The Box O’ Truth #51 – The Effects of a Rifle Rest on Groups

A recent shoot got me to thinking. (Dangerous, I know)

I have been told all my life that if a rifle barrel was allowed to rest on a hard surface it would have a bad effect on the accuracy. One school of thought was that a hard rest would result in larger groups. The other was that it would result in the group landing higher than normal on the target.

I have even heard hunters say that they had missed their deer because they forgot and rested their rifle on a hard surface, like a tree limb, and it had caused them to miss their deer.

I wonder if these stories are accurate? Only one way to know for sure.

I started out by resizing and preparing 50 rounds of .308 brass.

I then loaded them with a new, untried, and middle of the range load of 41.0 grains of IMR 3031 powder under a Sierra 168 grain BTHP bullet.

I did this so that we could shoot them through two different .308 rifles without giving either rifle an advantage of a custom developed load.

We are not looking for the “best” load available, but just want a load to compare a few different scenarios.

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I then built this rest out of some 2 X 4 lumber.

It is really simple, and will allow us to see how a rifle might change point of impact or group size when fired off a hard surface.

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We will shoot 4, five shot groups with two rifles. The first rifle is my Buddy Vern’s Remington, Model 7 bolt action, stainless, with a slim hunting barrel. It is lightweight for ease of carry when hunting

The second rifle is my Remington 700 VLS (Varmint Laminated Stock), with a heavy barrel. It is harder to lug around, but the thick barrel is nice and stiff and usually gives me good groups.

We will fire each rifle off of 4 different rests.

  1. A standard bench rest, with a sand bag.
  2. From the wooden rest, with the barrel resting on the rest
  3. From the wooden rest, with the fore end resting on the rest
  4. From the wooden rest, with a pad on the rest.

We will see what it does, if anything, to the groups and POI (Point of Impact). All groups will be fired at 100 yards, a common hunting range for around these parts.

By the way, it was very windy today and not the best conditions for small groups, but we are just looking for where the group lands, so that shouldn’t be too much of a problem.

First, the Model 7 off of the bags.

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Then the VLS off the bags.

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Here's the target.

Here’s the target.

The left group is from the Model 7 and is slightly high and left, while the right group from the VLS landed slightly low and right, but a nice group.

Now a little explanation about Point of Impact (POI) and Point of Aim (POA)

This load landed a little high and left out of Vern’s rifle. But that is because this is not his normal hunting load.

If he wanted to hunt with this load, it would be a simple matter of adjusting his scope until the POI and POA were the same.

But since he will not be hunting with this load, we will not worry about that for now.

We will just see if the POI changes with the different rests.

Then the Model 7 with the barrel on the wooden rest.

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Then the VLS with the barrel on the rest.

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Here’s the results.

Here’s the results.

The Model 7 shot an additional 2 inches higher to the left and the VLS group went a little over an inch higher.

An interesting note… Vern watched me shoot and said that the Model 7 barrel bounced about 2 inches high with each shot.

The VLS also bounced, but only about ½ inch.

Then the Model 7 with the fore end on the rest.

51-9Then the VLS with the fore end on the rest.

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And here's the target.

And here’s the target.

This brought the groups on both rifles almost to the original locations.

Who would have thunk it?

This cushion is made from some foam covering that is used on exposed water pipes in this part of the country to prevent freezing in cold weather.

It is split to fit on the pipes, so we just opened it up and wrapped it on the rest.

(We often used these on the windows of our deer blinds)

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Now the Model 7 on the rest with a cushion on the rest.

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And the VLS on the pad.

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And here are the groups, similar to those off the bench rest.

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Lessons Learned:
  1. Shooting with the barrel resting on a hard surface seemed to cause the POI to be several inches higher than with the fore ends on the rests.
  2. The slim “whippy” barrel was affected more than the heavy, stiff barrel by this problem.
  3. As long as the fore ends of the rifles were resting on the rest, the groups were pretty near to the same POI.
  4. If a hunter or sniper wants the POI to be the same, he had better be sure not to rest the barrel on the rest.
  5. It’s fun to shoot stuff.

(Thanks to Vern for the help)