I have a bunch of 40 grain Blitzking bullets and I am wanting to try them in the AR, 1:7 twist.

I know it's normally a try it and see deal but don't want to bother if the general consensus is don't bother it doesn't work 80% of the time.

Has anyone this and had good luck or am I wasting my time?

in a bolt action, with a one in 7 twist, I've had no issues with the 40 grain Plastic tip bullets in the 223.
Whether from Sierra, Hornady or Nosler. And I use them on small pop bottle or water bottle sized sage rats, to distances of 250 yds or so. They hold up to 223 speeds out of any 1 in 7 twist barrel I've used them in...

and the twist doesn't negatively effect accuracy of the 40 grain Bullets.

I could not get the lighter bullets to shoot worth a crap. I tried 40, 45, 50 with no luck. The 55 gr. shoot real good, so I stick with 55 gr and am very satisfied. I have a bolt action that loves the 45 gr. bullets. It is a crap shoot really.

Not worried about accuracy so much as I was concerned with them coming apart in flight.

I’ve always wondered, if 40 grain bullets shoot accurately and hold together in fast twist battles, why are slow twist barrels made?
Itsprobably obvious, but…..

Who makes slow twist .223's these days? I'll guess someone does.

Lots of slow twist .22's out there, made before everybody just had to have fast twist stuff. My 30 year old Browning Low Wall .223 is a 1-12 and it handles beautifully anything I feed it which happens to be 40-55 stuff because I have absolutely no need in my life for longer/heavier bullets to reach way-to-hell-and-gone out there.

Shot many thousands of 40gr Blitzkings through an AR and had no blow-ups. my AR's were 1-8" and 1-12" twist barrels........5 and 6 groove barrel's

Only time I have seen 40gr Blitzking's blow-up in flight is with 22-250 and 220 Swift with 1-8" twist 3 groove barrels, with 223 speeds you are safe with 1-7" twist even with a 3 groove barrel.

Having owned a few AR barrels and shot many 40gr BK's a 1-12" barrel is more accurate with this bullet........WOA !!!!

White Oak makes a fine 1-12" AR barrel

Several others. Think Iay have even see a 14 twist offering.

Assuming still made because that was the norm 30+ years ago and some still have no need or desire for anything faster. Even Savage went to a 9 twist 25+ years ago.

Also still several super fragile bullets offered. SX, Blitz Varminter and TNT.

TNTs aren't that 'super fragile'..... at least not in most of my rifles.

X-Caliber even offers a 16 twist.

6 of the Blitzkings made it to a 40 yard target earlier. Will keep on shooting these on critters now.