Hornady OAL gauge and bullet comparator

rayzorloo

rayzorloo

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Hi folks,

I'm looking for some input here, I bought the Hornady OAL gauge and bullet comparator with inserts. I am loading 6.5 creedmoor for a 783. I go ahead and use the gauge and insert as instructed. I measure for the bullet (Sierra match king 142gr HPBT) I am using and get measurement of 2.27 CBTO, I've read and watched that I should back that up 0.02. Did that and tried to chamber the dummy round but I could not lock the bolt. Backed it up another 0.02, that locked the bolt but it needed some force. Then when I tried to pull the bolt back it also required a tiny bit of force to open. Should I back it up some more? I know every gun is different in how much to jump the lands, but should I back it up some more? If I back it up another 0.02 that would bring the CBTO to 2.21 or 2.79 COAL. Is this safe to do?

Thanks in advance
 
Talltimber1 said:
You need a headspace gauge not the bullet comparator
Click to expand...

No. That have nothing to do with headspace.

Good advise..reduce till bolt close -20
You can do -10,-15,-20 up to -40 - close to land is not always the best. Some bullet love to jump.

You have already found your load - powder charge did you ?
What is the use for those rounds ?
 
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Janeau said:
No. That have nothing to do with headspace.

Good advise..reduce till bolt close -20
You can do -10,-15,-20 up to -40 - close to land is not always the best. Some bullet love to jump.

You have already found your load - powder charge did you ?
What is the use for those rounds ?
Click to expand...

For now it's only for target, yes I have a load to start with.
 
canadianshooter said:
How does your sized brass from the same batch as the dummy round chamber without the bullet?
Click to expand...

Admittedly, I'm quite new at this game ....

However, assuming that brass has been resized full length, I'd commence my investigation per above. Chamber lengths vary and brass may not have been adequately resized for your (OP's) chamber. Even .002 shoulder bump may not be enough. Example, I've two bolt rifles, different makes but same cartridge - one rifle, I need to bump .004 for the brass to chamber and the bolt to lock/open smoothly.

Personally, I take samples of my resized brass and validate that those chamber properly in the particular rifle with bolt lock/open without issue.


Talltimber1 said:
You need a headspace gauge not the bullet comparator
Click to expand...

I concur.

Question for OP - In conjunction with the bullet comparator (using a modified case), I'm assuming that you have also used the Hornady headspace comparator to acquire your CBTO measure based on the actual case used for the reload (dummy)?
 
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rayzorloo said:
Oh really?...I assume you mean case length, I measured it at 1.92 which I've read should be 1.91-1.92.
Click to expand...

Hope I'm not misreading the above statement ....

Fired brass even if matching and/or under the prescribed "max case length" will still need to be full length resized in order to bring the case dimensions back to spec.
 
OP. I’m just thinking you need to eliminate that your brass is causing the tight chambering before you troubleshoot overall length. I’ve done a batch of brass resizing before and found that just one piece fired in another chamber, even while run through the same sizer can be a tight fit (likely shot in a much more generous chamber).
 
OP - What you are describing is common with brass that has not been resized all the way to the base. Check your resizing die set up and resize the brass, then chamber the resized brass to insure no bolt resistance. NOTE: If your bullets are jambing into the lands there will be groove marks on the bullet ... check that on the round that would not chamber.
Bullet jackets are pretty soft and jamb into the lands pretty easy, so even a .010 jamb can feel normal.
 
Sounds to me like you should make sure your brass is properly sized first. I do this method in the Eric Cortina video below... to confirm, it never hurts to take the firing pin out and the extractor also. Put the resized case in chamber and the bolt should just barely drop on it's own.


Second, When using the Hornady Modified case when determine CBTO, beware that the headspace on their modified case may or may not be the same as your rifle.

This is a lengthy video... you might skip to half way through... start to pay close attention around the 20 minute mark

 
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