[EzGoingKev]

I am having a discussion about the benefits/drawbacks of 6.8 SPC vs 5.56 and one thing that has come up is size and weight.

The physical size is not a concern to me, but I would like to know the difference in weights.

Does anyone know the overall weights of the average 6.8 round and the weight of an average 5.56 round? I would like it in grams if possible.

I want to calculate what the weight difference would be of a 200 round SAW mag in 6.8 vs 5.56.

Thanks.

 

[paulosantos]

SSA 115 Gr. SMK is approximately 260 GR.
M193 is approximately 185 GR.

 

[stanc]

I can give weight in grains, but not grams.

Remington 6.8 w/115gr bullet = 268 grains
5.56 M855 Ball = 190 grains

5.56 M856 Tracer = 191 grains (In case the 1 gr difference matters to you. )

If you haven't considered it, the size difference may be more important than weight. For magazines of the same size, 5.56 has 30-rd capacity, 6.8 is 25-rd. For the SAW, a 200-rd container for 6.8 would be so large that I doubt the military would use it. A more likely capacity for a 6.8 SAW is 100 rounds.

 

[marinesg1012]

probably fit 75 rounds into a nut sack, and 150 or so rounds into a 200 round drum......

 

[Equalizer_2]

Remember 7000 grains to the pound and then you also have the aluminum 5.56 mags vs the steel mags for the 6.8

 

[owenslee]

A 62g 5.56 M855 round weighs 11 grams or .4 oz

A SSA 110g Pro Hunter 6.8 SPC weighs 16 grams or .6 oz on the same scale.

HTH

Kerry

 

[EzGoingKev]

Remember 7000 grains to the pound and then you also have the aluminum 5.56 mags vs the steel mags for the 6.8

So -
7000 grains = 1 pound.
1 pound = 16oz.
1oz = 28 grams.

So (7000/16)/28 = 15.265.
1 gram = 15.265 grains

A 190 grain 5.56 round would be 12.16 grams.
A 268 grain 6.8 round would be 17.152 grams.

Does this seem right?

 

[zoomie]

Sounds right. BTW, Google has a cool feature that you may not know about. It can convert for you right in the search bar. For example, type in "190 grains in grams" and click search. Above all the search results, it'll have an equation with the answer.

190 grains = 12.3117929 grams
268 grains = 17.3661079 grams

You can type any conversion with the format "XX units in units" and it'll convert.

"145 acres in hectares" gives you "145 acres = 58.6794181 hectares"
"29.92 in Hg in mb" gives you "29.92 inches of mercury = 1 013.0912 millibars"

Pretty freakin cool IMHO.

 

[coldair]

but when you factor in the killing power of the 6.8 it equals 5 of the 5.56 suddenly the 6.8 becomes the lighter more lethal round

 

[Equalizer_2]

The procedure looks right but I believe Owenslee is using a scale that will deliver the weights in both grains and grams at the push of a button.

If this is the case then the 110 gr 6.8 is half again as heavy as the 62 gr 5.56 but then the 75-77 gr 5.56 would be a bit heavier.

I am not sure of the conversion rate of ounces to grams.

 

[Equalizer_2]

Sounds right. BTW, Google has a cool feature that you may not know about. It can convert for you right in the search bar. For example, type in "190 grains in grams" and click search. Above all the search results, it'll have an equation with the answer.

190 grains = 12.3117929 grams
268 grains = 17.3661079 grams

You can type any conversion with the format "XX units in units" and it'll convert.

"145 acres in hectares" gives you "145 acres = 58.6794181 hectares"
"29.92 in Hg in mb" gives you "29.92 inches of mercury = 1 013.0912 millibars"

Pretty freakin cool IMHO.

That is cool, I have always done a search to find a convertor.

 

[EzGoingKev]

A 62g 5.56 M855 round weighs 11 grams or .4 oz

A SSA 110g Pro Hunter 6.8 SPC weighs 16 grams or .6 oz on the same scale.

HTH

Kerry

Thanks. It looks like we were writing at the same time.

Using your weight figures I come up with -
200 rounds 5.56 = 4.9 lbs
200 rounds 6.8 = 7.1 lbs

So roughly there is about a 2 lbs difference.

If you haven't considered it, the size difference may be more important than weight. For magazines of the same size, 5.56 has 30-rd capacity, 6.8 is 25-rd. For the SAW, a 200-rd container for 6.8 would be so large that I doubt the military would use it. A more likely capacity for a 6.8 SAW is 100 rounds.

probably fit 75 rounds into a nut sack, and 150 or so rounds into a 200 round drum......

I feel that the 150 or so round count would probably be more accurate. I do not agree with the assessment that a 200 round container of 6.8 ammo would be too big to consider. We used to carry 200 rounds of 7.62 for the M-60 so you are talking about a lot more weight and size.

Based on a size and weight increase, would you prefer the effectiveness and increased range of the 6.8 or stay with the 5.56 in the SAW platform?

While it is certainly important that everyone carries 5.56 and the SAW will accept AR mags, please do not factor them in for this discussion.

Thank you.

 

[marinesg1012]

I think if they are going to switch then we need to switch completly, I would rather have my SAW use the 6.8 then the 556... and I know you could carry 200 rounds of 6.8 on the rifle, but we use para saws and we use them like a M4, the 200 round drum is okay if your shooting it but just for carrying it around the 100 is better. then after blasting through that first 100, which goes quick, you slap the 200 round in there....

 

[EzGoingKev]

I think if they are going to switch then we need to switch completly, I would rather have my SAW use the 6.8 then the 556...

That is my thought exactly but there seems to be little movement on this.

Right now the Marine Corps is looking to replace the SAW. One of the complaints I have read about is that the SAW is too big/heavy for CQB, even with the para versions.

All I have seen submitted so far is modified full auto AR's and to me that is unsat. It is a joke to give the squad's A-gunner a 30 round magazine fed weapon.

I think whatever they replace it with should be belt fed and they should go up to the 6.8 to increase effectiveness. I think once you get on thing chambered in 6.8 the move completely switch would not be far behind. With the shorter barrels that are being issued now there needs to be a change to keep the weapon effective.

 

[marinesg1012]

I think the biggest reason they dont like the saw is that it is an open bolt weapon, it isnt cool if you are the first dude in a room and your get a click instead ofa bang, a MG is more prone to that kind of thing as compared to the M4....

the para saw while heavier then an m4 take up about the same amount of room...

 

[EzGoingKev]

I think the biggest reason they dont like the saw is that it is an open bolt weapon, it isnt cool if you are the first dude in a room and your get a click instead ofa bang, a MG is more prone to that kind of thing as compared to the M4....

You are absolutely correct, that is a big concern that I forgot about. Sorry.

The weapons that were submitted for replacement consideration shoot from a closed bolt in semi-auto and then switch to an open bolt for full auto. You would chamber the round in semi mode and then switch the selector switch to full auto I guess and then you would get that first round reliability of the closed bolt.

I cannot see why a re-tooled SAW couldn't be set to fire the first round closed bolt and the switch over also.

 

[stanc]

probably fit 75 rounds into a nut sack, and 150 or so rounds into a 200 round drum......

I feel that the 150 or so round count would probably be more accurate.

I agree with marinesg1012's estimate of how many linked 6.8 cartridges would fit into current 5.56 containers. When I opined that 100 rds would be a more likely capacity for a 6.8 SAW I was thinking of the long-standing practice of linking machine gun ammo into belts of 100 rds (7.62) or 200 rds (5.56). For a 6.8 SAW, it's possible that the military would opt to use 5.56 containers and just tolerate the reduced capacity, but that'd be contrary to what they've done for many decades.

I do not agree with the assessment that a 200 round container of 6.8 ammo would be too big to consider. We used to carry 200 rounds of 7.62 for the M-60 so you are talking about a lot more weight and size.

Back when I wore Army green, the container that attached to the M60 only held 100 rds. What on-gun container did you use that held 200 rds of 7.62 ammo???

 

[EzGoingKev]

Back when I wore Army green, the container that attached to the M60 only held 100 rds. What on-gun container did you use that held 200 rds of 7.62 ammo???

I am thinking of the ones that were used on mounted weapons.

Does anyone know the weight of a 7.62 round?

 

[stanc]

I am thinking of the ones that were used on mounted weapons.

Is that relevant to a 6.8 SAW?

Does anyone know the weight of a 7.62 round?

M80 Ball = 392 grains

 

[EzGoingKev]

Is that relevant to a 6.8 SAW?

Not really, my mind got stuck on the 200 round figure.