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Gunsmithing Reading reamer print
- Thread starter krw
- Start date
Depending on who you ask, in this example it is one of the 2 circled numbers. I really do not know which one is correct since some say it is the top number and others say it is the bottom. I use the bottom number.
.169 is the freebore, as mentioned, but if one were taking measurements of a dummy cartridge, you’d have to consider all the space between the end of the case neck, to the beginning of the actual freebore, which is represented(mostly) in the upper number.
Edit: The distinction is a very minor one, but in some conversations, when people numbers aren’t agreeing much, it’s usually because one of them isn’t considering the total “effective” freebore.
Edit: The distinction is a very minor one, but in some conversations, when people numbers aren’t agreeing much, it’s usually because one of them isn’t considering the total “effective” freebore.
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It does have some, just not in the typical fashion. Never seen one like that before. The engineers at Nosler must have been enjoying themselves. I think it’s weird, and altered the dimensions in my reamer.
It doesn’t have any parallel freebore. True, your ogive may not be right at the case mouth, but this is zero frerbore.
I agree completely. Most people don’t care about that though, they just wanna know if the reamer will accommodate their target oal. In this case there’s .064” to accommodate some bearing surface.
I dont doubt it. I’ve seen some variations of this, just not quite like that. Certainly off the beaten path of modern cartridges, especially “match” cartridges.
Sure enough, the whole throat is the same. I ordered up a handful of prints from JGS and PTG on various 280 AI’s, and none use that throat.
This was my notation as a result of my conversation with Dave Kiff at Pacific tool.
Drawing supplied by the awesome folks at @CriterionBarrels
This is their .280 Ackley Match chamber
Dave said the "ogive touch point" was NOT specified on the drawing. He gave me the distance from the bolt face to the ogive touch point. He said it was between the points labeled "2.745" and "2.945" .
In this conversion I specified the 168 Berber VLD-Hunting bullet in .280 .
This was my understanding of our conversation and based on my other notes.
Drawing supplied by the awesome folks at @CriterionBarrels
This is their .280 Ackley Match chamber
Dave said the "ogive touch point" was NOT specified on the drawing. He gave me the distance from the bolt face to the ogive touch point. He said it was between the points labeled "2.745" and "2.945" .
In this conversion I specified the 168 Berber VLD-Hunting bullet in .280 .
This was my understanding of our conversation and based on my other notes.
Correct there is a curved surface (bullets nose) and an straight angular surface (lands ramping up), where those two interact depends on the exact relationship between the bullet and the ramping up lands.
In this image the area with the red squiggly I drew is was the distance between the end of the free bore and the actual touch.
^^^
What Hornady gauge would that be?
The OAL gauge measures what it's name states...not base to touching lands...?
What Hornady gauge would that be?
The OAL gauge measures what it's name states...not base to touching lands...?
Comparators.
https://www.hornady.com/reloading/p...s-and-gauges/lock-n-load-bullet-comparator#!/
Because its small stuff and you are big.
Its not complicated. Its just fine detail.
Brain fart....but I always looked at the bullet comparator as a way to get accurate relative measurements, not an actual measurement from base to lands. I guess, if the bushing is precisely the same as the bore diameter it would give that information. Never actually measured them as the relative measurement is what is typically looked at.
You are right, its a relative measurement. But thats all that matters, its for your tools and your equipment. Doesnt matter what the actual numbers are, you just want to see the difference from touch to where they are seated.
The OAL gauge pushes the bullet out of the case and to the lands, thats all it does. It doesnt measure anything, it just pushes.
You can then just the calipers to get the COAL/OAL (cartridge over all length) or you can use the comparators to get the CBTO (case base to ogive) measurement.
The OAL gauge pushes the bullet out of the case and to the lands, thats all it does. It doesnt measure anything, it just pushes.
You can then just the calipers to get the COAL/OAL (cartridge over all length) or you can use the comparators to get the CBTO (case base to ogive) measurement.
