Bullet diameter of 168 SMK

[gsg5pk]

My new ftr rifle was chamber with Palma95 + .150 freebore. (.342nk, .150fb, 1-30)

I load 168 smk + New Lapua Brass with coal 2.800 and can't chamber in this rifle. The bullet show mark on diameter. So, I ask my gunsmith and they reply with this


" One other possibility has come to mind- Is there a chance that perhaps the 168 Sierras you have are a little large on the diameter? The chambers and stub gauges will be .3085" in diameter in the throat. If your bullet perhaps is on the large side of the tolerance (.3087"?) the bullet would not even enter the throat as it should. I can't tell from the picture you sent, but this situation of a large bullet would leave a different mark on the bullet than normal. If the bullet is large, the throat in the stub gauge will leave a round ring on the bullet. If the bullet is not too large, you will see normal marks from just the rifling on the bullet. "


Do anyone have experienced with my problem? The coal to seat this lot of 168smk without any mark on bullet was 2.700"

 

[watercam]

Did you measure the cartridge base-to-land length before loading you cartridges? With shorter than SAAMI spec freebores it is possible to have a shorter than spec cartridge length. Use a Hornady OAL gauge or some other method to measure the distance from the bolt face to the bullet tip when touching the lands. I believe the Sierra 168s have an ogive that is longer than other match bullets (one of the reasons they have trouble making it to 1000 yards in the .308).

 

[XTR]

Is this a 600 yd ammo or 1000 yard ammo?

If it's a 1000 yard gun stop right now and get a different bullet. Short of a 300WM you will not get the 168SMK to 1000 yards super sonic, and they are prone to start tumbling somewhere round 900 (or less) depending on how hard you push them.

Have you tried to check your length to the ogive with a tool (like a Hornady tool)?

 

[BCoates]

I shoot 168 SMKs quite a bit, and my rifle has a Bisley Palma chamber with a 0.088" FB. My COAL when touching the lands is around 2.827" or about 2.245" OAL. If you have a 0.150" FB, then you should be able to load longer before touching the lands not shorter. I haven't measured the diameter of any SMKs lately, but it seams like they were 0.308" last time I checked. I don't have a micrometer, so I can get any more accurate than that.

 

[jpretle]

Is it possible your brass is too long???

 

[gsg5pk]

The mark on bullet was not grove mark. It look like the whole diameter of bullet ogive was bigger than .3085


The reamer that they use was custom reamer (case dimension was the same as Palma95 but the throat was 150")

 

[4xforfun]

.2838

 

[gaboon]

If I am not mistaken the palma chamber is designed for 155gr bullets.