My 6.5 Gibbs has a tight neck, well tighter than I like them, case life is dismal, a PITA to for cases for but it shoots like a house-a-fire, velocity is a lil low I think (3280 fps with a 139 lapua/29.5" barrel)
the only way I've successfully made cases is to use unique/cormeal/tp, then they are good for 1 firing (lose the pocket) I fireform, turn necks to .010 then load.
The guy who built its instructions were, resize to a crush fit, load with 54 gr of IMR 4831 behind any 140 gr. first batch or rem cases were fair.
His next instruction was load with 62 gr of re-22 and a 140 (first round blew primer broke extractor) so I turned the necks but still lost the pockets after 1 firing. cut the charge back to 60 gr using CM/TP fireformed new win cases, lost the pockets after 1 firing.
Got 100 new nosler cases, the smith told me I was swelling the pockets with cornmeal, so necked to a crush fit loaded the 54 gr 4831 behind a 140fired 9 cases the 10th blew the primer, broke the extractor, the first 9 were ruined also.
Now my question, will opening up the throat help this? if so what will it do to velocity? not holding anyone to anything just wanted to hear experienced opinions.
loaded unturned outside neck dia is .289
turned loaded outside neck dia is .285
fired turned neck dia is .288
fired unturned outside neck dia is .290
also had it shooting decent with H-1000, but went up to 67 gr with no signs of pressure at about 3220 fps, but max load is sposed to be 62 gr. Am I expecting too much or is 62 gr of re-22 too hot for this cartridge?
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Last edited by Ridge Runner; 11-25-2007 at 11:48 AM.
What case are you using to fireform? I guess the important question is what is the correct trim length your reamer is setup for? The original Gibbs cartridges were all off the 30-06 case(2.494) the overall case length in the books I have list 2.500 for the gibbs. If your using 270 brass(2.540) and not trimming them before loading you may be crimping the bullet in the case in the throat of the chamber. How much powder were you using with the cornmeal method? Did the cases show taper at the end of the neck?
labs, the smiths reamer was made of a 270 case length, the cases came out fully formed, just slightly rounded shoulders, I was using 11 gr of unique.
johnny, Rocky gibbs designed the cartridge on a '06 case, his design called for the shoulder to be pushed foreward far enough to allow one caliber of neck length. The smith had his 6.5 reamer ordered at 270 case length to better stabilize the long 140-155 gr hi bc bullets
Took the rifle to a local smith today, was broken down and chamber cast made, the lead seems to be longer than the cases, the neck diameter of the casting was .292, seems that in order to get case life I'm just gonna hafta load it down.
any other thoughts?
The barrel is a kreiger 1/8, are they known to be slow? I mean if I load it down to 3150 fps, I'd be better off with a 6.5/06 AI wouldn't I?
I remember when you were having that built about a year and a half ago - I was getting a 264 WM at the time.
If you have a .292" chamber neck, and a .289" loaded unturned outside neck, you would up with a "no turn neck", not a "tight neck"... and when you turn off another 4 or 5 thou, the necks are pretty thin to survive a 7 thou expansion when fired.
I have also found that neck turning a case causes the necks to harden - I wound up tossing out over 900 neck turned cases a while back when I loaded them up, and let them sit for a while, and they split on their own (without ever being fired :( ) The original neck was 0.014" and I turned them to 0.010". They had the classical "T" split - down the neck along the bullet, and then around the base of the bullet, forming a "T", for almost half of the circumference of the neck.
I would suggest that you load a bullet in a Fire Formed case that has an unturned neck, blacken the neck, and chamber it to check that there is adequate neck clearance - then turn the cases the minimum amount to clean them up, and then anneal them.
That might work out for you.
Also... as Lazy said - that RL-22 load might be too hot if you are loosing cases from primer pocket expansion.
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Last edited by CatShooter; 11-26-2007 at 12:41 PM.