I have the 5.45 carbine and just wondering what pound trigger is installed in that and what is a nice all around trigger upgrade you might recommend
If you want a good trigger for your rifle you might consider the Giessele SSA. The trigger will be very reliable and also should feel very pleasant compared to a standard GI model.
Also welcome to the forum 
Sorry for the delay, I guess my email notification isn’t working.
The 545 carbine comes with a standard mil spec type fire control group with an extra power hammer spring. The pull weight is usually somewhere around 6-9 pounds due to the extra power hammer spring. Using a standard hammer spring will lighten the pull weight and should be ok with the surplus ammo, the extra power hammer spring is just a little more insurance if you will when shooting surplus with harder primers. I have also used the Giessele as well as the JP with surplus with no issues. Both of those are quality triggers that will lighten the pull weight and offer a crisp break. The Giessele is probably the nicest 2 stage on the market, and the JP EZ trigger is arguably one of the best single stages triggers.
Thanks for asking and welcome to the forum too!
Dave