Bullet ogive ?
- Thread starter 06shooter
- Start date
The *Bullet* comparator will tell/measure where that particular bullet/design
will contact the lands in a rifle.
You can then use that comparator measurement (which by definition references a specific
point on the bullet curvature) to set yourself a specific distance off the lands.
will contact the lands in a rifle.
You can then use that comparator measurement (which by definition references a specific
point on the bullet curvature) to set yourself a specific distance off the lands.
Head space is a firearm manufacturing tolerance only. Cartridges do not have headspace.
Bullet jump isn't measured. Every rifle has a slightly different chamber. Even two, identical, consecutively numbered, rifles have slightly different chambers. The distance from the lands will, therefore, be different. Really isn't something to worry about anyway.
Bullet jump isn't measured. Every rifle has a slightly different chamber. Even two, identical, consecutively numbered, rifles have slightly different chambers. The distance from the lands will, therefore, be different. Really isn't something to worry about anyway.
Chambers have a headspace dimension ...and spec.
Ditto, cartridge cases have a headspace dimension ...and spec.
(Check the SAAMI drawings sometime.)
While Hornady's Headspace Comparator is a few thou off, it's superb for
precisely & repeatedly setting up sizing dies to fit specific chambers.
Ditto the Hornady OAL Gauge. It is equally precise on setting up total cartridge
lengths for specifc bullet in specific rifles.
Ditto, cartridge cases have a headspace dimension ...and spec.
(Check the SAAMI drawings sometime.)
While Hornady's Headspace Comparator is a few thou off, it's superb for
precisely & repeatedly setting up sizing dies to fit specific chambers.
Ditto the Hornady OAL Gauge. It is equally precise on setting up total cartridge
lengths for specifc bullet in specific rifles.
NoSecondBest
New member
Cartridges do not have a headspace dimension....even per SAAMI. You're referring to the cartridge case length in a pistol caliber that headspaces on the case mouth. This isn't true headspace, it's the spec on the case length.
Here's a good article explaining what it's all about: http://www.gundigest.com/headspace-101-what-happens-inside-your-rifles-chamber
Please look at the two drawings and their specs in this SAAMI page:
SAAMI .30-06 drawing.
While a chamber may be the entity that has "headspace," per se (a noun)
BOTH chamber and case have headspace (an adjective) dimensions.
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Are you speaking about the Hornady (Stoney Point) OAL Guage Set, or their Headspace Comparator set ?
Each comes with 5-6 inserts with different diameter holes to match either
- Bullet caliber (224, 243, 257, 277, 284 and 308)
- Headspace case datum diameter (See http://www.hornady.com/store/Headspace-Gauge-Bushings/)
All inserts/bushing are marked.
(What are you try to measure ?)
Each comes with 5-6 inserts with different diameter holes to match either
- Bullet caliber (224, 243, 257, 277, 284 and 308)
- Headspace case datum diameter (See http://www.hornady.com/store/Headspace-Gauge-Bushings/)
All inserts/bushing are marked.
(What are you try to measure ?)
Bullet ogive & headspace are two different measurements. OAL to ogive will give you the amount of jump to the rifleing,Hornady Lock-N-Load Bullet Comparator. Headspace is the brass measurment. A fired round in your chamber will give you a perfect shape of your chamber,, when sizeing that brass you want to keep it as close to that fired size as possible. For bolt guns .001 - .002 with F/L sizing. Measures from bolt face (case head)to datum line on the case shoulder, Hornady Lock-N Load Headspace gauge. Hope I helped
Hey guys , I had a post recently about using Hornady head space body comparator, the diameter of it is .373 not .375 like what is stamped on the side of it.
I was thinking that the ogive comparator might be off too , that's why I'm asking about the most effective way to measure bullet jump.
The bullet comparator is .296"for .308" cal., if that's what it is supposed to be ,I guess I'm golden to rely on it.
I don't want to be going through the processes miss guided.
I want to be consistent with measuring ogive to rim , not tip to rim since that is inconsistent.
Thanks.....
I was thinking that the ogive comparator might be off too , that's why I'm asking about the most effective way to measure bullet jump.
The bullet comparator is .296"for .308" cal., if that's what it is supposed to be ,I guess I'm golden to rely on it.
I don't want to be going through the processes miss guided.
I want to be consistent with measuring ogive to rim , not tip to rim since that is inconsistent.
Thanks.....
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06Man listen, everybody's comparator gets a different reading. When you use the tool correctly and your caliper is a decently calibrated tool, you can accurately measure your BTO, Whats BTO thats base to ojive, base to ojive, I said it twice so you won't forget. When measuring BTO with a certain bullet, in a certain chamber, the measurement will be certain, ( Bart B. Says every 30rounds or so it will increase by .001.
Take the measurement with confidence! And use the measurement to acertain the the "jump" or "jam" your rifle bullet combination likes, and for god sakes pick up more literature about precision handloading, not that your asking too many questions, but some that are befuuzzlin you are totally academic.
Just study dude.
Take the measurement with confidence! And use the measurement to acertain the the "jump" or "jam" your rifle bullet combination likes, and for god sakes pick up more literature about precision handloading, not that your asking too many questions, but some that are befuuzzlin you are totally academic.
Just study dude.
NoSecondBest
New member
Dimensions don't equate to meaning headspace. Headspace is the dimensions of a rifles chamber. The dimensions of the cartridge are designed to fit into the rifle headspace. I can read the drawings and understand what the numbers are. However, headspace isn't a dimension on a cartridge. It's simple to find out what headspace is by definition. You can go to any number of knowledgeable places and get this meaning/definition. Cartridges are given critical dimensions so that they can fit into the spec/dim. of the rifles headspace. It's really not all that complicated. Don't try to interpret it differently.
From Wikpedia:
In firearms, headspace is the distance measured from the part of the chamber that stops forward motion of the cartridge (the datum reference) to the face of the bolt.
From Wikpedia:
In firearms, headspace is the distance measured from the part of the chamber that stops forward motion of the cartridge (the datum reference) to the face of the bolt.
Don't forget, folks, in ammo plants making bottleneck cases, a quality control guy measures finished cases with a gauge to measure their head to shoulder reference distance to ensure it met specs; SAAMI and military specs establish them. That's been dubbed "case headspace" for decades and SAAMI acknowledges it. So does 98% of everyone else making or reloading bottleneck cases as well as making tools and dies related to those processes.
1% that populace demand that headspace be the space between the breech/bolt face and case head when its full forward in the chamber. They either ignore, or are not familiar with SAAMI's glossary stating that's correctly called "head clearance."
The other 1% insist that headspace is only a dimension of the chamber from back end to some reference point on the chamber shoulder.
Have any of you "case headspace" naysayers ever considered championing your thoughts on the differences between "throat," "freebore" and "leade" as it relates to dimensions from chamber mouth to bore diameter?
1% that populace demand that headspace be the space between the breech/bolt face and case head when its full forward in the chamber. They either ignore, or are not familiar with SAAMI's glossary stating that's correctly called "head clearance."
The other 1% insist that headspace is only a dimension of the chamber from back end to some reference point on the chamber shoulder.
Have any of you "case headspace" naysayers ever considered championing your thoughts on the differences between "throat," "freebore" and "leade" as it relates to dimensions from chamber mouth to bore diameter?
NoSecondBest
New member
My point exactly. It's a reference dimension. It references the SAAMI spec interface for the rifles chamber. It may loosely be called "headspace" on the cartridge but it's simply referencing the rifle chamber interface dimension. The definition of headspace still stands as the true term for a rifles chamber. The cartridge must fit in to it. I've read thousands and thousands of drawings over almost forty-five years working as an engineer. I also taught a training class on reading blueprints. I'm not confused by this terminology. I've struggled with other engineers over the years on how to interpret drawings so it's not surprising that this is confusing to some shooters also.
IR12....
Which is why I simply tell folks that:
- Chamber headspace (dimension) is from the bolt face to the shoulder datum reference (diameer)
- Case headspace (dimension) is from case base to the same shoulder datum reference (diameter) -- and should be 1-2 thou less than the chamber dimension
Somehow that makes sense to them, ...and the bumblebee flies away happy.
