I have a good load for 122 gr flat point lead but wanted to try some lead round nose so I can feed them reliably in my 9mm AR.

HOWEVER

Similar bullet weight 125gr lead round nose bullets are extremely inaccurate out of the same pistol: a CZ75B 9mm.  I am experimenting with different powder loads using Titegroup which has worked great for my other loadings.  I am also looking at seating depth.

Anyone have any insight or advice on this dillemma?

Titegroup is almost universally discouraged for use with lead bullets, AFAIK, certainly for 9mm - it's a fast and hot powder, and can lead to excessive smoke, leading, and resultant inaccuracy, etc.
We're having a discussion on BE about this, and can't even seem to get consensus on use with the better quality coated (Hi-Tek) bullets and TG.

Note specifically on the CZ - it has a short chamber.  Have you checked your physical max OAL on that barrel and done a plunk test with your rounds?  That could also be causing some issues for you..

I have had to shorten the OAL on the TC rounds I use due to this.  It's good to note.

Perhaps I will try some H110 on a few loadings to see if that makes a difference.  I also have a Lone Wolf glock 17 barrel that I can use to test.

I shoot HUGE amounts of 125 RNL out of Glocks with a load of Unique.  It's dirty but works fine.

what other powders do you have available to try with the lead 125? Titegroup is a great powder but it burns very hot and it is not friendly to cast bullets or wax lubes. Might try seating you RN to 1.100 and then trying the plunk test.

If you plan to shoot these out of an AR i would suggest a much slower powder. WSF, AA#7 would be ideal in the longer barrel.

H110 is not a 9MM powder choice. This powder does not lend itself to working up loads. This is the exception to the reduce 10% and work up. Hodgdon suggest it only be reduced 3 percent when working up loads.

Depending on the vendor of the Cast 125gr RN bullet, most commercial casters are using Magma moulds.  
the bullet needs to be seated rather short COAL.  Something about 1.1".  Do not use a Lee Carbide Factory Crimp Die, it actually resizes the bullet and my contribute to poor results and other untold problems.  A regular Taper Crimp die.

Titegroup burns very hot. This combined with most cast bullet lube leads to a lot of smoke when shooting.
More medium burning rate pistol powders are better choices. Power Pistol, Universal Clays if it were available.
VV powders are universally considered as least likely to create excessive smoke.  

Some CZ guns have Polygonal rifling and this may be a consideration when working up your loads?

I use WSF in 9mm with 125 - 147 grain LRN 5" barrel Sig - great stuff!

My CZs do not have short throats. They are CZ-75s and not Bs or newer.






 

 

I used Titegroup for several seasons in IDPA/Defensive pistol under 115 and 124 gr FMJ's with exposed lead bases.  A bit of smoke and a lot of lead fouling, accuracy was very good, but lead was every where.  Unique works very well with the lead bullet weight you use, I also try to use Winchester powders such as 231,WST, WSF and AutoComp because they are lower in flash than most powders.  My go to with 125 LRN is AutoComp followed y 231 and WST.   TG is a poor choice with lead, works but you will breathe a lot of lead vapor indoors.

The OP makes no mention of key factors for shooting lead.

The flat points shoot good the round nose does not.
OK,How are they different?
Diameter?
Hardness?
Lube type?
Are they inaccurate because they are lead fouling the barrel?

There is a lot more to it than just powder and OAL.

If you can find HS-6 its a good 9mm powder. I have loaded 125gr lead cast with both tight group and HS-6 for my STEN sub machinegun. While tight group leaves the receiver cleaner with jacketed bullets the HS-6 produces less leading with lead ones.

In any case I eventually stopped shooting lead in the sten all together because I got tired of the belching clouds of smoke on full auto from the bullet lube as well as the leading from the high volume of fire.

Dont get me wrong I shoot lead exclusively in my revolvers but I just didn't find the juice worth the squeeze in the 9mm.

For 125 gn rn lead bullets I use Unique or AA no# 5. I like no 5 over unique as it is cleaner, meters better, and not as smokey.

My competition loads are 124 grain bayou bullets cast lead coated and titegroup. No accuracy issues but a little Smokey. Other members have had issues from either bullets or crimping too heavily.

Load is 124 gr rn, 1.15 oal and 3.8 gr titegroup.
They are cold sensitive though. When competing at 25 degress, mags had to be kelt against the body to keep velocity up. We normally shoot in 90 degree florida.

There is a common 125gr RNL that a lot of vendors retail that has a thin leading drive band.... easy to over do crimp and mash this band down leaving only the rear band to grip rifling

3.6 gr TG under a 125 lrn at 1.135 is a great load that makes minor pf.