Fireforming to AI: Full power Improved loads?

[1911fan]

I've always read that to fireform the parent case to an Ackley, you should use a small charge of fast powder, and have the bullet solidly in the lands.
In the new Varmint Hunter, there is an article on Improved cartridges, and the author quotes P.O. Ackley as saying, "Fire forming should be done with a full charge because light loads have a tendency to shorten the cases... appearing to be fully formed though they may have .050" or more headspace..." The author apparently fireforms with full power AI loads.

Anybody tried fireforming with full Improved loads?

On another note, in the same article gunsmith Darrell Holland as saying, "When chambering to Improved cartridges be sure to have .004 to .005" compression on the Go gauge. The bolt should not close on the Go gauge in a correct chamber."
So have I screwed up by chambering to accept an AI go gauge? The gun shoots well and the brass is reacting nicely.

Discuss.


1911fan

 

[montyb]

Re: Fireforming to AI: Full power Improved loads?

the AI go gauge will have the correct "crush" built into it's dimentions, so you are good to go in that respect. what they are saying, is that a go gauge for the parent (not improved) version of your chamber should not "go". the AI chamber is a tad shorter to allow firing the un-formed cases without slop.

and i use near max or max loads for the PARENT case for FF, but have not used the AI loads for this. so i can not say yea or nay.

 

[1911fan]

Re: Fireforming to AI: Full power Improved loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 1sikpupi</div><div class="ubbcode-body">The AI go gauge will have the correct "crush" built into it's dimensions, so you are good to go in that respect. What they are saying, is that a go gauge for the parent (not improved) version of your chamber should not "go". The AI chamber is a tad shorter to allow firing the un-formed cases without slop.</div></div>

Interesting, hadn't read it that way. I'm thinking about loading one unimproved case with my AI load and pulling the trigger, just in the interests of science. I just can't figure out why NOT to. Anybody?


1911fan

 

[DIBBS]

Re: Fireforming to AI: Full power Improved loads?

I'm no expert, but I do have experience with a .243AI & 22-250AI & fireforming .220 Russian cases to 6PPC. The gunsmith set up the chambers so that there's ~.002" crush fit on the parent case. For my fireforming,I have had the best results using a max load for the <span style="font-weight: bold">parent</span> case with the bullet jammed in the lands.

I'm wondering if your AI load might be more of a proof load-what are we looking at 1.5-2.5 grains of powder difference? When I tried lighter FF loads, the shoulders weren't fully formed, and I think you only get one chance to do a good job with fireforming cases.

I did also try a fast powder with a wax plug on fireforming .220 Russian to 6PPC in the basement (that <span style="font-weight: bold"><span style="text-decoration: underline"><span style="font-style: italic">reeeelllyyy</span></span></span> loosens the dust up from the rafters)but got rounded case shoulders with this experiment.

Kinda disturbed the pets too.

 

[1911fan]

Re: Fireforming to AI: Full power Improved loads?

Apples and oranges, as fireforming and AI loads are using different powders, though both have a little jam. AI load is at Nosler's recommended max, moly bullet, no pressure signs and shoots great.
I tried a book fireforming load and got rounded shoulders, so I bumped it up and got better results. Interestingly, I did not change seating depths from forming to AI loads. Still have a slight jam.


1911fan

Off to slaughter a chuck!

 

[TEAMSENDIT]

Re: Fireforming to AI: Full power Improved loads?

I use just a grain under max for fireforming my 22-250ai and it seems to be working great. plus currently my fireforming loads are more accurate than the improved loads.

 

[JRWALLSIII]

Re: Fireforming to AI: Full power Improved loads?

I use a near max load for the parent case in my Ackleys. I have never had a forming problem at all. I have also never in had negative results (as far as accuracy) with a fireformed load. Usually the accuracy in both is great the velocity is just better in the improved version

 

[Phylodog]

Re: Fireforming to AI: Full power Improved loads?

I've been forming my .223AI brass with 25 grains of RE15 and jamming 75gr BTHP's and AMAX's into the lands. Great accuracy and the brass is forming very nicely.

 

[Greg Langelius *]

Re: Fireforming to AI: Full power Improved loads?

Technically, every time you load a case for the first time, you're fireforming. Now my thinking is, what purpose is served by fireforming at a different operating pressure from what the case will be subjected to ever after? I just load and go with the 'standard' load.

 

[RussW1911]

Re: Fireforming to AI: Full power Improved loads?

I like to have atleast 500 formed brass for my Ackleys. I work up a load at full strength and shoot until I have all my brass, then switch over to my standard Ai load. Nary a problem with it and loads for fireforming give up nothing in the accuracy department.

 

[ggarrett1911]

Re: Fireforming to AI: Full power Improved loads?

I've always used a near max or max load for the parent case and jammed the bullet in the lands for fireforming, like many others here have stated as well. Had excellent results and no rounded shoulders this way like some I've seen that used pistol powder and some form of buffer. Plus the fireforming loads usually shoot pretty damn well to boot!

 

[QRE23]

Re: Fireforming to AI: Full power Improved loads?

I'm having a 243AI built right now and many a 243AI owner has told me their standard 243 loads shot nearly, if not as well, as their AI loads when they were forming for their AI brass.

 

[brdeano]

Re: Fireforming to AI: Full power Improved loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 1911fan</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 1sikpupi</div><div class="ubbcode-body">The AI go gauge will have the correct "crush" built into it's dimensions, so you are good to go in that respect. What they are saying, is that a go gauge for the parent (not improved) version of your chamber should not "go". The AI chamber is a tad shorter to allow firing the un-formed cases without slop.</div></div>

Interesting, hadn't read it that way. I'm thinking about loading one unimproved case with my AI load and pulling the trigger, just in the interests of science. I just can't figure out why NOT to. Anybody?


1911fan </div></div>

Okay....I've read the posts up to this one, but not the rest.

I HAVE tried to run loads from my AI'd cases in my FF loads and they were too hot. I didn't think they would be since some of that pressure was being used to form the cases...right???....wrong!!! The full power AI loads were too hot for the FF loads. That was my experience with them, yours may vary.....

 

[Starvin]

Re: Fireforming to AI: Full power Improved loads?

You could always consider hydraulically forming your cases.

 

[V-Ref]

Re: Fireforming to AI: Full power Improved loads?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Brad Arnett</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 1911fan</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 1sikpupi</div><div class="ubbcode-body">The AI go gauge will have the correct "crush" built into it's dimensions, so you are good to go in that respect. What they are saying, is that a go gauge for the parent (not improved) version of your chamber should not "go". The AI chamber is a tad shorter to allow firing the un-formed cases without slop.</div></div>

Interesting, hadn't read it that way. I'm thinking about loading one unimproved case with my AI load and pulling the trigger, just in the interests of science. I just can't figure out why NOT to. Anybody?


1911fan </div></div>

Okay....I've read the posts up to this one, but not the rest.

I HAVE tried to run loads from my AI'd cases in my FF loads and they were too hot. I didn't think they would be since some of that pressure was being used to form the cases...right???....wrong!!! The full power AI loads were too hot for the FF loads. That was my experience with them, yours may vary..... </div></div>

I had this same question...how much case pressure does the act of fireforming the case consume?

In my application/experience the use of AI loads during fireforming lead to excessive velocites and pressure.

Even published max load data may lead to excessive pressures depending on seating/depth and the ogive/land dimension.

Do you have a chrono or access to one? Use of a chronograph is my personal opinion of the best sign of pressure, then bolt lift, primers, etc. Especially with Improved chambers, as you a going into "uncharted" territory in terms of loads that haven't been proven with a pressure barrel.

Are you obtaining published load data velocities with the SAAMI max loads during fireforming?

On another point.....After fireforming, I found using 50% of the new increased case capacity as a safe/conservative new max load to head towards with the fireformed cases from the published max loads.
Example: SAAMI case at 3.600 COAL prior to fireforming holds an avg of xxx grains of water to overflow
Published max data is 92 grains for the SAAMI chamber and 3.600 COAL.

Fireformed cases hold xxx + 6 grains of water to overflow. 3.875 COAL Seating depth increases useable case capacity another 2.5 grains. Total increased case capacity from SAAMI is 8.5 grains.

New "max" load in fireformed cases WAS NOT 8.5 grains ABOVE published max...but rather approx 50% of the 8.5 grains of gained case capacity could be used with the specific powder/seating depth/bullet/gun combination in that situation.

Disclaimer-Be conservative, don't blow your gun, your buddies or yourself up.

Improved chambers are a hoot!