I would like to have ADCO or AR15Barrels (if I can ever get ahold of him) turn two of my barrels down to lightweight profiles both in front of and behind the gas blocks. The first barrel is a BCM 16" BFH and the second is a Rock 16" for an LMT MRP. Will I see any negative effects over time due to this machining process?
I dont mind a loss of 1 or 2 MOA, these are carbines that rarely get shot at more than 300 yds, and if they do its always on big plates. If I con continue to hit Able’s out to 500yds, then no biggie.
ETA: Trident has, in the past, mentioned that it may harm the barrel harmonics on the LMT barrel to take her down to lightweight. Im harmonic ignorant so if someone can expand on this that would be great.
I have looked into it for one of my bolt guns and asked several smiths about it. Most say if its done right there is no effect on accuracy. With a bolt gun I would have to redo my hand load as the harmonics would be diffrent for sure.
Im not a handloader, so the PRVI or PMC should do just the same then.
The MRP is not really for sale, but Ive just been really liking my lightweight setups and damn if that thing doesnt feel so much heavier after shooting my MOE BCM.
Ya it sure does feel heavy some times but that just means its a better club when your out of ammo. I have the 16" DI and Piston and the piston makes it even worse. My wifes has a DD middy, light weight and its like a toy.
I added a diffrent shoulder excercise to my workout just for shooting that I saw some BOPA guys doing in Brazil on military channel it has helped alot.
Let’s put aside the barrel harmonic’s given it very nuance and they will always be affected by any kinda substantial re contouring, dimpling, fluting, etc., and it’s in my knowledge impossible to say if it will positively, negatively, or hold par in it’s effect.
What isn’t as hard to calculate and forecast is what the properties of barrel heat due to the barrel’s accuracy and how this relates to barrel re contouring. The end user has to debate if the weight shavings supersedes the ability to maintain accuracy once the barrel gets to certain temp’s which will be well accelerated(in this case meaning less rds. fired before it gets to temps that degrade the accuracy of the barrel) already by the thinner profile and less material to dissipate the generated heat from firing.
It sounds like your GTG if you plan to use the folks you mentioned…I know many folks who have had both those outfits perform work on MRP barrels and never heard them complain or say they regretted doing it. I also suspect very few folks really push their gun that hard to even calculate before and afters in the accuracy dept. Like you said, your willing to give up accuracy anyway and so if your accounting for a slight reduction in your decision than I see no reason to not do it.
I would second what Trident said. I have a bbl turned down by ADCO to featherweight profile (0.590) before and after FSB. I haven’t shot it much as this was intended to be my wife’s rifle. Zeroing it showed about an inch groups at 50, but groups open up after one mag of moderately paced fire.
in all the discussions on barrel dia and it’s effects that I have seen, one question stands out in my mind – unless you have a straight profile and given that dia changes over the length of an AR barrel, how can one say for sure that any changes to the profile beyond the gas block will make a predictable difference?
those talking about “lightweight” profiles heating up or vibrating, etc., are ignoring the reduced dia behind the gas block, right???