Actual chamber length vs SAAMI max OAL


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beatledog7
January 2, 2012, 03:57 PM
I'm loading for a bolt-action Savage Model 25 in .223, and I purchased a Hornady OAL gauge. It's easy to use, and with some practice I've been able to achieve pretty consistent measurements. I'm not using the associated bullet comparator, measuring to the bullet tip and averaging.

Here's the question and the concern: I get measurements for most bullets that are significantly shorter than SAAMI max OAL and in some instances shorter than the loading books specify for a given bullet.

For example, with a Hornady 55. gr #2266, I get a 2.200 +/- .003, which is right on the Hornady manual OAL. But the max OAL per SAAMI is 2.260.

Is it normal for rifle chambers to be shallower/shorter than SAAMI spec?

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rcmodel
January 2, 2012, 04:06 PM
No, in fact it's normal for them to be a lot longer anymore.

Some rifles use so much long leade or free-bore as to make it impossible to seat far enough out to reach the rifling.

See this thread just above yours about finding the max OAL for your chamber.
http://www.thehighroad.org/showthread.php?t=634639

Not to discourage you from doing it the way you are with your gage.
But try the candle smoked bullet deal I mentioned and compair the results.


rc

Walkalong
January 2, 2012, 04:25 PM
OAL is meaningless as far as chambers go. The base to the shoulder is what is important. Headspace.

The distance to the rifling can be important, and can limit the length a bullet can be loaded to. The tool you have allows you to measure the jump to the rifling. It does this measuring from the bullets ogive.

But, as rcmodel stated, usually there is more room there than you want. Some guns will not allow rounds to be loaded that can touch the lands. You simply cannot seat the bullets long enough to touch the lands and still be in the case. They have a long throat, or freebore, which helps pressures, but not necessarily accuracy. Target barrels will have short throats.

Double check how you are measuring things. SAAMI max is just that, a max. 99% of ammo is loaded shorter than the max. Seat the FMJ to the cannelure and you have the right OAL for that bullet, no matter what it measures, as long as it is under the SAMMI max. The bullet makers don't put cannelures in places on bullets where the bullet cannot be used, trust me on that one.

fguffey
January 7, 2012, 01:12 AM
"I am trying to measure my OAL from rim to ogive. I am using a Hornady OAL tool. First question, I am getting pretty inconsistent measurements .003-.015 differences in the measurements each time I try it using the same bullet, I am doing my best to do everything the same every time, what am I doing wrong? Second question just because I need to know. If I use a new sized case and start a bullet in the case and close it in the action, then take that dummy round out and measure it the same way with a comparator from rim to ogive, I am getting a difference in length by .020-.050" than I am using the Hornady tool, how can that be?"

But, as rcmodel stated, usually there is more room there than you want. Some guns will not allow rounds to be loaded that can touch the lands. You simply cannot seat the bullets long enough to touch the lands and still be in the case. They have a long throat, or free bore, which helps pressures, but not necessarily accuracy. Target barrels will have short throats.

There is no such thing as ‘by design’ the bullet not contacting the rifling , as in pushing the bullet out of the case before it contacts the rifling ‘EXCEPT’ for those that can not keep up with more than one thought at a time. It is a matter of not being able to have it both ways as in shooting short/light bullets and long/heavy bullets in the same chamber. I have checked wildcats in 7mm that would allow a 170 grain bullet to be pushed out of the case and travel an additional .170 + before hitting the rifling, The men that built the rifle made the reamer, etc.., nothing suspect about their ability, anyhow, one of the rifles just did not shoot, it made the usual rounds with bore scopes and hypotheticals, then I was asked why out of 5 rifles built only one did not behave in a manner that was predictable, and I said “I do not know, BUT!...etc..”

Beatledog7, I do not make dummy rounds, I make transfers and standards, advise you have been given between (posted) asking a question and the first answer was 9 minutes, I will try and take more time composing a response, because? You took the time to ask a question, I believe you deserve the extra time, and then there is the built in response, as in ‘WE’? answered your question, HERE! read this and you will know everything you need to know.
I have the luxury of disagreeing, as in being granted the luxury or because there is no other option.

Yes, you can use cases with tight necks, cases with tight necks have bullet hold, again, I make transfers and standards, transfers must have bullet hold, if you follow the instructions given and shred the neck to lesson
bullet hold you turn the case into a ‘squid neck case’, the squid neck case is not a good transfer, sheading the neck of the case is busy work, so, I suggest drilling the primer pocket/flash hole out to a diameter that will/would accommodate a cleaning rod, then seat a bullet in the ‘test case’ (seat the bullet short, I do not care how short because you do not want to seat the bullet when the test case is chambered or contact the rifling before the shoulder of the case contacts the shoulder of the chamber) then remove the bolt, chamber the test case, after chambering the case insert the cleaning into the drilled out flash hole/primer pocket and push the bullet out of the case until it contacts the rifling, then stop, remove the cleaning rod, remove the test case, upon removal the test case become a transfer, because??? how???? Why???? Again, I want to transfer the chamber dimensions to my seater die as in your question “from the rim to the ogive/bullet contact”.
The case that started out as a test case then became a transfer measures off the lands as in .000 for MY!!!! chamber, not SAMMIES, not my neighbors, I am not loading for SAMMIE, I am not loading for my neighbor, and that is the reason I want to transfer my dimensions from my chamber to my seater die, by, backing the seater stem/plug off the die and backing the locking nut off then adjusting the die down to the die contacts the mouth of the case, then back the die off to prevent crimping, then secure the locking nut, then screw the seater plug/stem down until it contacts the bullet, THEN secure the seater stem to the die. This technique allows me to adjust ‘off the lands from .000, again all of my seating dies are adjustable in .000 thousands with a dial caliper, depth micrometer, dial indicator with a set up fixture etc., etc., and that is without Hornady/Sinclair, Larry Willis.

F. Guffey

fguffey
January 7, 2012, 01:28 AM
pinching the case neck for bullet hold? I am the fan of bullet hold, I do not make squid neck cases, pinching the neck will cause the bullet to be seated off center, who knows by how much but when chambering the round the chamber will cant the case and, or the neck or the bullet, now that should account for some of the wild measurements, anyhow, I make transfers, I am a big fan of transfers and standards, and I prefer bullet hold over loose necks, again, as I said, why go to the bother if all the effort is not about making a transfer to transfer the measurements without purchasing all of those nice tools, nice tools are nice to have, they are not necessary, they are just nice to have, then after a reloader learns how to transfer a measurement from the chamber to the seater die they can purchase nice tools.

Winchester and I had words, I wanted a chamber to fit my dies OR! I wanted dies to fit their chamber.

F. Guffey

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