Swiss Arms PE-90 “Over The Beach Test” Final Results and Conclusions

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Swiss Arms PE-90 “Over The Beach Test” Final Results and Conclusions

A few months ago, I came to the conclusion I wanted to switch my well used (8000+ rounds fired) PE-90 barrel from a 1in7″ twist to a 1in10. Since I knew the 1in7 had near 8,000 rounds through it, and I would be getting a brand new 1in10, I decided the 1in7 was expendable. This gave me a “spare” barrel to attempt a destructive test I had yet to see performed with a SAN rifle, and have desired to try for several years; an Over The Beach test.

I went out to the San Juan River, and after briefing 2 partners on the safety procedure, prepared for the test.

Test procedure:

-Submerge loaded and chambered rifle, and allow bubbles to stop rising

-Remove rifle from water and fire, allowing no more than 2 seconds for the rifle to drain

Once I had made my way hip deep into the (Mid April cold) river. I submerged the rifle and waited for all the bubbles to stop coming out. This actually took about 15 seconds and a bit of shaking. I then pulled the rifle out of the water and fired of a 5 round magazine a fare distance from my face, the rifle functioned reliably.This gave me some confidence, and I started raising, and taking aim with the rifle, bringing it closer to my face and head. I continued until I was freezing cold, and shriveled 😉 (15 more rounds) All rounds fired reliably.

I then fired 20 rounds on a 12″x12″ pizza box at about 50m to check accuracy and noticed it was not the same. Out of 5 rounds offhand I only hit the pizza box 3 times. Then I moved to 25m and from a make shift rest hit the box about 13 out of the remaining 15 rounds. This was shooting some Norinco 55gr ammo that had key holed out of my barrel in the past due to inconsistent bullet diameter, and after the test they were key holing even more consistently than before. When I got home, I tried 10 rounds of AE 55gr, and scored a grapefruit sized group off hand at 50m. So it shot the AE 55gr much better, but the bore was obviously still damaged, and accuracy gone.

I sent the rifle off to the gunsmith to have the new barrel put on, and to examine the old one. He concluded that the barrel was damaged by the OVB test and nearly shot out (This surprised me a bit). At the muzzle end there was apparently very little rifling left, he suggested excessive low quality ammo being fired may be the cause of this. We also discussed at length the dangers of performing such a test. There’s a great chance of causing whats sometimes referred to as ring bulge in your barrel. When asked about performing such a test with an HK416, an H&K technician described it like this: One of the SEAL’s demands was that the rifle be able to function reliably without adequate drainage time, this bulging of the barrel is viable for them in an emergency scenario. What happens when a bullet travels down the barrel is the water in front of the bullet can’t compress like air does, and so some of that water wants to pass over the bullet. Since the water can’t compress, the pressure build up, bulges the barrel. This is why it is considered a destructive test 😉 To pass the test, the rifle simply needs to keep working, accuracy will probably be gone along with full velocity, and continued use of the barrel. But if it functions, it passes the test. Regardless of what platform it’s done with, this is an extremely dangerous and destructive test and what they don’t show you in the HK416 OVB video, is that you will likely need to replace the barrel due to these issues. I was contacted by another guy who tested some SG551’s with 14″ barrels for the RCMP and during an OVB test just like mine, they blew one of them up at the barrel. Knowing full well the destructive capabilities of this test, I would not have performed it had I not had a “spare” barrel to try it on.

I have included a photo of the visible cracks on the outside of the barrel, that clearly show where the bulge occurred. The picture of the cracks in the barrel, combined with someone in the know informing me they blew up a 551 doing this test, should be more than enough to show the true destructive nature of this test, and convince anyone who may be thinking of trying this with there rifle, that it’s not a good idea.

Result: PE-90 gets passed the OVB test reliably

wpid-testUpload.pngConclusions: Damaged Barrel. Ring Bulge. Lost Velocity and Accuracy. Do not try this with a barrel or gun your not willing to replace or blow up.

– Steve

Red arrows point to bulge cracks below

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