Bearing Surface Comparitor

[bully_eye]

Received my BSC from SSS in the States today- one week from order to delivery. Looks well made and very solid. I'll let you know some results after I get a chance to run some projectiles through it.

Michael

[VickiMcc]

Whats the BSC for ???

[bully_eye]

Measures a projectile from he base to the ogive. Theory goes that you can't really sort bullets by weight- for example I think Sierra claim a .2gr tolerance on the MK's. What people have found though is that projectiles will vary in length by anywhere up to .007" from base to ogive. Imagine if you were seating .005" into the lands... if there is .007" difference between longest to shortest then some projectiles may not even be touching with the obvious results for pressure and down range elevation. I'm not saying this will improve my scores one bit but every step you take to produce the most consistent loads means most errors will be the drivers. I just figure if I go to the trouble of weighing cases, beburring flash holes, neck turning etc then why not go one extra step. Next step will be to buy a meplat uniformer! If you want a better explanation of the BSC go to www.davidtubb.com

Michael

[AlanF]

Michael,

I agree that bearing surface variation is worth trying to keep to a minimum, but more as way of getting consistent BC than distance to the lands. Because bullet seaters work on some part of the ogive, not the base of the bullet. So for distance to the lands, the consistent dimension needs to between two points on the ogive, one which first touches the lands, and the other which the seater touches.

I have a meplat trimmer from Jeff Rogers (a.JR on this forum). Haven't used it enough to make a judgement on how much it helps (probably of more benefit at the v. long ranges), but at the price, its well worth a try.

Alan

[bully_eye]

You're probably right about that Alan. I think in the end though, like I said, it is just about enhancing unifomity, and like a meplat trimmer, allows us to split hairs to the nth degree- besides that, it looks cool and it gives me something to convince other people they need to have to be competitve! hehehehe

Michael

[a.JR]

ED

[bully_eye]

Hi JR,I understand the theory behind meplat trimming and take your point about other measurements on the projectile being important, but when you say you get 0.00125" uniformity from case head to meplat for your match rounds, isn't case head to frontal bearing surface going to be a better measure of the consistency of your loaded rounds as this is the point where your projectile is going to engage the lands?

Michael

ps I lied in my description of the product. It doesn't measure base to ogive as I said but rather the bearing surface itself- kind of in the name. BIG difference.

[AlanF]

Jeff,

With SMKs, if you get for example a long base to ogive, does this normally correspond to a long boat-tail, or a long bearing surface, or a bit of both?

Alan

[a.JR]

Ed

[a.JR]

ED

[Tony Z]

edited 15/11/05

[bully_eye]

.... and then of course there are the people who may be described as the laziest hand loaders on earth who do none of these checks and still win- ANYTHING you can do to iron out inconsistencies is a positive.... even if it is only putting your mind at ease.

Michael

[Tony Q]

You said it!

Going into bat with the ‘Best Ammo’ and the ‘Best tuned gun’ will give you a very important psychological boost. It all starts in the mind.

Those who can shoot top scores with a box of std hand loads and armed with a lump of wood bolted to a good barrel have 1 thing in common … a clear mind.

The second you start thinking of your equipment or ammo not being as good as it should is the time you start messing things up.

Clear Mind and a Positive mental attitude goes a very long way.

Now, if I could just master that and find that real world OFF switch in my head!!! …

[Tony Z]

edited 15/11/05

[bruce moulds]

hi,
apparrently mid tompkins just weighs his projectiles.
bruce moulds.