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Posted: 8/27/2019 2:13:26 PM EDT
Thinking about doing a pistol build in 5.56 and as it states using a 7 1/2" barrel.
Is there a specific grain ammo that will perform better in a short barrel configuration ? |
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I would look at the lightweight TSX options.
https://www.targetsportsusa.com/barnes-vor-tx-223-remington-ammo-55-grain-tsx-hollow-point-lead-free-bb223r2-p-109455.aspx Spendy, but they perform well at the velocities seen in short barrel 5.56. 77TMK is generally a good performer, but I'm not sure on frag distance from such a short barrel. |
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Sorry about that. 5.56 View Quote |
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Hornady 55gr sp will expand to ~.40 caliber and penetrate 13”-16” in gel at 1600fps impact velocity. Weight retention is ~60%.
1600fps impact gives an effective range from a 7.5” barrel (using a conservative 2400 fps muzzle velocity) of ~250 yards. I had a thread on it in which I shoot gel a while ago which is archived by now but if I find it I will link it. |
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My latest AR pistol was a 4.75" 300blk. With the KX3, it's downright pleasant to shoot.
I put a CMMG .22 adapter in my 7.5" AR. It's just too punishing w/ 556 and offers nothing in exchange for the punishment. |
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Kind of surprised nobody makes .223 or 5.56 optimized for an SBR. Or do they?
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Hornady makes 1 or 2 SBR rounds but they still are pretty slow out of a 10.5" barrel. A barrel as short as 7.5 makes it very difficult to maintain rifle velocities out of 5.56
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That's like asking "I'm buying a Corvette and swapping in a 2.0L 4-cyl engine. How do I make it go fast in a 1/4 mile?" Sorry, but at that barrel length you're severely compromising the performance of that caliber. If you want to go that short, at least move up to something bigger in diameter. View Quote View All Quotes View All Quotes Quoted:
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Sorry about that. 5.56 |
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Hornady 55gr sp will expand to ~.40 caliber and penetrate 13”-16” in gel at 1600fps impact velocity. Weight retention is ~60%. 1600fps impact gives an effective range from a 7.5” barrel (using a conservative 2400 fps muzzle velocity) of ~250 yards. I had a thread on it in which I shoot gel a while ago which is archived by now but if I find it I will link it. View Quote |
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Isn't the Blackhills 5.56 Barnes 50gr TSX supposed to be pretty good from a short barrel.
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I have the 7.5 in Marauder from PSA. I've put m855, xm193, 62, 55 grain wolf and Tula. Also some 77 grain something-or-other my buddy had. I couldn't hold much of a group off of a rest sighting it in at 25 yards. Maybe a 4-inch group. I was using a known good red-dot.
I had the first Barrel that came with it exchanged because of inaccuracy. The second Barrel was slightly better. I'm still minute of man at a hundred yards, maybe 8 inch group but as yet haven't been able to tighten the group's up. Can't speak to expansion at all. It is a very handy Blaster though and I do love it. I'm chaulking it up to user error at this point. I had a 10.5 and 16 in with me the day of and groups tightened up considerably as barrel length was added. I'm generally a pretty good shooter with a rifle. I guess it's the shorter Barrel that threw me off and magnified small movements I was making while squeezing. |
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https://www.AR15.Com/media/mediaFiles/3561/SBR-Low2-134332.jpgAs stated, too short for 5.56... My solution! View Quote |
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https://i.imgflip.com/390xjd.jpg https://www.AR15.Com/media/mediaFiles/138374/20190816_192647-1056864.jpg https://www.AR15.Com/media/mediaFiles/138374/20180729_181922-623222.jpg View Quote View All Quotes View All Quotes Quoted:
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https://www.AR15.Com/media/mediaFiles/3561/SBR-Low2-134332.jpgAs stated, too short for 5.56... My solution! https://www.AR15.Com/media/mediaFiles/138374/20190816_192647-1056864.jpg https://www.AR15.Com/media/mediaFiles/138374/20180729_181922-623222.jpg |
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The various lighter CCI gold dots are pretty good out of short barrels. I'd start with the 55gr.
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300 BLK... interesting thought. I have a Spike's Tactical/Multi lower, and since I have never attempted a build before, is that compatible for a 300 ? View Quote View All Quotes View All Quotes Quoted:
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I'd change caliber to 300 BLK at that length or .22LR I also think 7.5” is too short for 5.56. I would not go less than 10.3/10.5”. |
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I've got a 7.5" 5.56mm pistol. I already had 10.5" SBR and wanted something as compact as possible for travel.
I've killed two deer and at least a dozen coyotes with it up to about 100 yards. Federal 55 Grain TSX and Winchester 55 Grain Ballistic Silvertip, all DRT. |
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I've got a 7.5" 5.56mm pistol. I already had 10.5" SBR and wanted something as compact as possible for travel. I've killed two deer and at least a dozen coyotes with it up to about 100 yards. Federal 55 Grain TSX and Winchester 55 Grain Ballistic Silvertip, all DRT. View Quote |
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DO EET. https://i.ibb.co/XjYmvx9/IMG-3417.jpg https://i.ibb.co/Hp4y18w/69-D18232-425-F-4-F3-E-8148-B5-F02-ABF60-AF.jpg View Quote View All Quotes View All Quotes Quoted:
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I'd change caliber to 300 BLK at that length or .22LR https://i.ibb.co/XjYmvx9/IMG-3417.jpg https://i.ibb.co/Hp4y18w/69-D18232-425-F-4-F3-E-8148-B5-F02-ABF60-AF.jpg |
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That's impressive and dispels some notions I had about that bbl length for 556. View Quote View All Quotes View All Quotes Quoted:
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I've got a 7.5" 5.56mm pistol. I already had 10.5" SBR and wanted something as compact as possible for travel. I've killed two deer and at least a dozen coyotes with it up to about 100 yards. Federal 55 Grain TSX and Winchester 55 Grain Ballistic Silvertip, all DRT. But it's still coming out screaming: M193 with a 7.5" is still moving at 2,500 ft/s. https://rifleshooter.com/2015/12/223-remington-5-56mm-nato-barrel-length-and-velocity-26-inches-to-6-inches/ |
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Looks like I'll need to make space on the shelf for another caliber.....
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Looks like I'll need to make space on the shelf for another caliber..... View Quote If you aren’t going to mount a suppressor then an 11.5 to 12.5” 556 is pretty convenient and has enough Handguard to mount accessories and get a more forward grip on. |
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I've never had any mechanical issues with my 7.5. It feeds and shoots anything. Just don't get that delicious accuracy. I'm probably not the best shooter here though, I'm just a dude. Accuracy aside, that projectile is hauling ass when it leaves the barrel. A hell of a lot more effective than a pistol round.
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I've never had any mechanical issues with my 7.5. It feeds and shoots anything. Just don't get that delicious accuracy. I'm probably not the best shooter here though, I'm just a dude. Accuracy aside, that projectile is hauling ass when it leaves the barrel. A hell of a lot more effective than a pistol round. View Quote |
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I would look at the lightweight TSX options. https://www.targetsportsusa.com/barnes-vor-tx-223-remington-ammo-55-grain-tsx-hollow-point-lead-free-bb223r2-p-109455.aspx Spendy, but they perform well at the velocities seen in short barrel 5.56. 77TMK is generally a good performer, but I'm not sure on frag distance from such a short barrel. View Quote |
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Is it slower than from a longer barrel? Obviously. But it's still coming out screaming: M193 with a 7.5" is still moving at 2,500 ft/s. https://i2.wp.com/rifleshooter.com/wp-content/uploads/2015/11/m193-barrel-length-and-velocity-26-to-6-inches.png?w=667&ssl=1 https://rifleshooter.com/2015/12/223-remington-5-56mm-nato-barrel-length-and-velocity-26-inches-to-6-inches/ View Quote |
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Built a 7.5" a while back. It lasted one range trip.
I did not chronograph it because I was afraid of busting the thing. It certainly will let you know which ammo manufacturer uses a flash retardant. Swapped the barrel out immediately for a 10.5" and a linear comp. Sold the 7.5" to some other gullible soul. |
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My friend said the bullets will suck at 100 yards thru a 7.5" barrel. I asked if he would stand 100 yards away and I'll shoot at him so he can tell me how bad they suck. Never would.
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