Beersmith setup says I need 8.62 gal total.
Using your numbers, I matched gallons total water needed. My estimated OG was 1.055. Oginme left excellent equipment and use of BeerSmith advice to the OP, so I won't be redundant about it.
I have a 5 gal igloo mashtun. First runnings yielded 2.25 gal of wort.
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Boil time is 60 min.
Earlier in your post, you said actual boil time was 70 minutes. I used 70 and it matched your other numbers. This may indicate your evaporation rate is lower than you have it set for.
You didn't say how much wort you dumped after getting a full kettle?
When my numbers line up with yours, BeerSmith says you need more than a 5 gallon mashtun at liquor to grist ratios of more than 1:1. Does this line up with your equipment?
So, I'm suspecting three things.
1) Total water an boil volume are stated at hot temperatures in BeerSmith. If you're filling your HLT cold, you have to add expansion to that number.
2) You may need to adjust the grain absorption number. This is found in Options > Advanced. The absorption number is subject to change based on how well your malt is milled.
3) If the malt is milled by your LHBS, it may be too coarse for higher efficiency. Many stores have their gap just a little wider than optimal. This isn't anything sinister, it's just that most of their business is in extract kits which require coarser milling of specialty malts. Most all grain brewers learn to ask for their grain to be double milled if the store doesn't already do that.