Can someone double check my measurements? 6.5 Creedmoor: OAL and Chamber length.

[jetracer013]

I'm new to hand loading for rifle and have been doing a lot of reading on here which , has been extremely helpful but, I still have a few questions. I read the sticky regarding "start OAL" which indicates that I should be jamming the rounds for my OCW tests. I purchased a Hornady OAL guage and believe I have gotten correct measurements but, they seem to be too long.

I have two rifles so I measured both, and what I found is that I would need to be longer than mag length, to get either of them to jam the lands. (using berger 140 hybrids)

Proof Savage pre-fit: OAL: 2.938 Base to Ogive: 2.1935
Rock Creek barrel: OAL: 2.9195 Base to Ogive: 2.178

Does this seem correct?

The other thing I read on here was the "reloading 101" sticky which recommended measuring the chamber and trimming cases "just short of that measurement". Again, I bought the tool, prepped the case and measured. And again, these both seem to be pretty long to me.

Proof Barrel: 1.9445
Rock Creek: 1.942

None of my fired cases were anywhere near this length. Should I just keep firing them until they get closer to the chamber length and then trim? And how close to the chamber length is acceptable?

Thanks in advance for any help you can provide.

 

[spife7980]

I dont have any particular numbers for myself to offer but: You should only be jamming if you are trying to find your absolute maximum load which isnt a bad idea for a new rifle/reloader, pressures are highest when the bullet is jammed so if you find that maximum point you can proceed below that point with confidence that you wont blow yourself up. If you are constricted to mag length restrictions I would start at the maximum magazine length for the ocw part and then work shorter from there for seating depth tests.

People like to find the distance to the lands (or just barely touching) and not the jam length as jam length can vary just like length off the lands can vary, only in an inverse measurement. If the lands are our zero point (.000) you can jam into (+.001-.025) and those will be more useless than knowing where the beginning of being off the lands (-.001-however far back necessary) if youre trying to find your distance from the lands erosion or for how far your bullet jump is.

I follow the Wheeler Accuracy method as displayed in this video to find mine.















What platform are you reloading for? You mention that you tested two different barrels so Im going to guess that its a savage style with the barrel nut set up? If so you can set up the cartridge to give as much or as little head space as you want and you can change it with each install so be weary of trying to take a measurement, removing it and then trying to use the first times numbers with a subsequent install if you dont space it exactly the same with a reference mark. If those are shouldered barrels then you can only twist them on and off to one particular spot each time so ignore the previous part of this paragraph. In any case make sure that they will close on a gogauge and not on a nogogauge.



You then mention the trim lengths and that you have a tool to measure that? Wouldnt that tool just be a plain jane set of calipers to measure the overall cartridge length? I see on the saami website (page 39 http://saami.org/specifications_and_...FR.pdf#page=13 ) that the max length of a saami 6.5 creed cartridge is "1.920-.02" That means 1.920 is the longest with -.02 back as still in spec. So anywhere from 1.900 to 1.920 would be acceptable trim lengths, I try to shoot for the middle of that gap and would trim mine to 1.910. That way it will never be too long but I also wont be too short either. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/thefirearmsforum.s3.amazonaws.com\/2011\/01\/120753_ba2f11e2e93967605be1ff499ab6bc83.jpg"}[/IMG2]







Edit: They hybrids are a hybrid of the secant and tangent ogive forms. Secants have a sharper corner where the nose curves to meat the bearing surface than engages the rifling. Tangents are more rounded. What this means is that you can get the better BC that comes with a secant nose profile that is generally seating depth sensitive but make it less sensitive by going hybrid with a tangential pattern that is less depth sensitive. So I would imagine that jamming your bullets wont be necessary. If they were straight secant then yeah maybe but the hybrid is developed so that you wont have to jam them. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/www.accurateshooter.com\/wp-content\/themes\/paul\/uploads\/\/pid5567_tangentsecant01big.png"}[/IMG2]

 

[_Raining]

You then mention the trim lengths and that you have a tool to measure that? Wouldnt that tool just be a plain jane set of calipers to measure the overall cartridge length?

I think he means he measured the chamber to see how long his case length is before it maxes out in the chamber. Also if you bought a blank and had a gunsmith install it, they should have asked you what bullet you were going to use and ream it based on that so you can be close to the lands with mag length.

 

[winniedonkey]

I dont have any particular numbers for myself to offer but: You should only be jamming if you are trying to find your absolute maximum load which isnt a bad idea for a new rifle/reloader, pressures are highest when the bullet is jammed so if you find that maximum point you can proceed below that point with confidence that you wont blow yourself up. If you are constricted to mag length restrictions I would start at the maximum magazine length for the ocw part and then work shorter from there for seating depth tests.

People like to find the distance to the lands (or just barely touching) and not the jam length as jam length can vary just like length off the lands can vary, only in an inverse measurement. If the lands are our zero point (.000) you can jam into (+.001-.025) and those will be more useless than knowing where the beginning of being off the lands (-.001-however far back necessary) if youre trying to find your distance from the lands erosion or for how far your bullet jump is.

I follow the Wheeler Accuracy method as displayed in this video to find mine.















What platform are you reloading for? You mention that you tested two different barrels so Im going to guess that its a savage style with the barrel nut set up? If so you can set up the cartridge to give as much or as little head space as you want and you can change it with each install so be weary of trying to take a measurement, removing it and then trying to use the first times numbers with a subsequent install if you dont space it exactly the same with a reference mark. If those are shouldered barrels then you can only twist them on and off to one particular spot each time so ignore the previous part of this paragraph. In any case make sure that they will close on a gogauge and not on a nogogauge.



You then mention the trim lengths and that you have a tool to measure that? Wouldnt that tool just be a plain jane set of calipers to measure the overall cartridge length? I see on the saami website (page 39 http://saami.org/specifications_and_...FR.pdf#page=13 ) that the max length of a saami 6.5 creed cartridge is "1.920-.02" That means 1.920 is the longest with -.02 back as still in spec. So anywhere from 1.900 to 1.920 would be acceptable trim lengths, I try to shoot for the middle of that gap and would trim mine to 1.910. That way it will never be too long but I also wont be too short either. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/thefirearmsforum.s3.amazonaws.com\/2011\/01\/120753_ba2f11e2e93967605be1ff499ab6bc83.jpg"}[/IMG2]







Edit: They hybrids are a hybrid of the secant and tangent ogive forms. Secants have a sharper corner where the nose curves to meat the bearing surface than engages the rifling. Tangents are more rounded. What this means is that you can get the better BC that comes with a secant nose profile that is generally seating depth sensitive but make it less sensitive by going hybrid with a tangential pattern that is less depth sensitive. So I would imagine that jamming your bullets wont be necessary. If they were straight secant then yeah maybe but the hybrid is developed so that you wont have to jam them. [IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/www.accurateshooter.com\/wp-content\/themes\/paul\/uploads\/\/pid5567_tangentsecant01big.png"}[/IMG2]

Thanks for that video post. Learned and will try it out. Thanks

Sent from my HTC6535LVW using Tapatalk

 

[jetracer013]

Thanks Spife. You are correct, I am trying to establish my max charge weight. I have a berger manual, and have read Hodgdons reloading data which both suggest a max charge of around 40grains. However when I look at what everyone posts for recipes, I see charges in the 42-44grain range. I have read the reloading stickys carefully and it seems to suggest that I can gradually approach that charge as long as I keep an eye out for pressure signs and quit before I reach the point of case failure. I do not intend to jam the bullets after I establish my max charge weight. (unless I find a reason to do so later on)

Thanks for the video. I will give this a try and compare my measurements. I also like the idea of using and actual cartridge, rather that then hornady modified case, required by their tool.
For reference, this is the tool I am using:
http://www.sinclairintl.com/reloadi...ating-depth-tools/length-gauge-prod70272.aspx


Regarding the Chamber length, I am using the sinclair gauge found here: http://www.sinclairintl.com/reloadi...s/sinclair-chamber-length-gage-prod32925.aspx

Again, my reason for doing so is, I read the reloading sticky and it recommended leaving the cases longer than the trim spec in order to give more support to the bullet. Maybe this is something I should play with later and simply trim to spec for now?


I should have been more specific regarding my rifles earlier. I am using a rock creek barrel on a savage model 10 action and a proof barrel on a bighorn TL3. Both are fully assembled by myself, using forster headspace gauges. Neither barrel was specifically reamed for any particular bullet.

Thanks again for the help.

 

[jetracer013]

I guess my real question was, does it seem like my proof is eroded? I never measured (or had the means to) when I first got it. I have approx 1100 rounds through it now with about the same on the rock creek.

 

[spife7980]

In reference to the OAL/ogive measurements: possibly its eroded or perhaps you just have them jammed .02 deep into the lands and not at the start of the lands or it could just have a throat thats cut longer to account for the longer/heavier for class bullets (which also bring to point that bullet profiles differ and as such where the ogive comparator gauge interacts with the bullet changes depending on the particular bullet) . Without having a chamber print or reamer design specs or something comparing the two its really just a wild ass guess from this side of the internet.

I wouldnt imagine that the neck would really be .02 longer than spec. I suspect that maybe the necks could be a tiny bit tight and could possibly be dragging on that sinclair gauge pulling it back out a bit? Or it really is that long. Again it depends on something I cant see right here in front of me. I personally would stick with the spec rather than letting the brass grow an extra .02 if your measurement is correct.

Measure the fired brass on the shoulder with your comparator and subtract .002 from that measurement to find what the sized shoulder length should be. Once you have the brass cases bumped back I would then proceed to finding the lands with the wheeler method in the video I linked. See how your results from that method compare to your results with the hornady length tool to see if you did it correctly. If they disagree then you will know that one fo the two is wrong.