Hey guys,
I’ve been searching around here but have been unable to find the answer to my questions.
I’m thinking of SBR’ing my rifle in the next year or so, and wanted to go with a 10.5" upper. What type of effective range can be expected with this setup? And does the use of TAP or other ammo aid in offsetting performance loss from the shorter barrel?
Thanks for any feed back you guys can give me.
-RD62
I think if you search out some of KevinB’s posts you will get some good info on the max effective range of Mk18’s;)
There have been kills out to 300yds with shorties. As far as ammo selection goes that would largely depend on twist rate & quality of the ammo being used. If you’re looking at a LMT 10.5 I believe it’s 1/7. Can you be more specific about “performance loss?” You will loss some velocity, but unless you’re gonna be shooting long range comps IMO it’s negligible for what a SBR is designed for. I don’t know what you’re gonna be using the SBR for so it’s hard to say. Some SBR’s can be fickle as to how the function vs. the longer carbines or rifles. SBR’s in my world are used for CQC & for ease of deployment, i.e., from vehicle’s & compactness for carry, etc.
Typically 50-100yrds will give you great results from an SBR on the range depending on your planned usage. That’s not say you can’t reach farther & be effective. You may have to experiement with buffer weights, bolt carrier & extractor upgrades to get optimal function out of yours. My CMMG shoots great with a H2 buffer, semi auto carrier & BCM silcon spring, black bumper, Crane o-ring & new manufacture Federal .223 55gr ammo.
“Effective range” is a touchy subject. On the one hand you have people that crunch the numbers for the velocity of the round, research out the minimum velocity that is needed to achieve fragmentation, and spit out a “fact” like “the 10.5” barrel has a maximum effective range of 47.5 meters!" Then you have the guys that have carried one in combat situations and have actually shot people with them that come back with “I dunno about all that math, I shot a guy at 100 meters with my 10.5” barrel and he dropped like a rock. Headshots are a bitch".
Neither one is truly wrong, but which one do you listen to? And at the end of the day, does it really matter? In some ways it’s similar to the old handgun “which carry ammo is best” debates. It’s not about barrel length, or velocities, or ammo. It’s about shot placement.
However, being that I’m neither a number-cruncher nor a people-shooter, I’m probably way off base on all of this and will simply say that I view my 11.5" barrel gun as a 50 meters and in gun.
Hey guys. I appreciate the responses so far.
I understand that this may be one of those very subjective questions, and that shot placement is obviously going to be of utmost importance no matter what the barrel length.
And my question about effectiveness does stem from the lower velocities found with the shorter barrels, which under most conditions I think would reduce the tendancy to fragment or expand dependant upon the type of ammo used.
I’ve seen the 45meter number you mentioned Rob, which I think was using M193, right? That’s why I ask about other non fragmenting loadings, and wether they may effect accepted effective range in any way. I don’t know educate me please!
I have made hits on targets @100 yards with my pistol before, but consider it’s accepted effective range to be somewhat less than that based on ballistics and my ability to hit consistantly and accurately with it. I would consider the criteria for an SBR to be similar. Would you guys consider that to be reasonable?
I am not military, and am no longer LE, so none of my rifle/pistols are duty weapons. They are strictly for protection of me and my family, and for use at the range training/practicing at protecting my family, or introducing someone new to shooting. 
I don’t think I’ll have to deploy out of any vehicles with a 10.5 upper. I’m just looking at one for easy of handling, maybe one day I’ll be able to suppress it, and for sh%$ and giggles. I like the LMT, but have read here that they can be picky with non-mil pressure ammo. Given the current rising costs and availability, I would be happy with an upper that would run well on .223 pressures. I would like a 1x7 twist. I know the LMT can be made to run with different buffers, etc. So I am by no means ruling that brand out, and it’s probably what I will end up with.
All that said, for those that have depolyed a 10.5 in whatever way, please continue to educate me, as I don’t know much at all about them, and have not had the opportunity to use one at all!
-RD62
P.S. Please excuse both the length of my post and my public school spelling. Thanks for reading!