I am posibly looking to buy either a 22 converison for my SBR or building a whole new upper (only need barrel and bolt) for a dedicated 22lr upper.  I called spikes tactical and they said the conversions will more then likely need tuning.  What exactly does that mean?  I have a feeling it means different tension springs and such but im clueless to it.  Can anyone help me out with this?

i am about ready to pull the trigger on a dedicated upper but i would like to know how hard it is to "tune" a conversion thanks!

mike

Spike's has a whole thread about this in their forum.

You tune it by cutting coils off the spring in the kit. They say not to cut it down to less than 7.25" (i believe) I have a nearly new carbine, and had to cut alot more off mine, and even did the '15 min trigger mod" to my hammer and trigger springs to help aid in it. That said, it is starting to runn pretty consistent, and I like that I can just slam my regular BCG back in, and be tap out a couple 5.56 rounds.

Before you do any trimming, run some mini mags through it to get everything working. The shorter the barrel, the more tuning. Spikes did a great job designing it to work with Fed Bulk ammo. Problem came when Federal started slacking on thier product. Fed Bulk is so inconsistant, it will cause problems. You can hear the difference between rounds. Also, I had to trim some off the feed lips of the Black Dog mags. They were too long for the ejector to work properly. I use a RRA NM 2 stage trigger without problems. Some have had them break. Others report "notched hammers cause problems. I've not experienced any of those. Tom at Spikes will give you all the help you need. It's not as bad as it sounds. I get maybe 2 FTE's out of 300 rounds.

I am going through that process rights now, today was the first day for my Spike's Tactical conversion.  First mag went great then started to get stovepipes.  After about 300 rounds it became a fairly consistant once every 35-40 rounds.  Cleaned it and trimmed 3 coils off, next week I will try again.  BTW BDM and CMMG mags are both very good, wish I had just bought clear/smoke ones though - like to see how many rounds left.  

Buy lots of magazines, you will use them.  

Now it works flawlessly, I don't know how I got along without it.

You can do what I did. When I ordered my ST-22 upper from Spike's Tactical, I requested that they test fire it with CCI Minimags so I wouldn't have any feeding issues when I received it. If they did have any feeding issues during the test firing stage, I'm pretty sure they polished the chamber and feed ramps to get it running so I wouldn't have to worry about it on my end. If you're planning to do your own build, I believe you can also send them your upper of your choice and have them install the barrel and .22LR bolt and test fire it. You can go to Spike's industry forum here for .22LR semi-auto tuning.

+1 - Federal bulk ammo has gotten very inconsistent - I can hear and feel the difference - the bolt sounds like it's coming back in stages on bad rounds. I've also had a really bad batch of Federal Automatch which would not function - my friend used it a military training/match rifle that shoots virtually anything and it strung veritcally. Federal bulk even had FTE in my old Nylon 66 - an absolutely reliable autoloader.

I've had little or no problems with all the different triggers and hammers in my lowers.  RRA NM, Timney, Accuracy Speaks, standard hammers - notched and unnotched.  Strangely I've had problems only when going to lighter hammer and trigger springs - just the opposite of what many others have experienced.

YMMV

"Tuning" is one of those vague terms that could mean any number of things.

There's an excellent tutorial on polishing the Ceiner kit here.  Problem is that the page is often not available because of hit-limits imposed by the host.  If so, PM me.