AG Disaster - Advice needed!

I am in terrible need of help. I've brewed three AG recipes, I hit the OG spot on during the first recipe and I've missed by .020 on the last two recipes. I was trying to brew the DFH 60 min IPA clone. The recipe is as follows:

13 LB US 2 Row
6 Oz Amber Malt

.75 oz Warrior Hops added continuously starting at 60 min (ends at 35 min)
.50 oz Amarillo Hops continuously added starting at 35 min
.50 oz Simcoe Hops continuously added starting at 30 min
.5 oz Simco (Dry Hop)
1 oz Amarillo (Dry Hop)

Used two vials of WLP001 - California Ale Yeast (Didn't have time to make a starter)

My expected OG was supposed to be 1.071 based on 70% efficiency. I ended up with an OG of 1.050.

This is a quick summary of my mash and brew day. I am using a 48qt cooler with a SS braid. I had the grains crushed at my LHBS and mashed at 152 F with 4.15 gallons of water (stirred thoroughly). After holding the mash at that temp for one hour I drained it off into my brew kettle. I also tipped the cooler to make sure I got every last drop out. I added 3.6 gallons of water for a batch sparge and raised the temp to 170 F (stirred thoroughly). I drained that off into the brew kettle and proceeded as usual.

Also, I added to vials of yeast and it's almost been 24 hours without any bubbles from the carboy so I'm growing a little concerned. This has been by far the worst brew day so far so I'm hoping someone can provide some insight. I want to write it off and just say the hydrometer might be broken but I tested it in water and it's only .005 off which is also reflected in my OG. Please help!

Quick question, what temp did you take the gravity reading? Maybe I'm blind but I didn't see you mention. Temp effects gravity readings with a hydrometer.

Kinda hard to tell from the info as it seems you did everything the right way. My initial guess would be either a poor crush from the LHBS or dough balls.

No bubbles means nothing, especially after 24 hours. Give that time. Being so far off on your intended OG, with your hydrometer checked, would lead me to believe the crush is bad.

Could be you didn't account for temp in your hydrometer reading, too.

How sure are you of mash temps? Accurate thermo?

The temp of wort when I took the hydrometer reading was about 80 F which shouldn't make too much of a difference.

One interesting thing is that the I bought my grain from another LHBS for the last two batches which might be why the efficiency is so bad but I can't believe that it would make a difference of .020. It just doesn't make sense.

There weren't any doughballs, I stirred extremely thoroughly. The themo seems to be fairly accurate, usually within a degree or two.

You would be surprised what a good milling can do to efficiency versus a bad milling. We just bought a mill here and I had the best efficiency ever on my last batch. I avg 80%, this time close to 90+%.

Also, give the yeast some time. I wouldn't start worrying about that until a good 4 days into letting it sit. The gravity shouldn't effect lag time. Not a low gravity anyways.

Did you do anything to confirm starch conversion? Iodine or whatnot?

No I didn't do an Iodine test or anything. I don't know if my hyrdrometer is broken or what. Like I said, I tested it in regular tap water and it was off by .005.

The reason I suspect the hydrometer is that the OG was supposed to be 1.071. For this specific reason I bought two vials of WLP001 (didn't have time to make a starter). I would think that fermentation would start in less than twelve hours if the OG was less than 1.050 especially if I pitched two vials.

Am I right in this thinking? Any input?

Maybe the water minerals (Ca+, Mg+ specifically) aren't in the optimum range, especially if your water has a high pH. My efficiency went up 15% when I started adding gypsum to bring my Ca+ in the 100-150 ppm range.

Check the crush (next time) by visually inspecting to make sure that each grain is well fractured. You could even take a look at the spent grain?

You are only 24 hours in, the yeast may need more time to "catch".

Rather than two vials at like 7 bucks each, you may want to try a pack of 05 dry yeast for like 2 bucks...JMO...but your $ so whatever.

Fermentation has started and it's been about 48 hours so I think everything is fine. I appreciate all of the feedback and suggestions. Next batch I'll check the crush and I also will be checking the pH of the water. I don't know a whole lot about water chemistry and how it effects the mash particularly with each style. I've read a bit about it in John Palmer's book but it looks like it's time for another refresher. Thanks!

Taking the gravity reading at 80F would account for 2 points, so you only have 19 left to find.
You say you got 70% on your first brew, but much less on your subsequent brews. What was the gravity of your first brew? As the OG increases, your efficiency tends to decrease.
Did you stir the wort really well before taking the gravity reading? If not, and you took the gravity reading from the top of the wort, you will have a low gravity, as the first runnings (with a much higher gravity) will still be sitting on the bottom. If this is the case, your gravity will be much higher than what you read, but you needn't worry, as the yeast will do the mixing for you.
If you did mix the wort well enough, then the grain crush or water chemistry could be the culprit, but if you got good efficiency on your first brew, it sounds as though your water is OK if that first brew was a similar color to the two later brews.

-a.