Sorry I didn't get back sooner.
Malted grains contain enzymes which convert starches into sugars. For that to work they must be kept in solution inside a temperature band as well as a pH band.
Some malts have already been through the process of converting those starches into fermentable sugars. This includes caramel/crystal malts, and very highly kilned grains that are essentially cooked until no starch remains (eg, roasted barley, black patent malt).
Various base malts have varying amounts of these enzymes left after the kilning process. Generally speaking, the more they are kilned, the more that some of those enzymes will be destroyed by the kilning process. That means that they have less "diastatic power" than the lower kilned base malts (6 row, 2 row, pilsner, wheat malt).
The "high dp" base malts are capable of converting themselves as well as a measure of external starches, such as those from other adjuncts. As a rough general rule, you can estimate that a lb of base malt is able to convert itself plus about a half lb of adjuncts (ie, corn grits, polenta, rice, unmalted oats, etc). (some can do a little more than others).
On the other hand, Munich malt and Vienna malt are able to convert themselves, but not much more.
Other malts, such as bisquit malt, honey malt, brown malt, etc, have neither been pre-converted nor do they have enough diastatic power to self-convert.
So, you need to ensure that when you convert recipes containing various specialty malts and starchy adjunct, you must ensure that you mash them at proper temperature and pH so that the enzymes will convert the starches into sugars and non-fermentable dextrins. Otherwise, your beer will have a lot starch left in it, which the yeast cannot consume. Also, these starches leave the beer in an unstable state, leaving it open to aging issues and other off flavors.
So, you quoted "160 degrees for 30 minutes" for steeping. That temperature will work fine for steeping grains that have already been converted, but it is possible that the high temperature can prematurely denature any enzymes present in your malts leaving a partially un-converted wort.
I'd recommend you use 152F, which is closer to the middle of conversion range. You'll still get a
good steep, but without prematurely denaturing any enzymes. Besides, it's better to practice controlling your temperature at a range where you have more room above and below if you miss.
There are more details why 152 is a good choice (alpha vs beta amylase activity) but we don't need to go into that level of detail for what you want to accomplish, as the fermentablity of the bulk of your wort is set by the extract itself.