What am I doing wrong?

[Llamma1]

I just started to shoot my longbow.I am new to traditional archery.I have shot a compound for the past several years and never slap my arm with the string but with my longbow it hits every time. What can I do to reduce the bruising?Any advice would be much aprisheated.    

[Killdeer]

Open your stance, rotate your elbow so that the lower edge is down and out, and see if your brace height is too low.

Hint: rotating the elbow can only happen when the arm is under tension, ie., grab a bow or wall and put pressure on your hand to try this out.)

Killdeer

[wapiti1997]

As your string stretches over time, brace height decreases increasing wrist slap.  I've found that I have to put a few twists in my string every 4-5 months.

[njloco]

If the brace height is correct, and If your also hitting left or right, hold the bow tighter, like your holding a suite case, or like you have an injured or baby bird in your hand. You don't want to hold it too tight and kill it but you don't want it getting away either.

[Jake Diebolt]

All of the above is good advice. I would also buy an armguard. I know a lot of compound shooters never use one, but I find I need one almost as badly as I need finger tabs.

There will be times, occasionally, when a bad stance or release makes the string hit your arm. You'll avoid some pain, and a bowstring hitting an armguard will affect your shot a lot less than a bowstring getting caught on bulky clothes.

[moebow]

Llamma1,  Also make sure your bow hand is not too deep into the grip.  If you're right handed, that would be twisted too far to the right.  Look at your thumb knuckle and see where it is.  I should be JUST to the right of the center line of the bow's center.  Many shooters end up with it way around to the right side of the bow.  That does many bad things like moving your bow arm into the path of the string, and putting your bow shoulder into a too weak of a position.  Do a search for a thread called "grip questions" , I posted a recommended grip position series of pictures there.