Duty SBRs Bullets, barrels, and Compromise

Lets try this again an see if it collapses my phones browser as I try to hit publish.

Our armorer wants to replace our 13 year old 14.5" Colt M4A1's with 11.5" guns. I've researched the net and Docs stickies but haven't found this exact answer.  We use Fed LE 223T1 with the 55grn TBBC now.  As these are Swat guns our needs are for a bullet that performs out of the 11.5" barrel preferably out to between 100-200 yards.  I will define performs  as acceptable expansion at velocities produced from an 11.5" gun at  a minimum of 100 yards but ideally beyond that somewhat but not more than 200 yards is needed.  Performance through auto glass and similar intermediate barriers is required at say 75 yards or less.  

Anyone know what the minimum velocity is required for LE223T1 to perform so that I can determine the max effective range of our current ammo if we went to 11.5" guns?  What load gives us the best compromise of performance against intermediate barriers plus the "mostest" distance with the bullet still performing in a people medium?  FBI load, 77 grain OTM?

I'm not personally set on 11.5 or 14.5 but I dont want an MP5 sized gun that is only good out to 70 yards on people.  I also have to be able to articulate this argument.

Original Post

We use the T3 (62 gr variant of the same load).  In our 16" guns, we've had no issues.  In our 10.5" guns, we've had several instances of the rounds not expanding, and merely punching straight through.  Federal said the shorter barrels weren't giving enough velocity for the round to expand reliably.  Again, different grain weights, but that's been our experience FWIW.

Your best bet is a 5.56 mm (not .223) loading of a barrier blind projectile.  The 5.56 mm Federal 62 gr Trophy Bonded Bear Claw (TBBC) bonded JSP (XM556FBIT3) and 5.56 mm Winchester 64 gr solid base bonded JSP (Q3313/RA556B) developed for the FBI are optimal solutions, the Black Hills 5.56 mm 50 gr TSX loading and Hornady 5.56 mm 55 gr GMX are also acceptable options.  Speer Gold Dot 62/64 gr 5.56 mm loadings would also work well.

FMFBEST...

You raise valid and interesting concerns. We also run the colt system with 14.5" barrels. I'm curious which make / brand upper he want to purchase. How much are aftermarket uppers? I know when you add up total costs it's very hard to beat the LE department cost of a brand new rifle of $900.00 .... isn't it like putting new heads on an old block, the lower is still 13 years old. BTW, the new Colt lowers now come ambi, that is a huge advancement for southpaws and  all the others who shoot off hand. I know that when you start the conversation about need to replace rifles, those wearing the gold start getting bunched up, but what about the 13 year old optics that they are using? Here, we have a SWAT rifle replacement schedule... we replace 5 complete (cases, slings, optics, mags, lights...etc) at a time. 

I too am on the fence about the NEED to run 11.5 or 10.5 inch systems. And, having to shop for a new ammo replacement and maybe even issuing different loads for different rifles is a pain. Do you run cans on these SWAT rifles? That's another consideration on keeping the shorties running reliable with the right load. What do you do with the "retired" rifles? We convert them to semi only and press them into to service in patrol. I don't think we could do that with shorter rifles. 

So glad I caught your attention Doc.  So given that FBI load whats my max ballistically effective range with that round out if an 11.5 gun?  Thats my real question.  Can I effectively engage that guy across the big box parkinglot and have enough gun when the bullet gets there or is it just .22 holes in him?

fmfbest posted:

could you elaborate on the failures you have had. Were they in people or gel?  Ranges?  

They were in people, not gel.  They weren't failures so to speak, in that they still killed the bad guys, but they didn't expand like they have when we've shot people with longer barrels.  Ranges were probably in the 15 yard zone (ish), and no significant barriers other than clothing.  

Doc GKR is the gold standard here.

Also consider this.
The hit ratio in gunfights varies from agency, geo location, and circumstances.

The big issue is not necessarily the caliber, ballistic co-efficient, bullet weight, bullet configuration, and so on.
Sometimes we get hung up on the esoteric minutia of inconsequential increments.
What we really need to prioritize on is the final resting place of the bullet in your chamber,  and those in the magazine.

Everything is a compromise. You can't move in one direction without something happening in the other.

Re SBR. Ad Gary stated, nothing shorter in 556 than 11.5, and 12.5 is better.

Buford may chime in here, but I believe that the Bu went to 11.5 across the board.
And oh yeahn no more RRA shit

Bullet placement will always be king but we cant knowingly go to a combo that we knew would not allow the bullets ti perform as designed.  I guess tomorrow I  can chono my personal 11.5 BCM and get a number at 100 yds then call our Federal guy and ask what the bottom threshold is for the bullet to expand beyond .22 diameter.  I will be able to figure then the max effective range if the combo.  I just dont want a 60-70 yard gun.

Do you NEED to go from a 14.5" to a 11.5" gun for everyone? How about getting replacement 14.5" guns/uppers and maybe a few 11.5" guns/uppers for entry. 

 

 

 

Joined: 4-23-04                                          Location: SW Ohio

FMF, if memory serves a neighboring team is running the T223 55gr TBBC in their Colt Commandos (their road guys get the .223 62gr TBBC), PM and I'll try to get you an email. AFAIK they allow a mix of personally owned 11.5-16" tubes, but I'm not sure if a beat guy with a personally-owned 11.5" SBR gets 55gr or 62gr?

 

Condition Yellow: For a Longer, Happier Life

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