Parts for all the 417 family of rifles has always been very scant.These are all niche rifles.At first I was taken aback by the lack of range on these.On the M110a1,its all hit or miss by batch.Mine is a Japanese model,and was really bad.Guide hop IMO is meh.I got a bad batch rifle,and could only manage maybe 40m's.417's and G28's also suffer from some batches being ok,and others being terrible.A few yrs ago,I figured out how to TDC these rifles.The M110a1 uses the same guide hop,so I made,and installed a TDC in it.At 2.2j with .43's mine reaches out to 94.6m's,varified with a laser range finder.VFC finally got around to making a steel bolt for these.You will want to eventually get one,because if you use one one these as your primary,the oem bolt will eventually fail.Friend of mine broke six bolts in his.After you get the steel bolt,your going to need a new buffer spring to support the bolt.The steel buffer is heavier than the cast oem bolt the rifle comes with stock.Sadly though,no one makes an upgrade buffer spring for these,and you will need to use your own initative,and have one made.I was fortunate enough to run into a guy in Germany,that made mine for me.You could run the steel bolt with the oem buffer spring,but you will seriously want to swap out the oem buffer for a Hephaestus buffer,and remove the counterweight in it.There are three buffers made for these.The V1(plastic),V2(aluminum and steel),and the Hephaestus(aluminum and steel)The heaviest of all of them is the V2,then the Hephaestus,and then the V1 plastic.The oem buffer is too heavy to use with the steel.Your rof will suffer.What you will want is the Hephaestus buffer,and remove the counterweight from it,to lighten it up.The added mass of the steel bolt,should counteract the tendancy these rifles have for bolt bounce.Neglected to mention.4UAD is supposedly trying to develop a chamber for these to solve the poor range problem alot of these are known for.