Not only am I upgrading one Bushmaster (Yes, I own TWO and I don’t want to hear it.) but I just ordered a BCM upper for the other. I have a possible buyer for the BM upper being replaced but if that falls through I’ll just keep it for a plinker. The other BM getting upgraded has a new BCM bolt carrier and I also upgraded the bolt with a BCM upgrade kit. In addition I have JP springs in the trigger, Ace skeleton buttstock, Vortex FH and MOE rifle-length hand guards for it. Neither will be an SR15 but they will do for a 63 year old Marine that first shot an M16, a couple of weeks before I left for the RVN in 1968.
This shit is a disease !
:dance3:
Well over 100 views and nobody has seen fit to “Show me the error of my ways.”
Maybe I did something right. 
(Or not…)
You’re on the right track by beginning to sell them; even if it’s piece by piece.
Replacing the BCG is a good start. Castle nut staked? Chamber need to be reamed? Twist rate? Feed ramps?
Tell us about the BCM upper you ordered. I’d personally order a blem’d BCM lower to go with that upper, but I’m sure the BM lower will work fine.
Good work, now let us know when you replace the other one! 
cool, glad to see that you didn’t feel like you had to go out and buy the best and baddest to have a good rifle. Thanks for your service, S/F
I’m not telling a 63 yr. old Marine, that he did shit wrong!! Thank you for your service! Which BCM upper did you go with??
BCM upper is a 16in M4 Profile and on the upgraded BM, the Ace stock is like an A2 so no castle nut. Feed ramp and chamber are standard BM (circa 2002) quality. I’m taking this one step at a time and I will most likely deal with the lowers later. I have an LMT BCG on the way for the BCM upper and the BM lower it will go on already has a MAGPUL UBR.
Thanks for the comments and encouragement.
There’s nothing wrong with a BM lower generally speaking.
I have never had a problem but the triggers aren’t the best. One lower has JP springs in it and I have a set for the other one so that will do till I decide on a major trigger upgrade.
My first AR15 was a Bushy, and it had a tight magwell. Most G.I. mags wouldn’t drop free and had to be withdrawn manually. I sent it on its way years ago. I’m sure it made someone happy.
I haven’t had that problem in either of mine but both are '02 models so maybe they were a little better nine years ago. Overall, I can’t complain about either but I am not what you would call a “high round count” shooter. I just decided that my SHTF, “zombie killer” or whatever rifle should be more reliable. After reading many threads here (as recommended) I started on upgrades for both of my BMs that will, hopefully, result in much better rifles, no matter what the use.
The triggers on all AR-15s leave a little to be desired. My bone stock shotgun has a better “feel.” Never been to a rifle match though so -.-
At my age, I’m not likely to start competing in “three gun” or anything similar but I did find the JP springs I put in one of the BMs made a definite better feel.
You’ll be just fine with a new BCM uppper and the lower spring kit swapped out. Enjoy!