thefirearmblog.com/blog...fense-weapon-calibers-005-the-5-56x30mm-mars/
 
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The Colt MARS seem to be an earlier FN P90 with a more conventional design. How does the 5,56x30 compare with the FN 5.7 round?
Someone had their pounds to Kg converter on reverse when they printed the MARS brochure.
 

Deleted member 1487

The Colt MARS seem to be an earlier FN P90 with a more conventional design. How does the 5,56x30 compare with the FN 5.7 round?
Someone had their pounds to Kg converter on reverse when they printed the MARS brochure.
Check the charts in the link, the 5.7x28mm is listed:
https://www.thefirearmblog.com/blog...fense-weapon-calibers-005-the-5-56x30mm-mars/
The FN round is significantly weaker. The MARS round performs basically the same as the 5.56 NATO round fired from a 10.5 inch barrel (i.e. the same as the CAR-15 and Colt MARS rifles) with lower recoil, lower round weight, and a lighter/smaller rifle. The 5.7x28 round is definitely lighter than the MARS round, but overall not significantly shorter or thinner.
 
Check the charts in the link, the 5.7x28mm is listed:
https://www.thefirearmblog.com/blog...fense-weapon-calibers-005-the-5-56x30mm-mars/
The FN round is significantly weaker. The MARS round performs basically the same as the 5.56 NATO round fired from a 10.5 inch barrel (i.e. the same as the CAR-15 and Colt MARS rifles) with lower recoil, lower round weight, and a lighter/smaller rifle. The 5.7x28 round is definitely lighter than the MARS round, but overall not significantly shorter or thinner.
I did. You're right. The MARS seems to be an excelent carbine. Another victim of the let's stick with the standard caliber I guess...
 
Pretty much the same dimensions as the 10-11 inch barrel Colt Commando/XM177. Except it had ammo tailored to the barrel the size of the weapon, rather than having the serious problem of using existing 5.56 NATO, which was designed for a 20 inch barrel and produced a huge fireball when fired out of anything less than a 14 inch barrel, requiring an only partly effective oversized flash suppressor. If you're going to go with an SMG sized carbine why not have ammo designed for that sort of platform rather than shoehorning in a round designed around a full sized rifle? There were some pretty huge advantages in using the smaller ammo of the Colt MARS, namely that much more ammo could be carried, plus no fireball or need for an oversized flash suppressor. Plus it was even more controllable in full auto or even single shot fire.
https://en.wikipedia.org/wiki/Colt_MARS
http://www.smallarmsreview.com/display.article.cfm?idarticles=1239

XM177:
View attachment 413542

Colt MARS:
View attachment 413544
View attachment 413545

Plus it matches performance of the 5.56x45 out of a 10.5 inch barrel for a smaller, much lighter cartridge, while being able to use a lighter platform and with a normal flash suppressor.
https://www.thefirearmblog.com/blog...fense-weapon-calibers-005-the-5-56x30mm-mars/


11.8 KGs empty?

I think some one has their pounds to KGs conversion back to front LOL
 

Deleted member 1487

I did. You're right. The MARS seems to be an excelent carbine. Another victim of the let's stick with the standard caliber I guess...
Same caliber as the 5.56 too. Just a different case diameter. Colt wanted a proprietary cartridge, which the US military was not about to invest in. So they shoehorned the 5.56 NATO into as small a package as possible, which is the modern M4. Honestly though, in the end it probably ended up saving them a fair bit versus converting to the MARS, but technically the MARS was the superior platform.

11.8 KGs empty?

I think some one has their pounds to KGs conversion back to front LOL
Metric is crazy, which is why us Americans stayed with the logical Imperial system.
 
Metric is crazy, which is why us Americans stayed with the logical Imperial system.
I’m not surprised given how heavy your weapons suddenly become when you use it! Better off sticking to good old Imperial for your 5.56mm x 30 (mm) calibrate Mars Carbine. Oh hang on....
 
A problem you would run into with the short barrel of the XM177 for general issue is significantly lower velocity. This will result in less fragmentation at distance with its lower lethality using the eras M193 ball ammo than Big Army would find acceptable. The 14.5" barrel on the M4 is what I would consider a bare minimum for general issue.
 

BigBlueBox

Banned
@wiking what is your opinion on the AAC Honey Badger carbine in .300 Blackout, or the SIG Sauer MCX in the same round? I think they could be good PDW weapons.
 

Deleted member 1487

@wiking what is your opinion on the AAC Honey Badger carbine in .300 Blackout? I think it could be a good PDW weapon.
In terms of using subsonic suppressed rounds within 150-200m it would be a fine PDW or spec ops weapon.
I think the Colt MARS with a M855A1 type bullet (lighter though to keep up velocity) would be a better carbine.
If we are talking about a standard rifle for the threats we are engaging today and for the foreseeable future (i.e. not a major nation state army with body armor) I'm partial to a 45cm barreled M16 platform with a FABRL type cartridge (38mm long chopped down 5.56 NATO case) with a CETME type 5.56mm round (i.e. very long aerodynamic aluminum cored round wrapped in a half jacket, which is very light and can be pushed at 1000mps with a low pressure load and would have very low recoil and good range).
 
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BigBlueBox

Banned
In terms of using subsonic suppressed rounds within 150-200m it would be a fine PDW or spec ops weapon.
I think the Colt MARS with a M855A1 type bullet (lighter though to keep up velocity) would be a better carbine.
If we are talking about a standard rifle for the threats we are engaging today and for the foreseeable future (i.e. not a major nation state army with body armor) I'm partial to a 45cm barreled M16 platform with a FABRL type cartridge (38mm long chopped down 5.56 NATO case) with a CETME type 5.56mm round (i.e. very long aerodynamic aluminum cored round wrapped in a half jacket, which is very light and can be pushed at 1000mps with a low pressure load and would have very low recoil and good range).
Body armor isn't just for nation-states anymore, it's becoming increasingly available and affordable for non-state actors. Latin American drug cartels are already issuing body armor to their enforcers. The most well-equipped Middle Eastern militants such as Hezbollah probably use body armor already. I think some big changes in small arms will occur in the next few decades as armies around the world try to develop a round that could that can reliably kill an enemy in hard body armor at 500 meters, but still has recoil low enough for usage in an assault rifle.
 

Deleted member 1487

Body armor isn't just for nation-states anymore, it's becoming increasingly available and affordable for non-state actors. Latin American drug cartels are already issuing body armor to their enforcers. The most well-equipped Middle Eastern militants such as Hezbollah probably use body armor already. I think some big changes in small arms will occur in the next few decades as armies around the world try to develop a round that could that can reliably kill an enemy in hard body armor at 500 meters, but still has recoil low enough for usage in an assault rifle.
What level of body armor are we talking about? Right now the M855A1 bullet out the M16 can pull that off. Otherwise a more powerful 5.56 cartridge with a heavier bullet could probably do it. If not then a more powerful M885A1-ified 6mm round could.
 

BigBlueBox

Banned
What level of body armor are we talking about? Right now the M855A1 bullet out the M16 can pull that off.
According to the NIJ, Level IV body armor with ceramic or steel inserts can stop both steel-core M855 and steel-core 7.62 NATO. In fact, it can also stop armor-piercing .30-06, although I suspect it can only do so once. Right now it's a bit difficult to acquire, but that's going to change as soon as the Chinese start mass-producing them.

Edit: Apparently it's sold online to civilians, but subject to export controls. I doubt those export controls are going to stop well-funded militants who are determined to acquire them.
 
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Deleted member 1487

According to the NIJ, Level IV body armor with ceramic or steel inserts can stop both steel-core M855 and steel-core 7.62 NATO. In fact, it can also stop armor-piercing .30-06, although I suspect it can only do so once. Right now it's a bit difficult to acquire, but that's going to change as soon as the Chinese start mass-producing them.
Got a link on the Chinese mass production?
I'd imagine the 6.5mm round with an exposed, hardened steel tip the army is working on with telescoping rounds will be their solution.
 
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