What FPS were you loading the 300BLK to?  Sounds like issues with underpressured ammo.  I don't shoot 300BLK, but I shoot with many who do.  I'll ask them about combinations of gas length (I assume carbine), springs, buffer, etc. 

Yeah, recoil on most AR15 calibers aren't bad at all.  I haven't shot the wildcat stuff like 6.5, 6.8, etc, but I can't imagine them being too bad.  5.56/.223 is nothing really.  I haven't shot a rifle length gun in a while, but I would really love to own a rifle length upper.  When I was thinking about getting into service rifle matches, I was close to getting a basic (irons only) upper to shoot those competitions.

I don't know exact feet per second but I was having problems with everything except a few brands of factory supersonics. I ended up opening the gas port to 0.125" and it helped but it still doesn't run most factory or reloaded subsonics. Maybe I need to mess with it more or find another powder but I've basically thrown in the towel for now and have been looking at getting a pistol length gas Barrell for it.

I don't know exact feet per second but I was having problems with everything except a few brands of factory supersonics. I ended up opening the gas port to 0.125" and it helped but it still doesn't run most factory or reloaded subsonics. Maybe I need to mess with it more or find another powder but I've basically thrown in the towel for now and have been looking at getting a pistol length gas Barrell for it.

Thanks for the feedback.

I don't roll my own, so that has kept me away from the 300blk.  Lots of them in competition though.  I'd also look at 300blk harder if going suppressed was an option. 

Thanks for the feedback.

I don't roll my own, so that has kept me away from the 300blk.  Lots of them in competition though.  I'd also look at 300blk harder if going suppressed was an option.

I don't bother rolling my own subsonics. What's the point? I get better accuracy with supersonic loads, use cheaper pistol powder and lighter bullets which cost less. There is no upside that I can see to load subsonic rounds. Now, if suppressors became legal for use I would start testing subsonic loads.

I don't bother rolling my own subsonics. What's the point? I get better accuracy with supersonic loads, use cheaper pistol powder and lighter bullets which cost less. There is no upside that I can see to load subsonic rounds. Now, if suppressors became legal for use I would start testing subsonic loads.

It is my understanding that most competition shooters are rolling subsonics.  Just like the handguns loads, they are tuned just above minimum power factors or function. 

It is my understanding that most competition shooters are rolling subsonics.  Just like the handguns loads, they are tuned just above minimum power factors or function.

That's my understanding, too.

Now that you said it. 

I've never tried the Vltor A5, and you and a couple others have mentioned that.  May have to try one of those. 

On a new build the A5 is my option.  If a system comes without it, not sure if many would notice the benefit that much on a swap out.  Just depends on the system no two are generally the same even if they are the same parts in a build.

Interesting you mentioned the lightweight/pencil barrel thing.  What about the ltwt barrels don't you care for? 

For the pencil barrels, I don't care for the shift in accuracy when the barrel gets heated up.  Most shooters at KKHD from a bench or when shooting up close, say in the lower combat ranges may not shoot hard enough to heat the barrels or may not have an accuracy requirement when the barrel is heated up that makes a difference in their shooting.  However, for myself every barrel in this "pencil type" category that I have tried (tried most of them) when I heat them up, I cannot hold an acceptable unsupported group size at 50 yards with given time constraints. 

I generally tend to use the modified Navy qual as the standard to compare by and I run the qual cold and after the barrels are very much heated up for comparisons.  I may also do 100 yard groups after getting a barrel pretty darn hot.  Now is this shooting condition or standard that many other people will try to adhere to?  Maybe not, but I see a noted difference in performance that I personally find an unacceptable trade off for any advantages that the weight savings offer. 

Granted some may say that this isn't a precision weapon or those situations are not a concern for them and that is OK as my requirements may not be the same as the needs of someone else.

There seems to be sweet spots on how short a barrel you can go.  I haven't read or thought about it in a while, but I thought it was 10.something". 

We have run Colt 14.5's, Colt 10.3's and LMT 10.5's that were dead nuts.  Dwell and unlocking is a tricky thing and some have compensated with certain extractor spring type set ups, but not everyone gets it correct.  The general consensus is anywhere from 11.5 to 12.5 and in the past and for certain manufacturers there were or are certain length in front of the gas block considerations suppressor set ups.

On a new build the A5 is my option.  If a system comes without it, not sure if many would notice the benefit that much on a swap out.  Just depends on the system no two are generally the same even if they are the same parts in a build.
For the pencil barrels, I don't care for the shift in accuracy when the barrel gets heated up.  Most shooters at KKHD from a bench or when shooting up close, say in the lower combat ranges may not shoot hard enough to heat the barrels or may not have an accuracy requirement when the barrel is heated up that makes a difference in their shooting.  However, for myself every barrel in this "pencil type" category that I have tried (tried most of them) when I heat them up, I cannot hold an acceptable unsupported group size at 50 yards with given time constraints. 

I generally tend to use the modified Navy qual as the standard to compare by and I run the qual cold and after the barrels are very much heated up for comparisons.  I may also do 100 yard groups after getting a barrel pretty darn hot.  Now is this shooting condition or standard that many other people will try to adhere to?  Maybe not, but I see a noted difference in performance that I personally find an unacceptable trade off for any advantages that the weight savings offer. 

Granted some may say that this isn't a precision weapon or those situations are not a concern for them and that is OK as my requirements may not be the same as the needs of someone else.
We have run Colt 14.5's, Colt 10.3's and LMT 10.5's that were dead nuts.  Dwell and unlocking is a tricky thing and some have compensated with certain extractor spring type set ups, but not everyone gets it correct.  The general consensus is anywhere from 11.5 to 12.5 and in the past and for certain manufacturers there were or are certain length in front of the gas block considerations suppressor set ups.

Interesting on the A5 system.  While I'm certainly interested, I can see what you mean about noticing benefit.  Probably a case where things are so subtle, that many (including me) probably won't notice the difference.  Like when I first got into throwing darts.  A couple of my buddies had their own darts and were telling me about how they liked this or that.  Didn't really matter to me at the time.  But then as I started to get better, my throw more consistent, I started noticing the differences and started to figure out what was the right fit for me.  Similar to the process of finding out what works best for me with guns.  While it's fun to go through that process, at least for me, it can be an expensive process as well as humbling while one is still relatively early on in that process, like me.   

Got it on the pencil barrels.  That you can see the effects at 50 yards, to the point where it gets to unacceptable group sizes is interesting.  I would have thought one wouldn't be able to notice a spread until further, like 100 yards at least and probably more.  However, like you said, it depends on the individual's requirements and standards.  And of course baseline capabilities, which in my case I might not be able to tell if it's the gun or me to be quite frank.    

My second AR was the BCM with light weight barrel.  That was part of my normal weight vs light weight head-to-head comparisons.  Other than the overall weight of the gun, I haven't really been able to shoot the BCM side-by-side with my other ARs with normal weight barrels.  I haven't looked at the weights in a while, but if I recall correctly, the weight savings is about 3-4 ounces between Gov't profile and most lightweight barrels.  Yeah, for those who have to carry the gun for hours on end, I am sure that can make a difference.  Hell, I can feel the effects of a heavier gun after a 2-3 day carbine class.  That said, in my case, the 3-4 ounces probably isn't much.  Just one of those things that I always wondered about and as I settled into my AR preferences, one aspect that I haven't gotten around to testing for myself. 

What I was thinking with regard to a precision AR was something with a magnified optic, like DMR/SPR type rifle.  As opposed to all of my ARs are 1x red dots.  I am not trying to shoot 1 MOA groups at 100 yards all day.  However, that doesn't mean that I shouldn't push myself to get better accuracy/precision with what I do have.  Maybe just an excuse that I've been carrying around to not have to put in the work on that regard.  It's easy to punch holes in paper at 15-20 yards, but takes a lot more discipline to work on accuracy and precision.  Like you said, depends on the individual's requirements and criteria on what is acceptable performance. 

A bunch of the guys I shoot with and have taken classes with in AK have SBRs with suppressors.  So jealous.  I think mostly of them went with factory SBR uppers (DD and Colt I think) and I don't recall them having issues.  Though I have read about many having issue with tuning their SBRs, but not sure if those were factory uppers or builds.  I would love to have a suppressed SBR one day, but I just tell myself that I'm saving money due to them not being legal here. . .