problems with new Sierra 155 Palma

[1000yardstare]

Finally got my hands on a box of the new Sierra 155 gr .308 Palma bullet, #2156.

Have been testing them with different powders and seating depths in my Savage VLP. GOD AWFUL! Random distribution on a 300 metre target. Couldn`t even call it a shotgun pattern.

I know the rifle can shoot. Today put five Lapua 155 gr Scenars loaded over Varget into 1 5/8 inch (0.50 moa) at 300 metres.

Diameter is the same for the Lapua and Sierra across the pressure ring at the base of the bullets. Decided to compare bearing surfaces. The Scenar bearing surface is a good 1/10 inch longer than the Sierra. So at least in my rifle it appears there just isn`t enough bearing surface on the new Sierras.

Has anyone else experienced the same problem?

Shown below is a pix of the 155 gr Scenar target shot today at 300 metres on the ICFRA 5 ring target, 1/2 minute centre V-ring. Scores 25-3V.

 

[rcw3]

That kind of posting can launch a real firestorm with some in the shooting community, especially when Sierra is a sponsor to some of the shooters. The Sierra bullet does have a very short bearing surface, some still swear by it, and some swear at it. Lately, I have taken a liking to Berger's 155.5 gr bullet in that bullet weight range. The Berger has a bit longer bearing surface than the Sierra, as do most of the other 155 - 155.5 gr. Palma or Fullbore bullets.

Robert Whitley

 

[Mark S in NM]

I'm with Robert on a few points. I swear at them '2156's'. Having great success with the Berger 155.5 full bores.

 

[JERRYHM]

Use the correct chamber and the Sierra 2156 and the Berger 155.5 will shoot.

Five shots at 300 yards.

 

[memilanuk]

I have a bunch of the 2156s but I haven't gotten around to making a serious run at getting them to shoot. For the B155.5BTs they really like to jump - 40-50 thou or so. If your throat is chambered for a bullet with a longer bearing surface, you might try backing the Sierras off a ways and see if something interesting appears...

 

[Martin52]

In my experience, the 2156 generally appears to shoot well provided it has between 30 and 50 thou jump, it does not group as well if closer to, or in, the lands. I recently changed over to the 2156 and like it a lot, especially at 600 yds +.


Martin

 

[1000yardstare]

JERRYHM...........very impressive target. I notice it is with Bergers. The Canadian Palma Team has switched to Bergers.

Have tried various seating depths with the new Sierra 155 including a long jump with no success.

I am wondering if the short bearing surface of the new Sierra requires a no-tolerance bore as found in custom barrels. My Savage VLP is a stock factory rifle. Given manufacturing tolerances maybe my VLP has a slightly loose bore.

Reminds me of the bad old days in Canadian Palma when we had to shoot the .308 ammo the Army gave to us. OK with Dominion Arsenal ammo made in the 1950s and 60s but when the Army switched to a civilian contractor, IVI, problems arose. The IVI bullets are undersized to slow down fouling in machine guns. DCRA shooters had to buy custom undersized bores to shoot the stuff. Thankfully we can use reloads now. If you see a barrel maker advertising IVI barrels that is the story.

Any other Sierra SMK bullet I have used, 69, 80, 107, 142 have been very accurate. Just disappointed that the new 155 is not working for me.