There should be a bevel on the fact of the extractor. That bevel is to cause the extractor to spring out and over a shell rim. If you are using steel cases there can be a problem because the shell and the extractor are both made of steel and the slippage you ordinarily get with brass is lacking.
When any Mauser or Mauser copy is made right there is no problem with single loading. That’s something the “Real Experts” try to tell you so you’ll think they have deep and special knowledge.
I have been a gunsmith now for over 45 years. I have made so guns on Mausers (as well as Springfields, 1917 Enfiends and several other actions that copy the Mauser system) that I lost count of them probably 25 years ago. I have made them for several prestigious clients including 1 of the “big names” of London. I assure you that if the action and extractor are set up correctly they are not going to break
If yours is not working there are only 2 reasons.
#1. The extractor is not beveled correctly. If you had a CZ527 action barreled for a 7.62X39 and it had a 223 extractor installed, that would cause that problem exactly.
#2, Steel case heads are hard enough to “bite” a bit on the extractor bevel and not let it slip. This is again a matter of having the correct polish and angles stoned into the bevel.
Let’s look at a bit of logic here.
Let us look at the extractors on a Weatherby, a Mosin Nagant, a Remington M700, a 1903 Mannlicher, or an M91 Mauser and then let’s compare them to the extractors on a Krag, A Springfield 1903, a Mauser of the M93, 94, 95 96 or 98 type, a Ruger M77, a pre-64 M70 Winchester.
The average depth of engagement of a shell head is about .026” to .028” on a rimless shell and about .032 to 040” on a rimmed shell.
So we are safe to assume NO extractor will ever have to flex more than .040” to get over the rim of a shell.
Now let’s also assume we are talking about good quality spring steel used in every example, and also correct hear treatment.
(Yes I know, there are examples of poor steel and poor heat treatments that were used from time to time, but that is a completely separate issue. Poor quality is not something we can get around with “careful loading” nor should we. If you have an extractor that is poorly made replace it instead of babying it)
If we go back to 6th grade geometry we can see easily that is we flex 2 pieces of steel at one end .040” but one piece of steel is 3” long and the other one is 1” long, the one that is 3” long is going to have 1/3 the stress on it than the 1” piece is going to have, and that only if we do not take into account the fact the springs stack so the stress is a compound equation. Real springs stress exponentially.
So why would the Mauser be in such danger of breaking when the Mannlicher and the Weatherby and the M700 are not? The 700 uses a semi-circular clip as an extractor which when measured over the outside curve is less than .600” long. Yes, they do break now and then, but I don’t hear the outcry about how often they break. I have been gunsmithing for over 45 years now and I have probably replaced about 100 to 130 Remington 721, 722 and 700 extractors because of breakage. I have replaced exactly 2 Mauser extractors and both were not because they broke, but because someone bubba’d them up.
Anyway, without belaboring the point farther, you should be able to single load your CZ. If you can’t something was not fitted or polished correctly at the factory. You should probably call CZ USA and ask them, but I’d bet you they will have you return the bolt to them for repairs and that will solve the problem.