? for Kirby and other reloading guru's

[Ridge Runner]

? for Kirby and other reloading guru\'s

I've been having trouble with my 6.5 Gibbs, when I start into the top end loads with the standard powders (re22, IMR 7828, IMR 4831) I get high pressure with dismal velocity for a 29.5" barrel.
I've found that my fired cartridge neck diameter is the same as my loaded round neck diameter .288" ( my smith neglected to tell me it was a tight neck) how much should I turn the necks, is there a standard clearance? is this the likely cause of the high pressures?
H-1000 doesn't enlarge primer pockets like the faster powders do.
JS

 

[Coyboy]

Re: ? for Kirby and other reloading guru\'s

James, you are correct in your thinking. The tight necks are most likly the culprit in you high pressure signs.

I would turn the necks down 3 thousandths of and inch (.003) total neck diameter. So you would only take .0015 off of the actual neck wall. Try that and see how it works.

 

[Fiftydriver]

Re: ? for Kirby and other reloading guru\'s

James,

My rule of thumb is to make sure there is at least 0.0005" clearance between your bullet and neck when the round is fired. THat means 1/2 thou all around the bullet so your loaded neck diameters will be roughly 0.001" smaller then your fired case rounds.

A bit more comfortable is 3/4 thou all around the bullet and if your throat is quality you can even get by with 1 thou clearance.

I do not like anything much looser then this if your turning necks as it kind of defeats the purpose and often will result in your necks getting pretty thin and you have to then watch for neck splits more often and correct with annealing.

Simply put, if your loaded ammo neck diameter is 1 to 2 thou smaller then fired neck diameter, you are in the right ball park.

Keep in mind however that you need to measure this with relatively new cases. Best would be with freshly formed cases as the more a case is fired, the more it will heat temper and the result will be it will simply get spring. It will expand under pressure but then spring back smaller then chamber neck diameter so your measurements on that case will not give you a true idea of what your real fit it. Use fresh cases to get things set up and then your good to go once all is set up properly.

One other aspect to keep in mind is the base diameter of your chamber. If it is built to a standard 0.470" diameter, in most cases, this is quite a bit larger then modern 06 case head diameters are running and it will allow slightly more case head expansion then a properly fitted chamber. This is a common problem because for some reason most brass makers seem to think the 06 based rounds have a case head of a round 0.465" instead of the listed 0.470" correct diameter that most reamers are built to unless specified otherwise.


Try seating off the lands as well a bit. THis will also incease your pressure spike.

I would be suprised if RL-22 and H-4831 will not give you the best velocity to pressure ratio. Others to look at would be H-4350 and Rl-19. I would not use powders much slower then Rl-22 unless your using the real heavy bullets. For anything under 140 grains, Rl-22 will get you in most cases the most velocity performance. H-4831 will be nearly identical to that as well.

Kirby Allen(50)

 

[CatShooter]

Re: ? for Kirby and other reloading guru\'s

[ QUOTE ]
I've found that my fired cartridge neck diameter is the same as my loaded round neck diameter .288" ( my smith neglected to tell me it was a tight neck) how much should I turn the necks, is there a standard clearance? is this the likely cause of the high pressures?JS

[/ QUOTE ]

Because the fired case is the same as the loaded neck, does NOT mean you have a tight neck chamber.

The necks on my 6mmBR are the same size as the loaded rounds, and I just punch the primers and reload them.

You might have a "No turn" chamber. If the necks are 0.288", and the chamber neck is 0.289" to 0.292", the fired cases will still be the same size, because they will spring back that few 2 or 3 thou.

The thing to do before cutting the necks is the measure the chamber neck - ask your smith. He may know the dia of his reamer, or he can cast it with cerosafe for you. DON'T just start turning cases blind, without knowing where you are going with it.

.

 

[Ridge Runner]

Re: ? for Kirby and other reloading guru\'s

Just talked to the smith, after explainig the whole process, he gave me step by step instructions (which I didn't get to start with)
His instructions
adjust die for crush fit (did that)
load a round with 54 gr H-4831 and a 140 gr bullet and fire
resize fired case and load with 62 gr of re-22 and a 140 gr and fire through chrony, then call him (to see if I survive perhaps?)
can't see how this will change things but I'll give it a whirl.
RR

 

[Dave in Idaho]

Re: ? for Kirby and other reloading guru\'s

JS,
The destructions that came with my Romain built 6.5 Gibbs (way back when) said to run through a FL .270 sizer die, trim neck as far back as the length of the neck when it is formed (he enclosed one for a sample), turn the neck to .012" thickness.
Size through a 6.5 Gibbs die for crush fit (a neck turned and sized down piece of brass was included).
Load with 55gr H4831 140gr bullet (into the lands if necessary),then fireform.
I don't know about the neck thickness for your chamber but that worked out great for mine. I still have the two sample brass that were included with my dies and rifle.
I will post a pic of the sample brass later tonight.
HTH
Dave

Gibbs Brass Pics: Left is pre fireformed. Resized and neck turned. You can see the bump of the false shoulder. Post fireformed brass is on the right.

 

[Ridge Runner]

Re: ? for Kirby and other reloading guru\'s

thanks for the info dave, don't know if I've posted this but I fireformed with 11 gr of unique/cow/tp and my necks are .015" thick.
Ray told me I was enlarging primer pockets from fireforming, this goes against all I know about reloading, the shoulders are still round.
He instructed me to fireform with 54 gr of H4831 then load up a charge of 62 gr of re22 and shoot it.
any load above 60 gr that I have tried has blown the primer pocket. what puzzles me is what is different about the different methods of making cases that would change this? the .003" of neck thickness?
the only powder I can run above 3150 with my cases is H1000, anything else and the pocket is gone with 1 shot.
JS

 

[Fiftydriver]

Re: ? for Kirby and other reloading guru\'s

James,

I do not think you have mentioned what bullet weight you are using? If your using 140-142 gr bullets, your velocity is not all that bad. My 6.5-06 AI will get 3050 fps in a 26" barrel with the 140 gr A-Max. Your longer barrel will get you more but loaded head to head, I have always found the AI rounds to run within 50 to 75 fps of the Gibbs.

You may just have a slow barrel.... It happens.

As far as you loosening the primer pockets on forming with corn meal. Are your primer pockets loose when you seat a new primer after fireforming? If they are not, OBVIOUSLY, you are not loosening your primer pockets using this forming method.

It is true you never want to run pressures high enough with corn meal to see any change in primer fit but you know this the instant you reseat a primer. If they are tight, you are not doing anything wrong.

Anyway, let us know what bullet weights your using and that will help determine if you have a real problem or not.

To say every rifle chambered for the 6.5 Gibbs will take 62 grains of powder is hard to believe with the variations in barrels, bullets, case volumes and powders.

I think velocity claims get us into alot of trouble. There was a time that the 257 STW was claimed as a 4100 fps round with the 100 gr barnes bullets in a 28" barrel. Most of this "crap" was started by a smith by the name of Ferguson down in Texas I believe.

For years he stood by his claims even though even his customers could not get these levels of velocity without ruining cases on the first firing.

Finally, just this winter I got a call from one of his X customers that said he finally got him to admit that he can easily reach this level of performacne but cases only last one firing. And that he loaded his personal rifle to the 3800-3900 fps range for longer case life.

Again, if your using a 140 gr clas bullet, you are not doing to bad for this chambering despite what many smiths may tell you. Your case necks may be to snug and that will cause pressure spikes but other then that, listen to your rifle, it will tell you when pressures are to high. I have found on many occasion you get much more meaningful information from listening to your rifle then others that offer opinions on your rifle!!!

Kirby Allen(50)

 

[Ridge Runner]

Re: ? for Kirby and other reloading guru\'s

yeah kirby I'm shooting the 140's, I know with the h1000 I can get decent velocity (3200 fps), but I have to go 4 gr over published max. just trying to figure out that if he's so sure 62 gr of re 22 will work then it must not be a hot load, but 61 gr fireformed with my method will be deprimed when you eject the case. If I go above 3100 with any of the optimal powders (imr 4831, re22, imr 7828, h4831) then the cases are junk after 1 firing.
guess what I'm trying to figure out is what would fireforming with a bullet change vs. the COW method, does it thin the necks opposed to using cow?
JS

 

[Dave in Idaho]

Re: ? for Kirby and other reloading guru\'s

JS,
Seems odd to me that simply using COW would alter primer pockets at all. BUT, try the H4831 and 140's. At this point it can't hurt to see what happens.
Dave

 

[Ridge Runner]

Re: ? for Kirby and other reloading guru\'s

dave, just saw you pics, I asked ray about turning necks and he said I shouldn't have to, but my necks are .015" thick, but I think I will and see if that makes a difference.thanks
JS

 

[Black Diamond 408]

Re: ? for Kirby and other reloading guru\'s

I belive my old P.O Ackley loading manual says to use 20grns of Unique for fire forming the 6.5-06 AI
Iv'e tried lots of differnt loadings for fire forming brass and never seen one loosen a primer pocket. Not saying it wount.

It sounds like you either have a tight bbl or the necks are a bit snug.

Dave

 

[Dave in Idaho]

Re: ? for Kirby and other reloading guru\'s

JS,
I don't know if I ever asked you but what brass are you using?
I do agree with Ray that if your necks are .015" then they should be fine, but who knows. Turn them and fire form a few with the H4831 then fireform a couple without neck turning and see if it makes a difference.
Dave

 

[Ridge Runner]

Re: ? for Kirby and other reloading guru\'s

using rem brass as per rays instructions, I dug out the cases which ray sent with the dies and the necks are .012"
but all mine are .015" even the 50 win brass that I have fireformed.
personaly I can't believe that fireforming with unique/cow/tp is harming the pockets, the shoulders look like a weatherby radious so there isn't alot of pressure there.
Ray told me to trash all my cow ff'd cases and buy new ones, just trying to figure out if the cases can be salvaged, thinking about getting some nosler brass if I can get the thing straightened out.
JS