Increase tonearm mass to match low compliance cart

I have a Rega RB250 which has an effective mass of 11 grams.
I want to try a Denon DL-103R cartridge but the 5cu compliance
of this cart doesn't match with the tonearm mass.

I heard I could use brass bolts to affix the cart to arm, the weight
of the brass increasing tonearm mass to nudge resonance into
acceptable frequency range.

Has anyone tried this? I hear Denon's compliance specs might be
lower than reality. I'm a newbie, can anyone recommend an effective
mass that will work well with the DL-103R?
Binar, there have been many posts concerning the 103R's advertised compliance. Most believe it is higher though still a LOMC. I've used the 103r with a RB250 and RB300 with great results. You should be just fine without doing anything special.

I do recommend looking up TWL's tweak which uses some fishing weights as a means to improve stability of the Rega arms. Very cheap but very effective tweak.
I've learned a little more about this issue.
The RB250 has an effective mass of 11g, the
DL-103R weighs 8.5 and has a compliance of 5cu.

So, the resonant frequency of this combo according
to the formula I've found is 16.1 Hz, which is
out of the safe range of 9-14 Hz.

Wonder if that 2 Hz will make a audible difference,
even if subtle or indirect? I'd need to increase
tonearm mass by 7g to get into the window.

In deference to the assurance of Dan_ed, I wonder
what the best way to add a quarter ounce to my
cart/arm is? A metal shim? Brass bolts?
Hi Binar

Your calculations are correct, but a DL103 compliance is higher than 5cu/dyne. A number of posters on the vinyl asylum had tested them and I believe found it to be around 12cy/dyne.

In short, it will work well with your RB.

If you are skeptical and want to add some weight, I suggest you use some blue tack.

Do not read too much into Denon's compliance number. If you do a search at Vinyl Asylum, there is a general concensus there that Denon's number is not particularly accurate and that the real compliance number is closer to 9cu. A member there has measured the reasonant frequency of his 103R in a 10.5g SME V to be just under 9 and many people feel that the Denon works well in many medium mass arms as well as those with higher mass.

Try it as it is and see how you make out. If you feel compelled with adding mass to your arm, I'd suggest using blu tak on top of the headshell and not adding more than about 3-4 grams to start off with.

Hdm and Pauly are correct, and so is Dan_Ed. You'll get a noticeable, audible and enjoyable improvement by adding TWL's HIFI mod to your arm, especially with low-medium compliance cartridges like a 103R. I know. I've done it.

Here's the thread. It's well worth the read. TWL's mod does exactly what he described.