Good idea, I'll do that. Thanks!
COAL using CBTO from Hornady OAL gauge significantly shorter than book COAL?
- Thread starter reformedcitykid
- Start date
Help Support Long Range Hunting Forum
Does the bullet drop easily into the modified case as-is? If not, then you need an expander mandrel/die that will allow you to do so.
Last edited:
Your current CBTO measure is less than the saami freebore measure for the 6.5cm (2.140") so very good chance the bullet is getting hung up at the chamber mouth or in the freebore region BEFORE the lands (throat region). Two ways I've run into the same issue are (1) dirty/carbon fouling…rifle needed a good cleaning of freebore and throat area..lots of c4 and brushing (2) new rifle that needed to be polished or in my case broken-in (~200 rds) then cleaned thoroughly. Bore scope can help diagnose the first. I had inconsistent measurements in that instance. With the second type, hammers (but not Bergers) were getting a consistent short reading on a new barrel. The first 200 rds broke the barrel in..likely deburring or polishing a spot where they were hanging up. Hope this helps
X2^^^^^^^ been doing it for years...K.I.S.S.! But with the ejector in.
Are you maybe forgetting to re-zero the calipers after removing the comparator?
Amazing how people don't read! 
I use a caliber diameter mandrel.. ie .284, .308 etc. run it through the brass, the brass will pop back .001-2.
Start a bullet in it, put it in the rifle and use the bolt to seat it into jam. Extract it and measure accurately with an ojive bushings. I typically do 3 for each bullet type. Rarely are they off by more than a couple of thousands. This method has been excellent for me for years… very accurate "to jam" measurement.
Lube the ojive where it will contact the lans.
Goods luck
Start a bullet in it, put it in the rifle and use the bolt to seat it into jam. Extract it and measure accurately with an ojive bushings. I typically do 3 for each bullet type. Rarely are they off by more than a couple of thousands. This method has been excellent for me for years… very accurate "to jam" measurement.
Lube the ojive where it will contact the lans.
Goods luck
8x68s
Well-Known Member
I had a Hornady 260 Rem measurement case that wouldn't accept a bullet at all. They must have forgotten to run the oversize mandrel thru the case at production. I tried to fix it with a .270 mandrel but it was too much.
lancetkenyon
Well-Known Member
Did you reset zero on your calipers with and without comparator installed?
slikmrc
Well-Known Member
Give the modified case mouth a little inside neck chamfer and see if that helps. Also you could load up a dummy round to Sierra's OACL and try it in the gun.
He's already mentioned gents that the neck of the case gauge is too small and binding. He needs to open it up some. The end
Gents, glad to report back with some good news! As suspected, it was an issue with the modified case neck. I sanded it down until the bullet slid freely, and took 10 measurements:
2.3230"
2.3270"
2.3260"
2.3275"
2.3270"
2.3260"
2.3250"
2.3230"
2.3245"
2.3260"
For an average of 2.3256" aka 2.3255"
Any recommendations how far off the lands to start loading? I've read from .01" to .04", if anyone has a compelling argument one way or another please let me know!
Once again, thanks for everyone's input!
2.3230"
2.3270"
2.3260"
2.3275"
2.3270"
2.3260"
2.3250"
2.3230"
2.3245"
2.3260"
For an average of 2.3256" aka 2.3255"
Any recommendations how far off the lands to start loading? I've read from .01" to .04", if anyone has a compelling argument one way or another please let me know!
Once again, thanks for everyone's input!
FireFlyFishing
Well-Known Member
I've found from my testing and not forums…0.020" to start.
