The reason for my HIGH Prssure

[Greg Duerr]

I noticed today that My fired cases the necks were still so tight that I could not even begin to push a bullet into the neck..........................All necks on spent cases should have expanded enough in the chamber to release the bullet and then spring back a little ...... but still leaving the neck loose so that it needs to be resized .

This is the reason that I have been pulling my hair out with super high Pressure and thinking it was the Cases, bullet seating depth, the Lot of powder etc.......................

I guess that this is called Tight neck...............and usually that means that your cases need to have the outside turned down.............

Well, I don't want to turn my necks...................the Beginning .243 loads in the Ackley formed cases were already getting into High Pressure...........

It even busted the Sako extractor today........................The Cartridge case neck had no place to expand to.....................

Is this suppose to happen on Custom RIfles or is this a Chambering issue.............>>??

 

[AZShooter]

Is this supposed to happen on Custom Rifles or is this a Chambering issue.............>>?? It can happen. The gunsmith should have told you the chamber reamer has a tight neck.


I think the gunsmith is responsible for the damage to your rifle. I would visit him and show him what you discovered. I would ask him to correct the issue and fix the extractor. He needs to learn how dangerous the situation is that he created!
Also find out what the chamber neck dimension is and compare it to your loaded necks.

This is one of many reasons why I quit using the gunsmith's reamer and order my own. I decide the fit and whether I want to turn the necks or not.

You might find that another manufacturer has thinner brass.

Turning the necks is not that big a deal. I use K and M products and am very happy with the quality and accuracy.

Let us know how you resolve this issue.

 

[Edd]

What is the neck diameter of a loaded cartridge?

 

[AZShooter]

Edd yep that's what I said above: "Also find out what the chamber neck dimension is and compare it to your loaded necks"

A true Ackley Improved would be set up to shoot SAMMI 243 win ammo so brass comes out fireformed. Most Ackley chambers are headspaced roughly .004" shorter than the standard chambering so you get a crush fit on a factory case when you close the bolt. This ensures good fireforming without the case moving in chamber.

Usually SAMMI spec chambers have adequate bullet release dimensions to accommodate the varying thicknesses of brass made by different manufacturers but after reading the min and max on the SAMMI spec, shown below, the reamer may be within the specifications and still cause you pressure issues for lack of bullet release.

SAMMI 243 spec calls for a reamer .277" minimum dia neck with cartridge maximum of .276" neck diameter. That is calling it close if any brass has neck wall thickness variances.
http://www.saami.org/pubresources/cc_drawings/Rifle/243 Winchester.pdf

Sure seems like the 243 win min chamber and max brass diameter are too close. I wouldn't want to work with .001" total neck clearance on anything but a BR rifle.

It will be interesting to hear what you find out Greg. Keep us informed.

 

[elkaholic]

This is a common problem and happens more often than it should! It happened with my buddy on a custom 300 WSM. I agree with the guys above. The smith should correct ALL the problems free of charge and feel fortunate that something worse didn't happen. If it were me, in the future I would use a different smith. This is pretty basic safety.......Rich

 

[Greg Duerr]

I started out with Lapua brass then learned that it is thick so I used the Smith's recommended brass, Winchester, which is suppose to be a lot thinner. I still had very tight necks......................I will mic the loaded and fired and find out.

It shoots the Standard Ackley cases to .2 and .3 in Fire Forming......and with really light loads for the standard .243 the Ackley cases shoot well under.5

 

[Edd]

What kind of scales are you using and how did you calibrate them?

 

[Greg Duerr]

I use a RCBS Charge Master and I calibrate it everytime I use it

 

[Edd]

I use a RCBS Charge Master and I calibrate it everytime I use it

I've never used one of those. How do you calibrate it? Did you ever measure your case necks?

 

[bigngreen]

A novice needs to remember that a custom chambered rifle requires more attention to details at the start of reloading for it because it is built for performance and held to tight specs. Your brass, sometimes your bullets and your own personal methods of loading may not spec out to the way the reamer and rifle were built.
You need to do a very exacting inspection when you get a rifle, your brass, dies and bullet are not the same as the smiths, you need to mic everything, my first rounds from any rifle are strictly to measure up how things are working with the components I'm using. Breaking an extractor is a sure sign you skipped important steps in your loading process and then kept going, I would suggest sending the rifle back to the smith with brass and bullets and pay him to do a complete load work up for you.

I just got a new reamer that I spec'ed for .004 neck clearance on the brass I had, built a rifle this weekend and bought some factory rounds to go break it in with and found it has .003 smaller necks from the same manufacture of brass so with that brass it's more of a factory neck and more than I would want for a precision rifle but it will shoot what ever it's feed which this one needs to so it's fine and it shoot stupid good with my test load. Point being that I'll have three reamers for this one chambering and bullet just because of brass specs!!!

 

[elkaholic]

I agree with Rhian that anytime you are dealing with a custom rifle, wildcat etc., there are certain basic measurements that must be adhered to when doing your loading. Custom rifles and wildcat cartridges are only as good as the person in control of them. On the other hand, I still think it is the responsibility of the smith to make very clear to the customer that, in this case, the neck is too tight to use certain brass without turning. You should also know exactly what that dimension is and mic your loaded rounds to give at least .003" clearance. I fault the smith if you were not made aware of this, but you should ALWAYS check your own work if you are dealing with custom stuff, and to a certain degree, even if you are not......Rich

 

[Greg Duerr]

The Charge master has a process you go through with weights to calibrate it each time you use it.....................................................

 

[Greg Duerr]

I talked to the Smith today and was very impressed with what he had to say............
Lets just say I have a lot to learn and made some mistakes. He wants me to send
my rifle back to him and he will do what is needed and ship it back.
Im also sending him five of my berger 105's from my lot and five fired cases and five loaded one............to check them out.

As frustrating as this has been it has been a positive learning experience. Unless you know someone that is very knowledgeable In Advance Reloading we all learn through trial and error.
What I did learn is that When your Smith suggests that you fire form using 40gr of H4350 and a 105 seated like the Dummy round he sent . DO IT....................For me it was just that H4350 was no where to be found ..................

The way this rifle shoots I just can not imagine getting another rifle that he did not build.........................The problem was ME. The problem I might have created was a Carbon Ring, ...................Don't ask me what that is.............

Greg

 

[elkaholic]

I talked to the Smith today and was very impressed with what he had to say............
Lets just say I have a lot to learn and made some mistakes. He wants me to send
my rifle back to him and he will do what is needed and ship it back.
Im also sending him five of my berger 105's from my lot and five fired cases and five loaded one............to check them out.

As frustrating as this has been it has been a positive learning experience. Unless you know someone that is very knowledgeable In Advance Reloading we all learn through trial and error.
What I did learn is that When your Smith suggests that you fire form using 40gr of H4350 and a 105 seated like the Dummy round he sent . DO IT....................For me it was just that H4350 was no where to be found ..................

The way this rifle shoots I just can not imagine getting another rifle that he did not build.........................The problem was ME. The problem I might have created was a Carbon Ring, ...................Don't ask me what that is.............

Greg

A carbon ring usually occurs right ahead of the case neck and is accentuated by too much trim. I usually trim my cases by only .005". This helps reduce the chance of that happening, but you may have to trim a little more often. Once in awhile I soak the chamber/neck area with a rag soaked in Kroil for a day or two and then take a bore brush that is neck sized and rotate in the chamber to break any carbon loose. It usually takes quite a few rounds before this is a problem, but as I mentioned above, firing cartridges with too short necks will speed it up. I am glad you got things figured out and that you had a smith who was willing to help you out........rich