Two things.

First - You must have one heck of a good ticker on you.

Second - Sounds to me like maybe your holding onto and pushing your gun a little to hard into your shoulder, try and relax your grip some. Easer said than done if your used to shooting that way for many years. Just a thought sonny.

Yes Walleyes the last time I went for a stress test the Doc said I had an excellent ticker.

He wasn't sure about the rest of me tho.

I do like to hold the butt up tight to the shoulder and I might have to slack off some on my grip.I never had a problem like this with my old Winchester model 70 in .30-06 but then 6 power is the most I used on that rifle.Could a wood stock maybe absorb heartbeats better than a synthetic stock?

I did get a 1.25 inch group with this rig on 6 power but my goal is to hit the 500 yard gong and I like to crank up the power a bit.

A while back I tried coachman's lead sled and I wasn't really keen on having the lead sled back stop between my shoulder and the rifle butt but I may have to revisit this.

Anyways thanks for the helpful tips.

Well sonny my wife says I have no heart or feelings, so no problem there. Back about a hundred years ago, I was in the cadets for a short time and we had a real solider come in and show us how to shoot. He would always tell us that shooters hold their breath when they are trying to pinpoint the target, and when they do that their heart rate will go up.  Don't know, but the biggest thing I think is the relaxing part, as other have said. It's a mind game just before the shot is taken, so relaxing through it is key. Also I have had this happen to me if I had coffee before I shoot, makes my heart thump like a rabbit. I think you'll hammer the gong, just need to get in your comfort zone and burn powder to achieve it. I don't like using a locked in type rest, just a front bag and my arm tucked under the stock at the arm pit.   

     I think guns are turning you on just a touch to much.  Try thinking about something else when your shooting like taxes or Justin Trudeau or something hehe.

    In all seriousness I'd echo not using the fixed rest.  I abandoned them a few years ago and haven't looked back.  Something soft like a backpack or couple jackets in the front and arm cradling the stock will do the trick if sandbags aren't handy.  Actually really prefer the backpack because it's always handy in hunting situations and works really well height wise.  To add to that often you'll see the real long range guys using a mat and laying down with only a front rest.  Imho it's the steadiest way to shoot.  I'm not a long range guy but Ive shot my best groups that way anyways. 


   

I like my lead sled, have had it for two years now, sure saves on shells checking rifles pre season.

You can use it any time, I  think I will go back to sand bags if I ever get healthy again.

Thanks but I bought myself a Christmas present. 

Speaking of bags I looked at these and they look pretty good.

The weight of the rifle makes the bag grab hold of it..

https://www.cabelas.ca/product/29128/caldwell-tack-driver-shooting-rest