I was shooting my Bushmaster with my CMMG conversion bolt at 50 yards. Using Winchester ammo, I was grouping just under 2" - not too shabby. I ran out of Winchester, the broke open a box of Federal bulk. Shot a couple of cards revealing my groups had grown to almost twice as large! I verified this was not a fluke by shooting some more groups. Moral of story - Federal bulk sucks in my rifle! Fortunately, I had a pack of CCI minimags, of the roundnose type. Shooting a couple of 50 yard groups with CCI Minimags - normal service is resumed - thank you Lord. Actually, the CCI's were damn good at 100 yards:

The smallest groups is 3", the largest is 5", all were shot with open sights.

My 1:9 twist barrels were most accurate with Aguila 40 grain round nose plated Super Extra using Ciener or CMMG conversion.  In my barrels the Aguila seemed to have fewer fliers.   The Aguila SE is also very accurate in a friends CZ V-22 which has 1:16 twist.  Seems like you never know how a particular round will work in 22's till you try.  The Aguila actually shot better than Wolf MT, WW sub sonics, Ely's or Remington standard velocity.

Rimfires are notoriously ammo sensitive. Until you get into true Match ammo (SK Std+ or better), what one rifle may like could be completely different than the same model with the next S/N.

Absolutely, been saying this for years.  

Sometimes you run across a rifle (whether AR with a .22 conversion kit or just a regular .22 rifle) that really "likes" some .22 ammo that many people regard to be the worst ammo out there.

My Win. M52B like Remingtion Thunderbolts.

My XM177 Clone like Remington Golden Bullets.

Buy different brands/bullet types and try them out for functioning and accuracy.

I was really surprised with the difference in the ammo, even those with the same weights. I'm glad to find out that I have a couple of brands that work well in my conversion bolt and rifle. I have read a lot of posts of people getting 4"- 6" groups at 50yds with their conversions. People should really take the time to test out what their rifle likes. My brand new box of Federal is relegated to my pistol, so it won't go to waste.

Try the Federal Match Target bulk  box from WalMart.

I'll buy a small box of that in the future to see how it works, thanks for the suggestion.

my stainless CMMG kit in a 14.5in. BM does 2 to 3in. groups at 30meters with every brand that I've tried & thats with a 3X9 scope & match trigger ..the wild groups & the fact that it spits smoke & residue back in the upper from the gas tube forced me to buy a 15/22...that's what I told the wife anyway..... oops ...take care ....Kent

CMP Aguila - which barely runs in my Kuehl - runs well in my Spikes and shoots as well as Eley Target.  Wolf MT - which is great in my bolt .22s and Kuehl - shoots "patterns" in the Spikes.

Most Blazer is so-so function wise in my AR .22s but the last few boxes my friend gave me - that particular lot - functions and shoots well.  

My old Martini club rifle will only shoot Eley.  I tried RWS, CCI Green and some Federal Match...no where close to the Eley.  Wolf Match did better but not as good as the Eley.   None of my rifles likes CCI Green but all love CCI Standard.  Go figure

Accuracy and function wise across a number of my different .22s - most shoot CCI Standard and CCI MiniMag well.  Blazers are generally okay too in my bolt guns.  Tried a box of CCI AR Tactical - very promising except the recent big run on ammo and guns has cleaned out the shelves here.

As previous posters have said - test a variety of ammo for your .22s.

YMMV

I'm sorry to hear you're getting such poor accuracy from your bolt. With the exception of Remington ammo, I've never had much of an issue with residue in my upper and lower receivers with the other ammo I've used. I've been tempted to buy a dedicated upper, but I'm very happy with the accuracy I'm getting. Like you, I may have to give my wife a cover story to justify buying one in the future though.

Kendak:

Is your BM 14.5 a 1 in 7 or 1 in 9?
People have reported so-so accuracy in the 1 in 7s - some really awful groups.
That said:  My friend has a Colt M4ish upper (that I sold him cheap), 1 in 7 and runs a Ciener kit I gave him.  Says at 50 yds it shoots under 3 inches and he's very happy with it. He runs only CCI MiniMags cause that ammo works in his Kimber .22 1911 conversion.

YMMV

OT:  Now it's off to Thanksgiving lunch - Turkey, stuffing, ham with cherry sauce, baked yams, mashed potato, etc., etc. - will not post again to ARF.com till I recover.  Happy Thanksgiving to all!

it's a 1in9 twist...3" group to me won't get it  ...my 10/22 with Shilen br. will do 3/4"  [10] shot groups at 50 meters with just about any cheap bulk ammo...just got back from the range with the new 15/22 Performance with the [Laney] chamber & shot several 1" 50 meter groups sighting in a Leupold [will have to drop in a better trigger]...ammo used was Fed. HP bulk bought in 1988 at wal-mart <trying to rotate stock]....the open path of the gas tube back into the upper bothers me as much as lack of accuracy & also bleeds off a lot of pressure according to my chrony....I don't believe that the kit will do much better because of several reasons ...insert fit in chamber & bullet jump to rifling being the two most important....but then again I might be to critical because I built varmint rifles for years & if they wouldn't shoot sub MOA I would rechamber & start over...the guns I built in .223 Ackley would shoot 3/4" [5] shot groups at 400 meters or they wouldn't leave my shop.. ...BTW the CCI mini-mag shot about 10" at 50...don't show or tell your buddy any of this if he's happy let him be...take care & Happy turkey day....Kent..

Oddly enough my CMMG 14.5" 1-7 barrel will shoot some decent groups at 24 to 50 yards...with good ammo!  The Fed Bulk stuff from Wally World...forget it! CCI Standard Velocity....good shooting!

I have AR's with 1-7, 1-8, 1-9, and 1-12 twists. Oddly enough using a conversion in them they really vary a lot on accuracy and its more ammo than it is twist rate. Just my own personal experience, YMMV.

I have a selection of at least eight or ten different .22 ammo brands and styles. I use it to test each rifle to find its favorite. Boy does it ever  make a difference!

LOL!  My Spikes upper shoots CMP Aguila and Eley Target around 1" to 1.5" at 50 yards - almost always have one flyer that ruins potential .75" groups.  However - kinda like your experience with CCI MiniMags - my Spike's shoots 3" plus patterns (no consistent group) with Wolf Match.  Wolf Match shoots well in my bolt guns but turns my Spikes into a shotgun..  

As for me - at my age and with my eye hand thing going south rapidly - I'm happy with any sub 2" groups.

I am almost comatose from all the turkey, etc.  Good night and, again, Happy Thanksgiving.