Ok i've searched, i got nothing.
How much feet per/sec and energy is a 75gr projectile going to lose when compared with a 16" barrel?
Thanks.
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Ok i've searched, i got nothing.
How much feet per/sec and energy is a 75gr projectile going to lose when compared with a 16" barrel?
Thanks.
Look what I found using the ORANGE SEARCH button on the top of the page.
https://www.m4carbine.net/archive/in...p/t-26436.html
Thanks
note: use the search up at the top, not the other..
My 12" LMT piston using same ammo as direct gas Bushmaster 16" :
16"- 75 gr HPBT PRVI reloads w/ 21.5 TAC, AVG Velocity 2363fps
12"- 75 gr HPBT PRVI reloads w/ 21.5 TAC, AVG Velocity 2222fps
difference 141 fps, or 35.25 fps per inch between 16" and 12".
These were very light loads just trying to figure out the same thing as you were looking at. From my reading other peoples results it can run around 50fps per inch on hotter loads.
Not trying to discredit your help Iraqgunz, but that still doesn't answer his question. If anything, it just gave him more questions.
I have been searching for a while now on some hard data about how much velocity I'll be getting out of a 10.5" with Hornady 75gr. TAP in the .223 and 5.56 loadings. I can't come up with anything concrete...kinda frustrating...and trust me if I had the funds, I would do all the T&E myself (and post it for everyone else's benefit of course)
Thanks KBN.
The only reason i asked is i am trying to decide whether or not to go 556/223 or 6.8 for a 12.5 build.
I really wanted to stay 5.56/.223 and i *think* i will. I beileve a 62-75gr bullet will get the job done out to 300yds (which is the farthest i'd push it with a 12.5..if that far)
(note this is a hunting/range/maybe patrol if i ever find a job-make it through the academy, gun)
again Thanks guys.
I was under the impression that a 12.5 Noveske Crusader will chrono almost as much as a 14.5 colt barrel.
I did a search to find numbers, but only found people saying it was the same...
I would be tempted to get a 12.5 and a suppressor mount that reflexes over the barrel like an AAC MITER.
It's not for 12.5", or 75 grain loads, but you can see the trend. I talked to a gent at Federal/ATK recently, and he said the LE223T1 load in the table below was effective from a 10.5" for at least 125yd and up to 200yd, as far as initial upset and expansion goes. After that, it would basically behave like XM193. For my application (suburban LE), 125yds is plenty. For hunting however, depending on you're anticipated ranges and prey, these velocities/ranges may not be enough. My personal thought is that if you want an SBR, get 11.5" or less. Otherwise, a 14.5" with a perm'ed hider is only 2-3" longer overall than the 12.5", and you're saving the $200 tax stamp. Just my thoughts.
Attachment 7402
Chrono'ed on a F1 Shooting Chrony at 10' from the muzzle, by me. Speeds are in FPS.
Obviously, I'm not as high speed as Molon :). But as you can see, you're losing upwards of 350fps with the 4" reduction in barrel length.
BTW, the chrono I used is around $100. Works well enough for me.
Thanks for the info Wilco!
Great stuff wilco!
I think the 12.5 is a good "in between" length (between super short 10" and 16"). You dont lose too much velocity, or lose any maneuverability.
I'll probably go 12.5 just in case i want to add a suppressor later, cut down on OAL.
You're welcome, and I hear you on the 12.5" - certainly if you want it to be more effective at longer ranges, the added length helps.
Also, I don't know if it will become available to the public, but the new FBI contract round from Federal is a 5.56 NATO loading, and should get M855 type velocities. In theory, that would extend the "effective" range a bit over the duty load we use (223 pressure 55 grain). According to the guy I spoke to, they're also developing a SBR specific cartridge, which ATK says might be released later this year.
I'm a big fan of the balance the 12.5 brings for hunting applications and the OAL as well.
I'm reading where the 6.8 is really getting some impressive velocities out of SBR's...i think if I had to do it over again, this would have been my choice over 5.56.
If you really need the terminal performance at 300 meters, then go with 6.8.
If you go with 5.56, then I would choose the non fragmenting bullets such as the TSX or bonded SPs at that distance.
Ok i THOUGHT i had done my research here and understood the NFA process....then i went to my local class 3 dealer and my head is spinnning.
What i thought:
1. decide you want a sbr
2. get your lower engraved
3. fillout Form 1 completely (finger print, signature, ect)
4. Mail in form with $200 check for tax stamp
5. Wait for approval, once it passes...
6. Buy upper, have it shipped to house (just like a normal upper), bam you have your sbr.
What my dealer says...
1. Order upper (sent to the gunshop)
2. fillout Form 1 completely (finger print, signature, ect)
4. Mail in form with $200 check for tax stamp
5. Wait for approval, once it passes...
6. get your lower engraved...now you have a sbr.
Both of those timelines will work.
If you want to build your own SBR, there is no reason to involve the gunshop in the process. What your dealer says doesnt even make sense. One, uppers are not the NFA item. Second, if you buy an SBR from a dealer, it is on a Form 4 (transferring an existing NFA item). Since you are not making it, there is no need to engrave anything.
Thats what i thought...thanks.
A 300 meter shot with a patrol rifle is almost a non issue. While is CAN happen the likelihood is almost nil. For hunting, a 12.5 will perform well, especially with copper solids.
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