7 FCP. Before I pull the trigger on this......literally

[PeteFox]

At the risk of being exceedingly boring, I have attached a graph of the data from fire forming 70 cases at the range on Saturday. All bullets jammed as previously described, not using false shoulder method. I am proceeding cautiously and trying to make data driven decisions rather than relying on opinions
I started out slow fire for about the first 15 shots, trying not to get the barrel too hot. I soon realised that it was going to take forever, and it didn't matter if I started to damage the barrel, so I started sending them down, only pausing to measure the cases. I was shooting from a bench, so it was quick.

In the attached image, blue is std case and orange is fired case lengths, shot by shot.

case length data.jpg

Findings:

-The data shows that with a hot barrel, the length of the cases was reduced markedly compared to those that were fired with a cooler barrel.
-The data also shows that a cool barrel (first three shots) case length is reduced after firing, though there is not enough data to support any conclusion.
-There was one outlier where the case length was significantly greater than all of the others (shot 7).
- In the majority of firings the case length was less than standard case length.
- All of the fired case except 2 are shorter then the recommended trim length of 2.020". Minimum length is 1.975, all are longer than this.

Measuring hot brass and comparing it to brass at room temp is not ideal, but the effect of the temperature change is only in the order of 0.001" per 30degC for a 2" case. The fired cases would actually measure 0.001-0.002" shorter at room temp than indicated.

Why would the cases would be shorter after firing at elevated temperatures? No answer here.

The question remains, where is the brass coming from to allow the case size to increase. I will mill out the outlier and measure the wall thickness.
Pete

[Fire Dog]

[font=Georgia]An interesting thread and as I am on the verge of entering the 7PRCW community {as opposed to 7FCP though I do currently shoot a rifle that Bryan Blake built in 280AI}
When it is re-barrel time I will have my spare Blake barrel {1:8.5} re-chambered with Erik C's {No neck turn} reamer, die and have already been using a "Roll Sizer©" on the 280AI.
The 7FCP & 7PRCW cartridge seems to need the extra help due it being prone to "Clickers", especially if run too hard.
Have some necked up 6.5 PRC Lapua cases + 150 ADG 7PRCW + Berger 184's to try out.
I know someone on this forum that has been through both versions of this new 7mm variant and has left them behind as not being able to get the consistent results that he needed..
This, after spending a lot of $$$$...
I am of course, hoping for a better outcome and wishing we here in OZstralia could get some N555 as that seems to be the consistent performer with this cartridge...
Until then, it is AR2213SC that seems to be the best performer. Now, if only ADI will put it out in 4Kg jugs like they once did and that you can still get in the USA. {8 pound jugs of 4831SC}
Are you neck turning? I plan to just skim turn as I have a NO Turn neck reamer and advice is to turn "After" fire forming.
Keep up with your results as I am sure that many like me are watching and hoping to get some good information on getting this cartridge to perform.[/font]

[PeteFox]

FireDog
I have a no turn chamber, but I will skim necks, just enough to take out any out of round
Pete

[PeteFox]

I went to mill out the outlier from the testing and decided to re-check the measurement, good thing, as it actually saved me a case.

I had made an error in recording the data and had left out a zero. The case did not measure 2.080" but was 2.008" and is no longer an outlier.
The corrected graph is attached. The graph looks a fair bit different from the first one because the y axis is rescaled, but all other data is the same as are the conclusions/findings.
I'll be loading some up and test at the range on Sunday
Pete

case-measure(2).jpg

[PeteFox]

OK, this is using fireformed cases, nothing super special but looks promising. Shot at 1000 yd.
First trip to the range with a decent barrel, brand new 8T Kreiger. I wasn't adjusting for wind, started with 4 mins right, just looking for elevation, down 8 clicks on the sighter, 2 mins right and then left it alone.
I also had no clue about loads because this was using 195 EOL Bergers. I went with 52gn 2209, White River primers, 0.015" jump, average 2700 fps , 10 shots with an ES of 13fps.
I'll work it up from there to about 2800.
Reason for the 195s is I have a few thousand

Screenshot_20241006_112908_Chrome.jpg

[PeteFox]

Something else I learned this week.
Don't use White River primers in your fire forming loads, they are way too hard.
About 30% will fail to fire, as the case will be driven forward leaving only a small indentation in the primer. The bullet will be driven hard into the lands and when extracting an action full of powder will result.
I don't think this would happen using the false shoulder method.
It didn't happen using Federal primers.

Pete

[Mick S]

You have been told but chose to ignore

[John Weigel]

I like the spirit of curiosity and experimentation. No value in criticizing it in the matter of this thread, and more power to whomever dares to check and recheck the foundations upon which we stand. A useful and interesting thread Pete.

[PeteFox]

I like the spirit of curiosity and experimentation. No value in criticizing it in the matter of this thread, and more power to whomever dares to check and recheck the foundations upon which we stand. A useful and interesting thread Pete.

Thanks John,
I also had another shooter contact me and he was having trouble with CCI primers, fireforming using the false shoulder method and still getting misfires.
A lot of people would rather PM me and won't post stuff up here because of unhelpful commentry. I'm just trying to add to the knowledge base here, as this is new territory for me and others.
If people want to have a go, that's OK as long as they have broad shoulders too.
Pete

[antunkov]

Hello Pete and fellow FCP users,
I’d like to hear your thoughts on FCP. What bullet and powder combinations are you using, and at what velocity? How has your experience been so far?
I’ve only had one barrel for FCP so far and used N555 powder (57.6 grains) with 180-grain Bergers.
While it performed well, with consistently low ES and SD, I regret not trying the 183-grain Sierras.

Since then, I’ve experimented with three barrels in 7-6.5 PRCW, but now I’m considering going back to FCP.
I’m especially interested in trying H4831SC powder. What has your experience been with it?
Looking forward to your insights!
Thanks! Antun

[PeteFox]

How has your experience been so far?
I’ve only had one barrel for FCP so far and used N555 powder (57.6 grains) with 180-grain Bergers.
While it performed well, with consistently low ES and SD, I regret not trying the 183-grain Sierras.

Anton
N555 ? You must be living in a different universe to me.
It's ADI or nothing here in Tas.
I've only used 2209. ES is around 13 over 20 shots. I'm happy with that. Loading 195 Berger EOL @ 2750fps using 53gn 2209.
I've now changed the 2209 lot number and Im trying to figure out a starting point.
I haven't tried 2213.
I'm not going down Sierra road again
Sorry I can't help you more.
Pete

[Fire Dog]

I'm using 2213SC in my .280AI behind Berger 184's, jumped 30, White River, running at 2'820 and getting good results.
SD just under 10fps.
Started out with them at 2'750 but just not getting the performance I wanted.
Also running a home made barrel cooler between events {thanks FC John for the video, it was cheap to make} and that keeps the barrel well under that 50*C where things start to go South.
An investment for a thermal temp sticker and less than $50 to have a cooler is one of the cheaper things to do in shooting!

How has your experience been so far?
I’ve only had one barrel for FCP so far and used N555 powder (57.6 grains) with 180-grain Bergers.
While it performed well, with consistently low ES and SD, I regret not trying the 183-grain Sierras.

Anton
N555 ? You must be living in a different universe to me.
It's ADI or nothing here in Tas.
I've only used 2209. ES is around 13 over 20 shots. I'm happy with that. Loading 195 Berger EOL @ 2750fps using 53gn 2209.
I've now changed the 2209 lot number and Im trying to figure out a starting point.
I haven't tried 2213.
I'm not going down Sierra road again
Sorry I can't help you more.
Pete

[John T]

Hello.
Pardon my ignorance, but what is the "false shoulder method"?
Regards,
John T.
21.2.25

[AlanF]

Hello.
Pardon my ignorance, but what is the "false shoulder method"?
Regards,
John T.
21.2.25

John from my recollection of a 6 Dasher, the 6BR brass neck is expanded with a .257 mandrel, then the neck sized back down using a 6 Dasher neck sizer die. This leaves a tiny shoulder between the two neck diameters, and this is what the chambered round is seated against for fireforming.

[PeteFox]

An update for those that asked.

A head up. This cartridge, despite what FCP will tell you is not for you if you don't have a lot of patience. Matt P was right, you need a lot of Kool Aid to accept all the hype this cartridge has gotten.
Whether usng the false shoulder method or jamming the bullet hard I'm still having trouble with fireforming. Misfires for about 10% of shots and sometimes big pressure, but mostly normal. I've tried all sorts of different combinations of primers, bullets and powder but still the problem persists. Pulling the trigger has become a lottery. It's giving me the total shits.

I was all ready to give it away, but Ive had a change of mind and I am going to persist.
I even bought all the SAUM gear to replace this cartridge but I now intend to keep going ahead with both.
I'm sticking with the 7FCP because the muzzle velocity ES is something I've not come across before. no matter what I did to my 284s, the high teens was as good as it got with ES and not all that often.
With the 7FCP the worst I've had (20 shots) was an ES of 13fps, but it is often in the low single digits. Im not talking 5 shot strings here which is total rubbish.

What got me going again was I found that Armaments by Design are making a hydroform die for a 7mmAzzo, which is based on the 6.5 PRC. see here >> https://armamentsbydesign.com.au/store/ ... o-7mmazzo/
The 7mm Azzo looks very similar with a slightly longer neck
Anyway John Perrott has offered to make me one for the 7FCP, so I can do all the fireforming at home without wasting diesel, powder bullets and primers and TIME.

Yes, I realize that hydroforming will present another range of issues, but that's the nature of the rabbit hole
Pete