# cross hairs jump with heartbeat



## chip2 (Apr 8, 2015)

I have a Marlin .17 HMR with a bull barrel that I enjoy shooting. Lately, when shooting from a rest, I can see the cross hairs in the scope jump each time my heart beats. This makes it difficult to shoot consistent groups. Is this normal, or am I doing something wrong?


----------



## DJ Niner (Oct 3, 2006)

It sounds like you are supporting the rear of the stock with only your body/shoulder, which makes the front rest act like the pivot on a teeter-totter whenever you have any movement at the rear of the rifle (including your heartbeat moving your torso against the ground or bench). A rear rest (something like a "rabbit-ear bag" or an old sock filled with small round gravel or sand) can be used to support the rear of the stock, and can help minimize motions like the one you described. However, it also can be a source of problems if the stock is not still held snugly against the shoulder (once the small rear bag takes over the act of "holding" the rear of the rifle, sometime folks can get a bit sloppy with other aspects of their shooting position, because the rifle will still look steady on the bags even if it is "out" of the shoulder a bit -- but if this happens, it WILL have a negative effect on your groups).

The rabbit-ear or filled-sock bag is slid forward and back along the bottom, angled portion of the stock to make large elevation adjustments, and gently squeezed with the non-shooting hand to make precise, smaller elevation changes. Use of this type of bag may require adjusting your position, your front rest, and even the height of the bench, depending on how you had these items arranged in the past. Try it out and give it a chance to work, though, as it can be a _very_ steady way to shoot from a rest. When possible (sometimes the terrain interferes), I use a similar set-up when using a bipod in the prone position.


----------



## Steve M1911A1 (Feb 6, 2008)

...Or, you can just wait until you're my age. My heart stops occasionally, just so that it can scare the beJesus outta me. But I could use that moment to let off a shot.

My cardiologist tells me it's nothing to worry about: I'm gonna be dead soon anyway. Boy, will I be able to shoot accurately then!



(Sorry: The Devil made me write that.)


----------



## chip2 (Apr 8, 2015)

DJ, 

Thanks for the tip. That makes sense. I'll try it.

Steve,

I get it. I'm starting to feel my age too. Sometimes it's hard just to get out of bed in the morning!


----------



## TAPnRACK (Jan 30, 2013)

Try using a bipod so you can "load" it to avoid "barrel hop". Also use a rear squeeze bag under the butt of the stock. Avoid touching the rear stock of the rifle as you can send pulse signals through the stock... only touch the rear bag and grip section of stock. Being able to draw the rifle into the shoulder pocket while loading a bipod should keep you on target between shots and allow you to see your hits.


----------



## Philco (Apr 17, 2012)

Or.............do like us country boys do and learn to shoot between the heartbeats.


----------



## TAPnRACK (Jan 30, 2013)

You mean between breaths? Shooting during the natural respiratory pause? 

He may be experiencing breath control issues which is effecting his crosshairs staying on target.


----------



## DJ Niner (Oct 3, 2006)

Another note: if you are seeing a lot of movement when shooting from the bench, perhaps you have the scope magnification turned-up a bit higher than needed (assuming it is an adjustable-magnification scope). Just because the scope tops-out at 20x, doesn't mean you have to shoot groups with the scope _set_ to 20x; 10x to 12x may be all you really need.

Some of the best 100 to 400 yards groups I've ever shot were shot with various 6x and 12x fixed-power scopes. Try cranking your scope down a bit; any body/scope/rifle movement will be less visible, and therefore less likely to psychologically affect your shooting. As long as you have a clear aiming point, you should still be good to go.


----------



## chip2 (Apr 8, 2015)

DJ,

Tried your suggestion today. It seemed to help quite a bit. Thanks.


----------



## DJ Niner (Oct 3, 2006)

Glad to hear it!

Discussing the subject helped to remind me that I still need to replace my old rear support bag (gravel-filled sock). It started to leak gravel last fall, so I trashed it, but forgot (until now) to find/make a replacement. I'm thinking I'll use something a little more durable this time...


----------



## packrat (Jul 30, 2015)

Something like this one ? Dial back your scope a little and the sandbag behind the trigger as mentioned. With a low recoil gun like this you do not need to tuck into it that tight either. Great gun to practice with and for a new shooter. It functions just like a bigger bolt gun will without the cost. The down side for me is this thing is a tank to carry.


----------



## TAPnRACK (Jan 30, 2013)

DJ Niner said:


> Glad to hear it!
> 
> Discussing the subject helped to remind me that I still need to replace my old rear support bag (gravel-filled sock). It started to leak gravel last fall, so I trashed it, but forgot (until now) to find/make a replacement. I'm thinking I'll use something a little more durable this time...


Midway USA makes great bags on the cheap. $9-20 gets you a bag that lasts. Mines going on 3 years of monthly use and has survived 2 schools. Great bargain.


----------



## DJ Niner (Oct 3, 2006)

Even though I buy a lot of stuff from Midway, for some reason, I've never thought to look and see what they have available in this area.

Thanks for the recommendation!


----------

