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New 135 & 150gn Sierra Match Kings

#1
I have 100 each of these new bullets. Plugging them through the JBM ballistic calculator shows them to have almost identical ballistics, despite a 10% difference in weight and 6% difference in ballistic coefficient.

Presumably the 135 grainer is intended for .30BR, and should go well in my 7.62 x 39.

Does anyone have any idea why Sierra added these 2 bullets to their range, and why they have such similar ballistics?

Data:

308 dia. 135 gr. HPBT MatchKing .308 135 .203
.390 @ 3250 fps and above
.370 between 1900 and 3250 fps
.345 between 1500 and 1900 fps
.300 @ 1500 fps and below

.308 dia. 150 gr. HPBT MatchKing .308 150 .226
.417 @ 2800 fps and above
.397 between 2800 and 1800 fps
.355 @ 1800 fps and below

and for comparison, the old ones:

.308 dia. 155 gr. HPBT MatchKing .308 155 .233
.450 @ 2600 fps and above
.443 between 2600 and 1800 fps
.417 @ 1800 fps and below


.308 dia. 155 gr. HPBT Palma MatchKing .308 155 .233
.504 @ 2700 fps and above
.470 between 1800 and 2700 fps
.430 between 1500 and 1800 fps
.380 @ 1500 fps and below
 
#3
How much were they going for? I was quoted 43 pounds for 155 grainers!

I just ran the maths, and the normal 155 grain has a 10% better BC than the 150...
 

ugly

LE
Moderator
#6
His has a .308 barrel on it as have many US models, that said Sierra tested both sizes in both bores and no effect upon accuracy was noticed and no excessive pressure signes seen!
 

ugly

LE
Moderator
#8
It should be an absolute no no but what it does allow is a certain amount of flexibility when supplies are thin on the ground. RCBS dies come with 2 expander plugs allowing you to swop and resize the brass to suit the bullet!
 

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