I have two bows. A 66" long, 42# @ 30" Blacktail Elite TD recurve that shoots a 32" long, 2018 aluminum arrow with 150 grain point weight. The brace height on the Blacktail is 7 3/4" and the nocking point is 9/16" above the shelf. The bowstring doesn't hit my arm so no arm guard is needed. I tuned my 68" long, 41# @ 30" Belcher Longhorn hybrid longbow today and I tried many different sized aluminum arrows (2016, 2018 and 2114), different brace heights, nocking point heights and point weights from 125 grains to 210 grains. This hybrid longbow likes a 7 1/2" brace height, with a 9/16" above the shelf nocking point and shoots a 32" long, 2114 aluminum arrow with a 210 grain point weight. The bowstring doesn't hit my arm, the arrow hits where I look, flies like a dart and no arm guard is needed. It can also handle a 175 grain point weight and the bowstring doesn't hit my arm either. With 2016 and 2018 arrows shooting 125 grains to 210 grains, the bowstring grazed my arm, but not too hard. Just experiment like I did and you'll find the arrow size, point weight, brace height and nocking point height which when it all comes together, the bowstring won't hit your arm.