2 Grains in bullet weight? Really?


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mnhntr
April 30, 2012, 11:29 PM
I have started working loads for my .260 LRP and things are coming together. I am using 140gr VLDs and 142gr SMKs, topping H4350. I am having a hard time grasping why the loads are so different for 2 grains in bullet weight. The bullet design is so similar. I really want to use the VLDs but the SMKs are able to be pushed so much faster.
Hodgdon says 39 to 42gr of H4350 for 140gr bullets
For the 142gr SMKs its 41.5 to 44.5gr
I am sure RC will have the answer to this, anyone want to weigh in and give me some insight as to how they come up with this?

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blarby
May 1, 2012, 12:18 AM
Prolly has to do with some combination of bearing surface, and BC.

Don't load for .260, but that'd be my answer regardless.

ArchAngelCD
May 1, 2012, 02:30 AM
I have started working loads for my .260 LRP and things are coming together. I am using 140gr VLDs and 142gr SMKs, topping H4350. I am having a hard time grasping why the loads are so different for 2 grains in bullet weight. The bullet design is so similar. I really want to use the VLDs but the SMKs are able to be pushed so much faster.
Hodgdon says 39 to 42gr of H4350 for 140gr bullets
For the 142gr SMKs its 41.5 to 44.5gr
I am sure RC will have the answer to this, anyone want to weigh in and give me some insight as to how they come up with this?
First, according to Hodgdon the velocity difference is only 58 fps, not all that much IMO. Secondly, the bullets are not "so similar" at all. Sure the weights are almost identical but a Nosler Partition (BC .490)and a Sierra MatchKing BTHP bullet (BC .580)are not nearly the same. The Nosler bullet is a strong hunting bullet designed for deep penetration while the Sierra bullet is designed for target accuracy, velocity and long distances. Actually, a difference of only 58 fps speaks well for the Nosler Partition bullet up against a target bullet.

BTW, why would you use a MatchKing bullet for hunting over a hunting bullet. If you really want to use a Sierra bullet you should be using the 140gr GameKing. (BC .490, the same as the Nosler bullet)

kingmt
May 1, 2012, 07:24 AM
On top of what was already said. The data is what they used not what can be used.

Striker Fired
May 1, 2012, 07:54 AM
As Kingmt as said,that was just the data they used to test.You can use the same charges for both bullets as long as the seating depth is the same.

USSR
May 1, 2012, 10:30 AM
As has already been stated, the load data in reloading manuals is simply what they used, and is not written is stone (although it is a good idea to follow published data). Where they stop, as in what some manuals call a "Max Load", is subject to some debate, as some reloading manuals are quite conservative with this. I once called Sierra regarding a Max Load and talked to one of their technicians. He told me that they didn't have the pressure specs for their Max Loads, that whatever the charge weight was for a Max Load, was merely where they decided to stop. So much for science.

Don

mnhntr
May 1, 2012, 12:56 PM
First, according to Hodgdon the velocity difference is only 58 fps, not all that much IMO. Secondly, the bullets are not "so similar" at all. Sure the weights are almost identical but a Nosler Partition (BC .490)and a Sierra MatchKing BTHP bullet (BC .580)are not nearly the same. The Nosler bullet is a strong hunting bullet designed for deep penetration while the Sierra bullet is designed for target accuracy, velocity and long distances. Actually, a difference of only 58 fps speaks well for the Nosler Partition bullet up against a target bullet.

BTW, why would you use a MatchKing bullet for hunting over a hunting bullet. If you really want to use a Sierra bullet you should be using the 140gr GameKing. (BC .490, the same as the Nosler bullet

I am not using this for hunting not sure how you got that from my post. The 140gr bullets I am talking about are VLDs not Nosler. Not sure how you got that either. The two bullets I mentioned are very similar.

mnhntr
May 1, 2012, 01:00 PM
As a side note the data I got from Berger states 37gr-41.7gr for the 140gr VLD

kingmt
May 1, 2012, 01:35 PM
I must have picked up on the Nosler also. A all brass bullet will be longer then a jacketed lead bullet. More surface area gives more pressure.

I assume they are all brass.

LoonWulf
May 2, 2012, 03:07 AM
I believe most of the data Berger puts out is strait from Quickloads, and is a good starting point.

I have used VLDs in a couple cals but i dont own a 6.5. I have found that I can generally work over bergers suggested maximums, but i do so VERY carefully.

In one instance (my 6x47), I have a load for the berger 6mm 95grn VLD that was the same as a 70grn balistic tip. When i posed this as a question to Walt Berger he suggested it was likely do to the relatively short bearing surface of the VLD design. As a note, there IS no (or atleast wasnt when i asked about it) data for the 6x47 with berger bullets.

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