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Posted: 1/25/2019 1:26:07 PM EDT
[#1]
That's tiny. What's your muzzle velocity and ammo with a barrel that short?
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Posted: 1/25/2019 1:47:27 PM EDT
[#2]
Quote HistoryQuoted:
That's tiny. What's your muzzle velocity and ammo with a barrel that short? |
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Posted: 1/25/2019 1:50:45 PM EDT
[#3]
Quote HistoryQuoted: Enough. Ammo is Federal 55gr and Hornady 75hp. |
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Posted: 1/25/2019 1:51:02 PM EDT
[#4]
My teeth hurt all the way over here....
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Posted: 1/25/2019 2:05:06 PM EDT
[#5]
Quote HistoryQuoted:
My teeth hurt all the way over here....
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Posted: 1/25/2019 2:07:49 PM EDT
[#6]
Quote HistoryQuoted:
No kidding. I built a 7.5" upper before and sold it after the first range putting. I've never tried a flash can. |
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Posted: 1/25/2019 2:12:22 PM EDT
[#7]
Quote HistoryQuoted:
KX3 and similar make pretty good blast diverters. I've never tried a flash can. Quote HistoryQuoted:
Quoted:
No kidding. I built a 7.5" upper before and sold it after the first range putting. I've never tried a flash can. |
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Posted: 1/25/2019 2:16:05 PM EDT
[#8]
This guns purpose is intended for 30 yds and less. At those ranges it will perform flawlessly. It's not a 100yd hunting rifle.
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Posted: 1/29/2019 9:30:44 AM EDT
[#9]
When you go that short with 5.56, it is less effective than a 9mm pistol with the same sized barrel. If you ran a 300 blackout, then you would be okay, as I have a short barrel in my Sig Rattler. But 5.56 was never meant to run reliably or have effective stopping power as the powder used in most 5.56 ammo is slower burning and meant for longer barrels.
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Posted: 1/29/2019 5:47:07 PM EDT
[#10]
Quote HistoryQuoted:
When you go that short with 5.56, it is less effective than a 9mm pistol with the same sized barrel. If you ran a 300 blackout, then you would be okay, as I have a short barrel in my Sig Rattler. But 5.56 was never meant to run reliably or have effective stopping power as the powder used in most 5.56 ammo is slower burning and meant for longer barrels. (XM193 55gr vs 124gr Gold Dot)
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Posted: 1/29/2019 6:15:31 PM EDT
[#11]
Alright. What the hell?
Either OP posts pics and velocity info, or this thread is worthless. 
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Posted: 1/29/2019 6:21:29 PM EDT
[#12]
Quote HistoryQuoted:
Alright. What the hell? Either OP posts pics and velocity info, or this thread is worthless. i built 7.5" ars in 5.56 and x39, both have flash cans and both will rattle your fillings lose. on the plus side you can start a fire or toast marshmellows from the muzzle blast |
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Posted: 1/29/2019 7:05:08 PM EDT
[#13]
Quote HistoryQuoted:
^this i built 7.5" ars in 5.56 and x39, both have flash cans and both will rattle your fillings lose. on the plus side you can start a fire or toast marshmellows from the muzzle blast Maybe you just have lose teeth? 
Steve |
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Posted: 1/31/2019 1:48:01 AM EDT
[#14]
Quote HistoryQuoted:
When you go that short with 5.56, it is less effective than a 9mm pistol with the same sized barrel. If you ran a 300 blackout, then you would be okay, as I have a short barrel in my Sig Rattler. But 5.56 was never meant to run reliably or have effective stopping power as the powder used in most 5.56 ammo is slower burning and meant for longer barrels. 
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Posted: 1/31/2019 2:02:50 AM EDT
[#15]
Missed a perfect opportunity to build a short 300 imo
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Posted: 1/31/2019 11:23:12 AM EDT
[#16]
Quote HistoryQuoted:Even on a 6" barrel 5.56 blows away 9mm. Alternatively my 7" 300blk pushes a 110gr TAC-TX at 2,010fps and stays above expansion velocity (1,300fps) out to 275 yards. That's using the bullet as it was designed to be used. |
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Posted: 1/31/2019 11:31:17 AM EDT
[#17]
Quote HistoryQuoted:
Sure, for making small little holes at the range it's fine. For defensive purposes (OP called his rifle a personal defense weapon) you are using a bullet that might have more muzzle energy (55gr at, say, 2000fps = 489ftlb) than a 147gr (1080fps = 381ftlb) but no way to deliver that energy to the target because it is not being used as designed. You're about 1,000fps off the fragmentation velocity of a 55gr bullet but right in the sweet spot of what a 9mm or 45 is designed for. Alternatively my 7" 300blk pushes a 110gr TAC-TX at 2,010fps and stays above expansion velocity (1,300fps) out to 275 yards. That's using the bullet as it was designed to be used. Even at the reduced velocity, 5.56 will do that better than any 9mm you or I can buy. Of course I agree wholeheartedly that 110gr 300blk is a better choice than either when you want to go super short. |
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Posted: 1/31/2019 12:45:22 PM EDT
[#18]
Quote HistoryQuoted: "PDW's" were intended to be small, stowable and penetrate armor. Hence things like the P90 and MP7. Even at the reduced velocity, 5.56 will do that better than any 9mm you or I can buy. Of course I agree wholeheartedly that 110gr 300blk is a better choice than either when you want to go super short. PDW is a specialized role, and with specialized roles you give up X to get Y. The "little holes" some complain about are exactly what the 5.7x28 and 4.6x30 do. performance that you get out of 5.56 in a short barrel. 5.7 out of a P90 (10 inch barrel) gives around 1000 fps (56 gr). You can get up towards 2000 with a 40gr bullet, or even faster but thats around 28gr. 5.56 out of a SEVEN inch barrel gives around 2200 fps (55gr), closer to 2500 if you use 45gr. A ten inch AR in 5.56 absolutely blows the equivalent 5.7 in a P90 completely out of the water. Looking at numbers alone the 5.56 out of a 7 inch barrel very much beats out the other main PDW caliber in a longer barrel. Now this of course is raw numbers alone which are compelling, but I would like to see other factors such as flash/noise comparisons. I've also pointed out before a 7 inch AR is about the same size, and weight as an HK MP7, and 5.56 performs about the same or better than the 4.6x30. This of course is just stuff I skimmed off the Internet, would love a scientific comparison. But in any event, for the PDW role, a 7 inch (or maybe even shorter) fulfills the requirements. |
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Posted: 1/31/2019 1:48:25 PM EDT
[#19]
[fudd meme; I am comfortable with a 5" barreled 9mm pdw. If 30 147gr HST don't solve my personal problem, I don't think a micro 5.56 will either. ;fudd meme]
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Posted: 1/31/2019 2:15:34 PM EDT
[#20]
Quote HistoryQuoted:
When you go that short with 5.56, it is less effective than a 9mm pistol with the same sized barrel. If you ran a 300 blackout, then you would be okay, as I have a short barrel in my Sig Rattler. But 5.56 was never meant to run reliably or have effective stopping power as the powder used in most 5.56 ammo is slower burning and meant for longer barrels. I see tons of value in a package like this. I'm just glad I don't personally have to share a barricade with OP while he is throwing fireballs downrange. |
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Posted: 1/31/2019 2:38:42 PM EDT
[#21]
That short I’d go 9mm for cost effectiveness or 10mm for terminal performance.
However neither of those will be very effective at body armor. You need a light bullet going fast (relatively). In my opinion, that’s the trade off. |
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Posted: 1/31/2019 3:28:22 PM EDT
[#22]
Quote HistoryQuoted:
A 9mm PDW would {snip for speculation} wonder how the new wonder round(aka .350 Legend) will work at this barrel length |
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Posted: 1/31/2019 3:32:13 PM EDT
[#23]
Quote HistoryQuoted:
350 Legend If they use fast powders it may make a very good SBR load. |
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Posted: 1/31/2019 5:05:07 PM EDT
[#24]
Quote HistoryQuoted:
Odd, I have a 5.56 with 6.5" barrel and no issue with tooth rattle. I have a Black River Tactical Linier comp and that is all. Maybe you just have lose teeth?
Steve Quote HistoryQuoted:
Quoted:
^this i built 7.5" ars in 5.56 and x39, both have flash cans and both will rattle your fillings lose. on the plus side you can start a fire or toast marshmellows from the muzzle blast Maybe you just have lose teeth?
Steve |
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Posted: 1/31/2019 5:19:04 PM EDT
[#25]
Quote HistoryQuoted:
I've got a linear comp on my 5" barrel as well, and no tooth rattling going on either. Even at indoor ranges. I can't imagine a flashcan and a Linear comp having that much of a difference in concussion. Parallel walls aren't that bad. Shooting between barrels, through windows or anywhere else you can't get the muzzle past a barrier is downright painful compared to a longer gun
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Posted: 1/31/2019 9:10:15 PM EDT
[#26]
Had a 16" w/ a KAK flash can @ an indoor range. The young Marines shooting next to us asked if it was a .308. Sound just went downrange and bounced right back.
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Posted: 2/1/2019 12:28:02 PM EDT
[#27]
I've lurked this site for years....but I actually created an account today just to specifically ask....why?
Rough numbers for SBR's. Under 7 inches? 9mm (9mm +P) 7"-11"? .300blk +11" maybe 5.56 or some other caliber. For me, I won't go shorter than my 16" barrels in 5.56. After two trips to an indoor range, I dropped my 10.5" 5.56 for an 8.5" .300blk. I have two 10.5" 5.56 uppers just collecting dust...one has never been fired....and probably won't ever be (not by me anyway). It isn't just the noise, it is the wear and tear on the rifle. The BCG in the 5.56 would look and smell like I found in the rubble of a house that burned to the ground. A PDW? Where? I can't even imagine the noise, flash, and concussion 4.75" 5.56 would create inside of a house without earpro. From inside a car? LOL.... Energy-wise? Forget 9mm....a better comparison ballistics wise 22mag rifle. I have a bunch of 75gr Frontier BTHP and IMI 77GR OTM for my 16" and 20".....they will frag out to about 170 yards (2100 FPS) in the 16". With a 4.75" barrel, you are already below that threshold, and for heavy rounds they are probably key holing the moment they leave the muzzle. You are going to have to use some of the most expensive, 55 gr ammo on the market to expand at such low velocities. If not...you are just shooting .22 mag FMJ's...while flash banging yourself. |
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Posted: 2/1/2019 12:31:36 PM EDT
[#28]
( I see new accounts are limited in how long a post can be....part II)
As a comparison. I just scooped up a bunch of the Hornady Black 110gr V-Max in .300 on sale for $0.65 a round shipped. Out of an 8.5" barrel, that will expand out to roughly 200 yards while still hitting for over 600lb-ft-lbs. That is .357 Magnum (S&W 686) territory. I have the same micro slim KAK can on my 8.5" .300....with a 9" rail...so I actually have room for my hand....and a TLR1-HL. (The end of the KAK can sticks out about 1/2 of an inch beyond the rail...looks sick). Bottom line....for less than 4 inches of additional barrel, you could have much, much, much, much better weapon. You have the wrong caliber for a barrel that short.....sorry. Link to similar round...page 121 http://www.hornadyle.com/assets/site/files/Hornady-LE-Military-Application-Guide.pdf Another link on .308 V-Max at different FPS... https://thebulletterminal.weebly.com/110gn-hornady-v-max.html |
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Posted: 2/1/2019 12:49:44 PM EDT
[#29]
Quote HistoryQuoted:
I've lurked this site for years....but I actually created an account today just to specifically ask....why? Rough numbers for SBR's. Under 7 inches? 9mm (9mm +P) 7"-11"? .300blk +11" maybe 5.56 or some other caliber. For me, I won't go shorter than my 16" barrels in 5.56. After two trips to an indoor range, I dropped my 10.5" 5.56 for an 8.5" .300blk. I have two 10.5" 5.56 uppers just collecting dust...one has never been fired....and probably won't ever be (not by me anyway). It isn't just the noise, it is the wear and tear on the rifle. The BCG in the 5.56 would look and smell like I found in the rubble of a house that burned to the ground. A PDW? Where? I can't even imagine the noise, flash, and concussion 4.75" 5.56 would create inside of a house without earpro. From inside a car? LOL.... Energy-wise? Forget 9mm....a better comparison ballistics wise 22mag rifle. I have a bunch of 75gr Frontier BTHP and IMI 77GR OTM for my 16" and 20".....they will frag out to about You are going to have to use some of the most expensive, 55 gr ammo on the market to expand at such low velocities. If not...you are just shooting .22 mag FMJ's...while flash banging yourself. 170 yards on the 10.5" 5.56 using 77gr. |
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Posted: 2/1/2019 1:37:26 PM EDT
[#30]
Quote HistoryQuoted:
I've lurked this site for years....but I actually created an account today just to specifically ask....why? Rough numbers for SBR's. Under 7 inches? 9mm (9mm +P) 7"-11"? .300blk +11" maybe 5.56 or some other caliber. For me, I won't go shorter than my 16" barrels in 5.56. After two trips to an indoor range, I dropped my 10.5" 5.56 for an 8.5" .300blk. I have two 10.5" 5.56 uppers just collecting dust...one has never been fired....and probably won't ever be (not by me anyway). It isn't just the noise, it is the wear and tear on the rifle. The BCG in the 5.56 would look and smell like I found in the rubble of a house that burned to the ground. A PDW? Where? I can't even imagine the noise, flash, and concussion 4.75" 5.56 would create inside of a house without earpro. From inside a car? LOL.... Energy-wise? Forget 9mm....a better comparison ballistics wise 22mag rifle. I have a bunch of 75gr Frontier BTHP and IMI 77GR OTM for my 16" and 20".....they will frag out to about 170 yards (2100 FPS) in the 16". With a 4.75" barrel, you are already below that threshold, and for heavy rounds they are probably key holing the moment they leave the muzzle. You are going to have to use some of the most expensive, 55 gr ammo on the market to expand at such low velocities. If not...you are just shooting .22 mag FMJ's...while flash banging yourself. 55gr .223 (not even 5.56) out of a 5" barrel has a mv of 1861fps. 40gr .22 mag from a 5" barrel has a mv of 1433fps. In other words, a 5" 5.56 has 423ft-lbs at the muzzle, as opposed to a 5" .22 mag's 182ft-lbs. That is a 133% increase - over 2.3x as much energy, even if there is no expansion. And if you bump both of them down to 4" barrels, the .223 still has 104% more energy than the .22mag. http://www.ballisticsbytheinch.com/ No one said you had to use a 4.75" 5.56 gun. It isn't for everyone. OP obviously likes it. I'm glad you like the 300blk. I also like the 300blk. But you're just wrong if you think that with a 4.75" 5.56 "you are just shooting .22 mag FMJs". |
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Posted: 2/1/2019 1:40:20 PM EDT
[#31]
Quote HistoryQuoted:
That short I’d go 9mm for cost effectiveness or 10mm for terminal performance. However neither of those will be very effective at body armor. You need a light bullet going fast (relatively). In my opinion, that’s the trade off. something rated at 1600fps and 800ft lbs be like a 2x4 swung at you by the rock and anyway that's why the 308 pistol is there for backup |
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Posted: 2/1/2019 2:23:48 PM EDT
[#32]
Quote HistoryQuoted:
wut? 55gr .223 (not even 5.56) out of a 5" barrel has a mv of 1861fps. 40gr .22 mag from a 5" barrel has a mv of 1433fps. In other words, a 5" 5.56 has 423ft-lbs at the muzzle, as opposed to a 5" .22 mag's 182ft-lbs. That is a 133% increase - over 2.3x as much energy, even if there is no expansion. And if you bump both of them down to 4" barrels, the .223 still has 104% more energy than the .22mag. http://www.ballisticsbytheinch.com/ No one said you had to use a 4.75" 5.56 gun. It isn't for everyone. OP obviously likes it. I'm glad you like the 300blk. I also like the 300blk. But you're just wrong if you think that with a 4.75" 5.56 "you are just shooting .22 mag FMJs". I stated "a better comparison ballistics wise 22mag rifle." The rifle part is key. Said weapon isn't all that much more powerful than a 40gr, .22mag (rifle) round out of a 16"-15" barrel (Henry or 10/22 style weapon). We are talking about a small hole and and trying to find the right rounds to expand or frag. |
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Posted: 2/1/2019 2:52:25 PM EDT
[#33]
Quote HistoryQuoted:
You may have missed what I typed in the first part, and only caught the 2nd part. I stated "a better comparison ballistics wise 22mag rifle." The rifle part is key. Said weapon isn't all that much more powerful than a 40gr, .22mag (rifle) round out of a 16"-15" barrel (Henry or 10/22 style weapon). We are talking about a small hole and and trying to find the right rounds to expand or frag. Quote HistoryQuoted:
Quoted:
wut? 55gr .223 (not even 5.56) out of a 5" barrel has a mv of 1861fps. 40gr .22 mag from a 5" barrel has a mv of 1433fps. In other words, a 5" 5.56 has 423ft-lbs at the muzzle, as opposed to a 5" .22 mag's 182ft-lbs. That is a 133% increase - over 2.3x as much energy, even if there is no expansion. And if you bump both of them down to 4" barrels, the .223 still has 104% more energy than the .22mag. http://www.ballisticsbytheinch.com/ No one said you had to use a 4.75" 5.56 gun. It isn't for everyone. OP obviously likes it. I'm glad you like the 300blk. I also like the 300blk. But you're just wrong if you think that with a 4.75" 5.56 "you are just shooting .22 mag FMJs". I stated "a better comparison ballistics wise 22mag rifle." The rifle part is key. Said weapon isn't all that much more powerful than a 40gr, .22mag (rifle) round out of a 16"-15" barrel (Henry or 10/22 style weapon). We are talking about a small hole and and trying to find the right rounds to expand or frag. A 115gr 9mm from a 5" barrel is closer to .223 than that @ 1166fps/347ft-lbs - and almost exactly the same with a 16" barrel - 1295fps/428ft-lbs. Sorry man, you just aren't right. Also if OP wanted a 16" rifle then he wouldn't be running a 4.75" barrel. Apples to apples, please. ETA: the 55gr UMC .223 clocked 1955fps@ 6" and 1861fps@ 5", vs the xm193 55gr 5.56's 2202fps@ 6", so it's reasonable to conclude, despite not having data for the 5.56@5" that it is probably around 2000fps or so, which makes the difference even more. A 5" 5.56 shooting 55gr XM193 is going to be pushing 500ft-lbs, which is more than 50% more energy than a 16" .22mag I will also add that 62gr Federal Fusion, which is cheaper than 110gr Hornady Black 300blk and, should expand at pretty low velocities. Federal has said that based on their calculations, it should still expand down to 1350fps, but even if you bump that up to 1500 or 1600, it is well within PDW range for a 4.75" 5.56 or .223 and will provide better terminal ballistics than either a 9mm or a .22 mag. |
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Posted: 2/1/2019 3:50:51 PM EDT
[#34]
@Daggertt:
I'm not sure what you are looking at, but from the link you posted (which was the same link I used). Those top .22 mag rounds from 16 to 18 inches are in the 350 to 360 ft-lbs range....with many well over 2000 fps. Apples to apples? My first post stated that 9mm was better below 7 inches. More importantly, we are talking about a .22/.223 caliber bullet and hole (vs a 9mm/.355 hole) if said round does not have the velocity to expand/frag. Also, his barrel isn't 5 inches, it is 4.75 inches. In 9mm, that might not matter as much. In 5.56, that makes a big difference. So a 4.75" 5.56 round will be UNDER 2000 fps using you own numbers. While he might be close to 500lb-ft, (because of the heavier bullet over 40gr...assuming he is using 55gr), he is below the needed velocity to to frag for a lot of rounds. Outside of special ($$$) bullets, he is basically punching .22 caliber holes. That leads back to a .22 mag comparison being better than 9mm. How many 55gr 5.56 (not .223) rounds expand below 2000 fps? And that still leaves out just how crappy shooting a 4.75" 5.56 round would be. As a toy? Whatever....his money. I'm sure it looks pretty cool and throws a giant fireball. As an actual PDW? The barrel is too short to make good use of 5.56. A different caliber, or a longer barrel is a better choice if he is serious. |
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Posted: 2/1/2019 4:22:54 PM EDT
[#35]
Quote HistoryQuoted:
@Daggertt: Also, his barrel isn't 5 inches, it is 4.75 inches. In 9mm, that might not matter as much. In 5.56, that makes a big difference. So if a 5" barrel produces 2,000 FPS (and that sounds really generous if a .223 is at 1,860) knock 10% off that and you're at 1,800fps -- ME within about 10ftlb of a 9mm while giving up entirely the ability for the bullet to transmit that force to the target. |
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Posted: 2/1/2019 6:01:23 PM EDT
[#36]
Quote HistoryQuoted:
@Daggertt: And that still leaves out just how crappy shooting a 4.75" 5.56 round would be. As a toy? Whatever....his money. I'm sure it looks pretty cool and throws a giant fireball. As an actual PDW? The barrel is too short to make good use of 5.56. A different caliber, or a longer barrel is a better choice if he is serious.
Sure there a're better rounds out there, and worse rounds in true PDW's. This setup provides the benefits of a PDW without the need to run a different round from the rest of my rifles. It's not efficient, but it does the job. I'm not going to war with the thing, after all. Just want an alternative to travel with than just a handgun. Drops right into my laptop bag and can go anywhere with me and no one knows. |
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Posted: 2/1/2019 6:19:40 PM EDT
[#37]
Quote HistoryQuoted:
Keep in mind that, if we assume barrel length is measured to ATF specs (i.e. from the bolt face) the cartridge size needs to be subtracted. So 1.75" off a 5" barrel leaves 3.25" of travel (and hence acceleration) for the bullet. 1.75" off a 4.75" barrel leaves 3" of travel for the bullet -- a nearly 10% reduction. So if a 5" barrel produces 2,000 FPS (and that sounds really generous if a .223 is at 1,860) knock 10% off that and you're at 1,800fps -- ME within about 10ftlb of a 9mm while giving up entirely the ability for the bullet to transmit that force to the target. Quote HistoryQuoted:
Quoted:
@Daggertt: Also, his barrel isn't 5 inches, it is 4.75 inches. In 9mm, that might not matter as much. In 5.56, that makes a big difference. So if a 5" barrel produces 2,000 FPS (and that sounds really generous if a .223 is at 1,860) knock 10% off that and you're at 1,800fps -- ME within about 10ftlb of a 9mm while giving up entirely the ability for the bullet to transmit that force to the target. |
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Posted: 2/1/2019 7:40:50 PM EDT
[#38]
Quote HistoryQuoted:
Exactly. I was never saying 223 is the best caliber for a short barrel. I was contesting the assertion that the ballistics are closer to 22mag than 9mm. I think we've established that. If you are below an expansion or fragmentation threshold, you have no way to transfer that additional energy. You have to hope to bullet tumbles or else you have simply made a very small hole....223 to be exact. A bullet that makes a small hole and passes through is not optimal. That 9mm is a much larger bullet...it can transfer more energy and make a much larger hole. You can find .45ACP rounds that do 500 ft-lbs....but they make a much bigger hole. Most subsonic ammo does not expand (.300 subs are right in this energy level)....you make big holes (or head shots) and the target bleeds out. |
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Posted: 2/2/2019 7:42:09 PM EDT
[#39]
Quote HistoryQuoted:Most subsonic ammo does not expand |
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Posted: 2/2/2019 8:13:04 PM EDT
[#40]
Quote HistoryQuoted:
When you go that short with 5.56, it is less effective than a 9mm pistol with the same sized barrel. If you ran a 300 blackout, then you would be okay, as I have a short barrel in my Sig Rattler. But 5.56 was never meant to run reliably or have effective stopping power as the powder used in most 5.56 ammo is slower burning and meant for longer barrels. |
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Posted: 2/2/2019 8:32:29 PM EDT
[#41]
Quote HistoryQuoted: My 7.5'' 5.56 still has more velocity than a 16'' 9mm. At close range, I can shoot my 7.5'' through the width of a 4x6. Sure, a short barrel makes a 5.56 less effective but it is still packing some punch. |
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Posted: 2/2/2019 10:42:32 PM EDT
[#42]
Fusion rounds would still open at that velocity.
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Posted: 2/3/2019 12:50:44 PM EDT
[#43]
1, 2, 3, 4, or 5 shots through the kill zone is going to stop anything the weapon is intended for, this barrel length in under 50 yds will still do the same job in the same amount of time, with the same ending result. The argument that some argue is just foolish.
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Posted: 2/3/2019 1:37:00 PM EDT
[#44]
Quote HistoryQuoted:
Fusion rounds would still open at that velocity. Those are 62gr .223 rounds, not 55gr (lighter) 5.56 rounds (hotter)...so they will be slower. (Although I think the MSR's might be loaded a hair warmer for .223) According to the chart, a 55gr .223 round out of a 5" barrel is doing 1861 FPS. I'm not sure what the heavier round out of a shorter (4.75") barrel would do in terms of expansion range, it would would slow the round down. That would be taking one of the best rounds on the market, and turning the expansion range number possibly into single digits. That circles back to a couple of points from earlier. 1. This is clearly a super duper short range weapon. Where is it going to be used? If this is fired indoors without earpro....you may flashbang yourself. Clearly any non-suppressed weapon will be loud indoors, but 4.75" 5.56 will be obnoxious. 2. Even if you use the best rounds available (Fusion/Speer, Barnes) and happen to get expansion range in the "couple dozen yards" territory, it is still hard on the gun (and shooter) because 5.56 is at it's best in 20"'s of barrel, and efficiency falls off a cliff after 10.3". This set-up is about as inefficient as you can get for 5.56. You can make it work (poorly), but it is pounding a square peg in a round hole with a sledge hammer...when a round was already available. A different caliber (9mm, .45, .300) and/or a little more barrel is a much better choice for a true PDW. 
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Posted: 2/3/2019 4:05:11 PM EDT
[#45]
That 1st chart is tremendously helpful, thank you.
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Posted: 2/6/2019 8:19:53 AM EDT
[#46]
one load that I would think deserves investigation would be that 53gr v-max. Yes it's a varmint bullet, however with it's lighter construction it just may work perfectly at the working velocity of these PDW's or Micro pistols. same could be said about the 60gr v-max or nosler's varmageddons.
Just look at how the 300blk behaves with a 110gr "varmint" bullet. it acts like an controlled expansion bullet at its lower velocity. |
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Posted: 2/6/2019 8:28:05 AM EDT
[#47]
Quote HistoryQuoted:
one load that I would think deserves investigation would be that 53gr v-max. Yes it's a varmint bullet, however with it's lighter construction it just may work perfectly at the working velocity of these PDW's or Micro pistols. same could be said about the 60gr v-max or nosler's varmageddons. Just look at how the 300blk behaves with a 110gr "varmint" bullet. it acts like an controlled expansion bullet at its lower velocity. I'll also be curious what kind of velocities we can get from the 350 Legend in super short barrels. There's something to be said for swept volume. |
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Posted: 2/7/2019 10:30:56 AM EDT
[#48]
Quote HistoryQuoted:
one load that I would think deserves investigation would be that 53gr v-max. Yes it's a varmint bullet, however with it's lighter construction it just may work perfectly at the working velocity of these PDW's or Micro pistols. same could be said about the 60gr v-max or nosler's varmageddons. Just look at how the 300blk behaves with a 110gr "varmint" bullet. it acts like an controlled expansion bullet at its lower velocity. The 53gr V-Max is a .223....but it is "super performance"... .so it could have a little more zip like a 5.56. Hornady does makes a 60gr V-Max round in 5.56...in steel. Those might work. I don't know how far they would range out....and at the lower energy with a varmint round, I'm not sure if they are still defeating body armor....but they should work out of a micro AR on soft targets. Still.....my 8.5" fits in my backpack (has a Law folder). An additional couple of inches (3.75" in my case) and caliber makes a huge difference. Here is an easy energy calculator. http://www.larrywillis.com/bullet-energy.html 110gr V-Max at roughly 2075 fps = 1051.43 ft-lbs. 53gr V-Max at roughly 2000 fps = 470.64 fl-lbs. On a separate note....before I switched over to a .300, I had my 10.5" 5.56 for HD. I used Frontier 55gr HP in 5.56 as my HD round. I wanted something fast and light that would not over-penetrate. |
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Posted: 2/7/2019 5:20:52 PM EDT
[#49]
there is always a armchair builder tossing hate because they cant build something nice.
Sort of like SLR building their 7.5 308. someone had to up my 10.5. I have my 7.5 with a surefire warden still rattles your teeth but nothing like my 308 would love to see a pic of it. and 5" barrel anyone on the receiving end isn't going to critique the build 
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Posted: 2/7/2019 10:24:35 PM EDT
[#50]
Quote HistoryQuoted:
there is always a armchair builder tossing hate because they cant build something nice. 
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