sbr experts wanted....help a noobie [Archive] - Glock Talk

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nickod
08-29-2011, 01:27
i have fallen in love with the idea of a 10.5" sbr but i want something that can reliably perform well out 100 yards and maybe even 150. i dont think a 10.5" 5.56 can do much better than 50yrds with fragmentation thresholds of even 5.56 tap. so what caliber? 6.8, .308, 6.5, or the new 300 blk ? i dont really know what im doing i just need pointed in the right direction. am i chasing a pipe dream thinking i can build a 10.5" that can still have effective ballistics out at 100 & 150 yards? also if any one knows how mk318 sost ammo will perform out of a 10.5", that info would be greatly appreciated! thanks again guys.

B.Reid
08-29-2011, 07:50
:wow:

WoodenPlank
08-29-2011, 09:52
With good ammo, a 10.5" can be effective well past 50 yards. Not as effective as an M4, Mk. 12 or M16, but still effective. I would suggest getting either 75gr TAP 5.56 (not the .223 version) or 77gr Black Hills. Unfortunately, I don't know offhand of anyone loading the 70gr TSX to match the 5.56 Optimized that's being used in Mk. 18s downrange.

As for accuracy, I can make very consistent hits on an 18" round plate at 150 yards with my 10.5" SBR shooting offhand without a sling. That's while using standard Federal XM193.

I also have met several professional trigger pullers that have hit military poppers at 550 and 750 yards with 10.5" and 12.5" barrels and ACOGs.

BBJones
08-29-2011, 11:04
i have fallen in love with the idea of a 10.5" sbr but i want something that can reliably perform well out 100 yards and maybe even 150. i dont think a 10.5" 5.56 can do much better than 50yrds with fragmentation thresholds of even 5.56 tap. so what caliber? 6.8, .308, 6.5, or the new 300 blk ? i dont really know what im doing i just need pointed in the right direction. am i chasing a pipe dream thinking i can build a 10.5" that can still have effective ballistics out at 100 & 150 yards? also if any one knows how mk318 sost ammo will perform out of a 10.5", that info would be greatly appreciated! thanks again guys.


Accuracy out of a 10.5 will be fine, but 5.56 does lose alot of velocity with that short of a barrel. If it was me and I wanted a 5.56 SBR, I would get a 12.5"

For 10.5" do not get a .308 that is insane. I would look into 300 AAC Blk. It can use all of the same parts as a 5.56 gun (except barrel). Round acts alot like 7.62x39 or 30-30 but can be made very accurate. It can be loaded sub-sonic too and works great with suppressors. That said if you don't reload, might not be a great idea.

What do you want the rifle for? Just to add to the collection or is there a specific purpose?

cyrsequipment
08-29-2011, 11:12
For 10.5" do not get a .308 that is insane.

Aw, come on... a .308 out of a 10.5" barrel would be sweet... The concussion alone would be lethal out to 50yds at least...:shocked:

A few years ago there was a little trend in my area for agencies to go with short barreled AR-10 type weapons... I saw 1 (one) team that actually trained with the weapon and touched it off in a building... that pretty much ended ALL interest in the system....

Glockdude1
08-29-2011, 11:18
Aw, come on... a .308 out of a 10.5" barrel would be sweet... The concussion alone would be lethal out to 50yds at least...:shocked:

A few years ago there was a little trend in my area for agencies to go with short barreled AR-10 type weapons... I saw 1 (one) team that actually trained with the weapon and touched it off in a building... that pretty much ended ALL interest in the system....

http://www.biggerhammer.net/mgshoot/kcrfall2001/saturday_hk51_flash__dalbert.jpg

http://t3.gstatic.com/images?q=tbn:ANd9GcT2bHuE6qtrqICRMbpz6faNEzSlsN2dUkzd8iRrIQkGQb40cYe0

:supergrin:

cyrsequipment
08-29-2011, 11:30
http://t3.gstatic.com/images?q=tbn:ANd9GcT2bHuE6qtrqICRMbpz6faNEzSlsN2dUkzd8iRrIQkGQb40cYe0

:supergrin:

:shocked:

Mommy....

Although, I DO want one, or two...

Glockdude1
08-29-2011, 12:17
:shocked:

Mommy....

Although, I DO want one, or two...

Christmas is coming up....... :supergrin:

Javelin
08-29-2011, 12:44
I would go 300 blackout and 8 inch barrel. Noveske makes a nice rifle.

nickod
08-29-2011, 13:32
yup.....i was thinking 300 blk too. im cunfused on how the sub-sonic ammo works though, at sub-sonic levels wouldn't it just poke a .30 hole creating a wound typical of a handgun? anybody know how this works? i have been all over the 300 blackout forum over at silencertalk.com but cant find any info on ammo and fragmentation or max effective ranges or any of that.

WoodenPlank
08-29-2011, 13:43
yup.....i was thinking 300 blk too. im cunfused on how the sub-sonic ammo works though, at sub-sonic levels wouldn't it just poke a .30 hole creating a wound typical of a handgun? anybody know how this works? i have been all over the 300 blackout forum over at silencertalk.com but cant find any info on ammo and fragmentation or max effective ranges or any of that.

The subsonic uses a 220 grain SMK bullet. I don't know about fragmentation velocities on either the 123gr or 220, but expect it doesn't need much - at least not with the 220gr SMK. Ammo is still somewhat scarce on the ground, so expect to either order online or reload your own.
I eventually want to go to 300BLK, but my 5.56 SBR has left me exceptionally happy in every way except muzzle blast/volume.

Javelin
08-29-2011, 14:44
yup.....i was thinking 300 blk too. im cunfused on how the sub-sonic ammo works though, at sub-sonic levels wouldn't it just poke a .30 hole creating a wound typical of a handgun? anybody know how this works? i have been all over the 300 blackout forum over at silencertalk.com but cant find any info on ammo and fragmentation or max effective ranges or any of that.

With subsonic 220gr ammo you are accurate out to about 300 yards. As far as ballistics and terminal penetration it is definitely lacking a tad in that department. Though if you want to use a little lighter bullet (120-150gr) the bullet really shines and has all the power you need for even larger game such as deer & even elk.

It is a very versatile round and as mentioned above it will become more of abundance later this year. I love my 10.5" Noveske 300 AAC Blackout and it has quickly become my favorite firearm.

http://glocktalk.com/forums/picture.php?albumid=288&pictureid=4651

nickod
08-29-2011, 16:50
yup.....the above pic is exactly why i have in mind. i cant wait till more info and research is available for the current ammo. and i especially cant wait till some improved ammo becomes more available. i really want to know what the 220 smk's are going to be doing in soft targets and barriers and at what ranges they will do it at.

Javelin
08-29-2011, 17:07
yup.....the above pic is exactly why i have in mind. i cant wait till more info and research is available for the current ammo. and i especially cant wait till some improved ammo becomes more available. i really want to know what the 220 smk's are going to be doing in soft targets and barriers and at what ranges they will do it at.

What terminal ballistics on soft targets are you wanting info on? It will do much better than a 5.56 for material penetration. Though the 75gr. 5.56 beats out almost everything in terms of soft tissue damage.

eracer
08-29-2011, 17:19
I would go 300 blackout and 8 inch barrel. Noveske makes a nice rifle.That's exactly what I thought....

Waiting on suppressor stamp.

http://i159.photobucket.com/albums/t135/eracer1111/2ndA/Noveske%20300%20BLK%20SBR/Noveske300BLK007_small.jpg

http://i159.photobucket.com/albums/t135/eracer1111/2ndA/Noveske%20300%20BLK%20SBR/Noveske300BLK010_small.jpg

Javelin
08-29-2011, 17:33
That's exactly what I thought....

Waiting on suppressor stamp.

http://i159.photobucket.com/albums/t135/eracer1111/2ndA/Noveske%20300%20BLK%20SBR/Noveske300BLK007_small.jpg

http://i159.photobucket.com/albums/t135/eracer1111/2ndA/Noveske%20300%20BLK%20SBR/Noveske300BLK010_small.jpg

That is sexy! Are you going with a 762SD can?

eracer
08-30-2011, 05:31
That is sexy! Are you going with a 762SD can?762-SDN-6

It mocks me from the dealer's holding area every time I visit...:supergrin:

BEER
08-30-2011, 10:40
if you're going to be shooting at 100-150 yards "regularly" why would you want an sbr instead of a full length rifle? it's my understanding that an sbr is intended to be compact for ease of movement in and out of vehicles and for close quarters work inside buildings.

don't get me wrong, if you just want an sbr to have one then more power to ya, but to me it sounds like you're after the wrong tool for the job and trying to pound a square peg into a round hole.

nickod
08-30-2011, 20:04
I agree with you. But explain to me why I see so many pictures of sbr's with magnified optics mounted such as the 300 blk pictured above. There has got to be a caliber ammo combo that will give an sbr an effective range of greater than 100 yards, no?

WoodenPlank
08-30-2011, 20:24
I agree with you. But explain to me why I see so many pictures of sbr's with magnified optics mounted such as the 300 blk pictured above. There has got to be a caliber ammo combo that will give an sbr an effective range of greater than 100 yards, no?

A lot of those magnified optics are along the lines of 1.1-4 or 1.5-5, enabling their use up close and at slightly longer ranges. A 5.56 SBR still is capable of making hits at several hundred yards, and many modern OTM bullets will fragment at lower (sub 1500FPS) velocities, so they are still effective. Like I said earlier, not as effective as a longer barrel, but I sure as crap wouldnt wanna get hit by a 75gr TAP out of an SBR at ANY distance.

nickod
08-30-2011, 22:11
What otm's frag down to 1500 fps? I thought heavy otm's frag less and less on their way down to 2200 or 2100 fps and then not at all. I'm talkin about 75 g tap and 77g smk. I have mo idea what speed 62g mk318 fails to perform at. If there is a round that leaves a 14.5" barrel at 3000 to 2600 fps and performs all the way down to 1500 fps.... I would love to hear about it.

WoodenPlank
08-30-2011, 22:38
What otm's drag down to 1500 fps? I thought heavy otm's frag less and less on their way down to 2200 or 2100 fps and then not at all. I'm talkin about 75 g

Short answer: Based on info I have gotten from friends deployed overseas using the Mk 12 and Mk 262 77gr OTM, they have seen consistent fragmentation and nasty wounds at 800m with the 77gr load. If I remember the info I got from Black Hills correctly, at that distance the Mk 262 is somewhere in the range of 1500FPS. If someone here is able to run the ballistics, they could confirm my memory or show that it's even worse than I thought it was. :whistling:

The Hornady T2 75gr has a reputation for slightly more devastating wounding capabilities than the 77gr, so I would have no worries about its terminal performance at 200-300 yards.

Some of the guys here (Surf, Murphy) have a lot more hands-on time with this in a combat environment, so if one of them is able to either confirm my thoughts or correct me, I'd appreciate it.

ETA: In general, longer bullets will fragment (all else being equal, such as bullet construction) at lower velocities due to their length.
Ideally, I would suggest using the 70gr Barnes TSX in a 5.56 loading, but I don't know offhand of a commercially available loading.

nickod
08-30-2011, 23:22
Thanks woodenplank. You alawys come with solid info. Just...I read the heavy otm thread over m4carbine.net many times and it stated around 2100 fps would be a generous fragmentation threthold for 75g tap. But I will take real life experience reports over scientific study any day

WoodenPlank
08-30-2011, 23:34
Thanks woodenplank. You alawys come with solid info. Just...I read the heavy otm thread over m4carbine.net many times and it stated around 2100 fps would be a generous fragmentation threthold for 75g tap. But I will take real life experience reports over scientific study any day

Here are the numbers I just ran. Velocity and barrel specs taken straight off a box of 75gr TAP 5.56 (#8126N). The rest of the info came off the Hornady LE site...

Calculator used (http://www.handloads.com/calc/)

2665 FPS muzzle velocity (14.5" barrel), .355 BC, 80deg temp, 100f altitude (Typical spring/fall day here in NW Florida) gives some of the following velocities...

50 yards: 2538
100y: 2420
150y: 2306
200y: 2195

According to that calc, the 75gr TAP wont drop below 2100 until approximately 250 yards. Now, if you WAG the velocity for the same load from a 10.5" (Quoting Arfcom, 20FPS loss per 1" of barrel removed - Edit to add that this drop has been higher in my experience, sometimes MUCH higher...upwards of 50-100 FPS per inch, depending on load) at 2585FPS...

50y: 2461
100y: 2345
150y: 2233
200y: 2123

You are still above that quoted 2100FPS threshold at 200 yards from a 10.5" barrel. I can't say for sure with the TAP, but I get the sneaking suspicion that itll still fragment below 2000 FPS.

Again, if someone can give me something solid to the contrary, I'd love to hear it, especially if it's got some real-world info to back it up, not just my wild postulating.

WoodenPlank
08-30-2011, 23:45
Some more interesting numbers, off the same calculator used earlier...

Mk. 262 using 77gr SMK (.362BC) from an 18" barrel is reported to be 2730FPS, roughly. At 800 yards, that puts velocity at barely over 1200 FPS. Seems like it still works rather nicely at that range, though...

nickod
08-31-2011, 00:16
I love this thread! Thanks woodenplank. I still think the numbers are a bit too generous. When I get to a computer I will link the heavy otm thread from m4carbine.net here so you can see what I'm referring to here as I'm I'm my phone right now

WoodenPlank
08-31-2011, 00:24
I love this these. Thanks woodenplank. I still think the numbers are a bit too generous. When I get to a computer I will link the heavy otm thread from m4carbine.net here so you can see what I'm referring to here as I'm I'm my phone right now

Even if my velocity numbers are high, you are still looking at a 75 grain projectile doing 2000 FPS or so out to 150+ yards. Even if it DOESNT fragment, that is quite a bit of energy being dumped into someone's body(666 foot pounds by my math), and a 10.5" barrel is plenty accurate enough to hit MoM at those distances if you do your part.

It's not the end-all-be-all of weapons. Nothing is. However, I would not and do not feel undergunned with a 10.5" SBR loaded with 75gr ammo. I'm not taking that gun into combat. It's a HD/SD and trunk gun, and (god forbid) would serve for SHTF duty. In any of those situations, if the threat is too far away to effectively engage with that SBR, then it's probably not one I really need to worry about.

nickod
08-31-2011, 00:56
Well put. I'm just the kind of girl who likes to know things. After all, knowing is half the battle - g.I. Joe

nickod
08-31-2011, 07:30
http://www.ar15.com/forums/t_3_16/283506_Hornady_5_56_TAP_versus_TAP_FPD__Heavy_OTM_Thread_.html


hope that worked. even if it didn't, copy and paste that in your search bar. the frag info is right there on the first page of the thread but, i would suggest reading the whole thing if this interests you. its a great thread. now if i could just get info like that on mk318 sost i would be set!!!