by Tom Gaylord
Writing as B.B. Pelletier

This report covers:

  • The rifles
  • The test
  • El Gamo David
  • Discussion David
  • Diana model 35
  • Discussion Diana 35
  • Diana 27
  • Discussion Diana 27
  • Summary

Recently a reader posted a comment that he had improved his accuracy by seating pellets extremely deep into the barrel of his airgun. He said he pushed them in 40mm or more. So today I conducted a test to see what affect, if any, that has on a couple of my rifles.

The rifles

I selected the El Gamo David because we just saw it shoot. And I selected the Diana 35, which is a very accurate breakbarrel I last tested June of 2019. Then I researched both rifles and selected the best pellet from all my testing and also the best hold for each airgun.

The test

I shot off a rest at 10 meters. I shot 5-shot groups so I wouldn’t tire out in the middle of the test, but also so I could concentrate on my technique.

To seat the pellet deep I used an Allen wrench with 40 mm marked off on the shaft. I pushed the pellet into the bore until that mark was flush with the entrance to the breech. The reader who commented said there wasn’t any magic about 40 mm, it was just his way of telling us about how deep they were seated. And 40 mm works out to 1.5745-inches, in case you wonder.

40mm
The Allen wrench seated the pellets to about 40 mm deep.

El Gamo David

The El Gamo David shot best with RWS Meisterkugeln Rifle pellets. In Part four I put 5 of them into 0.166-inches between centers at 10 meters, resting the rifle directly on the sandbag. I shot the David first the way I did in Part 4 — seating each pellet with a ballpoint pen. The first shot hit the target to the right of the bull, but I continued to shoot the group anyway. Five pellets landed in a group that measures 0.607-inches between centers. It’s much larger than the group I shot in Part 4, so I will keep an eye on my shooting technique.

David Meister Rifle pen
When the pellet was seated with a ballpoint pen, the El Gamo David put 5 RWS Meisterkugeln Rifle pellets in 0.607-inches at 10 meters.

I was surprised that the group was as large as it was, given what the David did just last week, but maybe the group was more of an indication how well I was shooting — not the rifle.

Now it was time to seat the pellet deep. I started each pellet with the pen to get the skirt into the barrel, then pushed it in with the Allen wrench to the mark on the shaft. Then I shot each pellet just as carefully as before. This time five Meisterkugeln Rifle pellets went into as group that measures 0.648-inches between centers at 10 meters. It’s not much different and certainly no better than the first one.

David Meister Rifle 40mm
When the Meisterkugeln Rifle pellet was seated 40mm deep in the bore five of them went into 0.648-inches at 10 meters. This group is also a little more to the right than the last one.

Discussion David

So the El Gamo David didn’t do much different with the deep seating. Given the extra work that’s involved, I think this procedure is not for this air rifle.

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Diana model 35

Next to be tested was the .177-caliber Diana model 35. This rifle delivered remarkable accuracy when I last tested it in June of 2019. It likes Air Arms Falcons the best of all and back then it gave 10-meter 5-shot groups that ranged from 0.194-inches to 0.371-inches between centers.

I first tested it with the pellet seated flush and using the artillery hold with my off hand at the rear of the cocking slot. Five Falcons went into 0.25-inches at ten meters. Not only is that a great group, it also proves that old BB can still shoot. And, it is in the range of this rifle’s accuracy with the same pellet a year and a half ago.

David Falcon flush
The Diana 35 put 5 Falcon pellets in 0.25-inch group at 10 meters when seated flush.

Next I used the Allen wrench to deep-seat the Falcons 40 mm into the bore. This time, using the same artillery hold the Diana 35 put five Falcons into a 0.836-inch group at 10 meters. This time the difference between seating flush and extra deep is decisive!

Diana Falcon 40mm
When seated 40mm deep, the Diana 35 threw the Falcon pellets into this 0.836-inch group at 10 meters.

Discussion Diana 35

I was so glad to see that I was shooting okay. This is why it’s nice to have an air rifle that always delivers. Also — never sell an accurate airgun!

At this point in the test I had one result that was inconclusive and one that was decisively against seating 40mm deep. So I shot one more rifle.

Diana 27

This rifle is my Hy Score 807/Diana 27 in .22 caliber. I used obsolete Eley Wasp 5.6mm pellets for the test. First I shot five Wasps that were seated flush with the breech. They made a group that measured 0.555-inches between centers at 10 meters. They also struck the pellet trap noticeably louder!

Diana 27 Wasp flush
The Diana 27 put 5 Wasp pellets that were seated flush into a 0.555-inch group.

Now for 40mm deep-seated pellets. This time the Diana 27 put five Wasps in 1.207-inches at 10 meters — a definite degradation in accuracy!

Diana 27 Wasp 40mm
When seated 40mm deep the Diana 27 scattered five Wasps into 1.207-inches at 10 meters.

Discussion Diana 27

These three little tests are not conclusive, but they do indicate that seating a pellet 40mm deep in the barrel doesn’t help — at least not with these three rifles. It was such a bizarre idea that I just had to know for sure. If the reader who told us about this would like to write a guest blog and expand on what I have done here, he is certainly welcome.

Summary

When the idea of seating 40mm deep was first mentioned I didn’t like it because of the lack of cushioning the piston would get. However I did listen closely during this test and couldn’t detect any difference in the shot cycle.

At least we gave it a try!