I live in a part of Arizona known as having some of the top 1911 gunsmiths in the country, Yet not many of then know about one of the best kept secrets for 1911 accuracy. I once talked to Jim Clark of Clark custom guns and he told me that by using this method he could make almost any 1911 shoot 1 1/2'' groups at 25 yards with factory barrels except Springfield 1911's because of many of their two part barrels. My poor Springfield! The Secret. Proper barrel lug and reciever lug alignment. Some gunsmiths tig weld the lugs and machine them not recomended by most.. Other companies such as Brownells offer oversized lugs on some barrels so they can be machined for accuracy. If you intend to have to have your 1911 made accurate ask them if they know how to do this. If they don't know what your talking about, or say that it will not work or help, just say goodbye. This type of work is usually done by gunsmiths that do work for IPSC shooters. The barrel lugs must fit the top lugs also known as the reciever lugs properly, or the lockup will also not function well. Each time the gun is fired it must go back into proper battery. The best way that I can describe this is that the lugs must be set up in the correct horizonal alingment with the barrel bushing to create the best possible accuracy. Have you ever bought a very expensive match grade barrel for your 1911 only to see it not improve your guns accuracy! I can say only one thing Barrel lugs! This is almost always the problem. I'm just trying to save some of you guys out there trying to customize your 1911's a lot of time, grief and money by having it done right the first time. In building powerful 1911's like a 10mm, a 460 rowland or a 40 super the upper and lower lugs are not often made of strong enough steel to handle the caliber. If your lugs are not vertical any longer and are starting to slant you probably just destroyed your barrel and receiver on your 1911. Try to find a 1911 that is made from billet or forged steel. If you want to make a high power caliber change you have to make sure that your 1911 is built strong enough to handle it. Stay away from cast 1911's for high pressure cartridges. If the gun is not built strong enough you can get barrel lug setback, (SLANT) or break parts of them off . Also look into slowing down your slide speed. Use Heavier recoil springs, a compensator, and a EGW 10mm firing pin stop. Using a stainless steel 1911 also helps by slowing down the slide speed. The difference between a stainless steel 1911 and a regular steel 1911 recoil spring for comparable loads is 18lbs for stainless and 24lbs for regular steel.