7x57 ai Questions

[Werewolf]

So my buddy and I have decided to build a 7x57 ai, because we love the parent round and have most of the parts to do it. My main question is about load data. I have been searching the web, this site, and my personal library and info seems hard to come by. I am very interested to see if anyone has experience with this round, and would be willing to share some of their favorite loads. Alternately please share places or books where CURRENT info may be found. Please realize that I will be starting low and working up for safety's sake. I would just like to have some idea about where the ceiling is before I start. i know things can get hairy fast with ai's. Thank you for your replies, and feel free to chime in with your experiences so that others can benefit, there isn't much good info out there.

[mutwagn]

Ammoguide list this cartridge. http://ammoguide.com/cgi-bin/ai.cgi?sn=fNqrpuwoqB&catid=434
There are 8 loads listed. Also a google search showed information on it on several forums on the net.
HTH Andy

[Werewolf]

Ammoguide doesn't show loads unless you are a member, and I did google searches and read all the posts about how great the round is, or why would you ever do that, but very little useful load data. I only posted here after becoming frustrated with my own searches. Thanks anyway.

[GaCop]

Start you load testing using 7X57 mid range charge data and go up from there. I load for a 223AI, when I form brass, I use 223 data just below the max charge w/o problems, the brass is well formed and loads are very accurate at 100 yards.

[Werewolf]

Thank you Gacop. That was really my plan all along, my real question was if any one had loaded this round before and was willing to share so I could have an idea of what a max is for this round that I should'nt go over. For instance if I was using a loading manual I wouldn't go over X pressure because it is getting unsafe. With the tendency of ai rounds to hide pressure signs until they are already pretty high I was just looking for a safe upper limit before I start rather than trying to reinvent the wheel. Thanks to both of you for replying.

[GaCop]

Yes, not being able to read pressure signs until it's almost out of hand is a down side to the AI cartridges. I keep my loads at the upper end of the 223 Rem load date but have not gone over the max load. Use the upper end 7X57 data and you'll stay out of trouble. I wish there was decent AI data available to make life easier.

[Blue Avenger]

short and not so sweet... if you see pressure signs YOU ARE OVER!!! not close to over!!!

[Joe O]

For my 243AI ,I fireformed with a near max load for the parent 243 case (virgin brass),then worked up from there with different powders and bullets.All powder charges,for the AI, should be higher than max loads in the parent case.Work up slowly.You'll know,by pressure signs, when to back off.

[jelsr]

I have a 257AI on an Arisaka and have never seen pressure signs. I also have a 7X57AI on a 98 Mauser that will show bolt lift resistance when nothing else is out of spec. Nothing radical, just enough that you need to put your thumb against the scope for the initial lift. 6gr of bullseye and a case full of cream of wheat with some wax for sealer will give sharp shoulders for fireforming and much cheaper than a bullet. Still trying to find what it prefers but 46gr of H4350 and 145gr Speers would be a safe starting load. 48.5gr loads showed mid 2800fps and 49gr showed initial bolt lift resistance.

[358Hammer]

http://www.accuratereloading.com/757ackley.html


Great cartridge and this site has a bunch of data.

Neal

[Werewolf]

I shelved this idea a year ago, but thanks to Hammer's input I may resurrect this project. My 280ai is almost done now, so on to the next! Thanks!:cool:

[BillPa]

What manufacturer-weight bullet, barrel length, etc?

One example...

Powder: RL-15
140gr. Nosler BT H
Calculated Powder Charge = 44.4 grains
Load Density = 86.0%
Charge/Bullet Weight Ratio = 0.317
Estimated Muzzle Velocity = 2815 ft/sec
Estimated Chamber Pressure = 49198 CUP

(%) (grains) Wt. Ratio (ft/sec) (CUP)
---------------------------------------------------------------------------
75 38.7 0.276 2453 36566 OK
80 41.3 0.295 2618 42328 OK
85 43.9 0.314 2783 48090 OK
90 46.0 0.331 2942 53631 High Pressure
95 49.0 0.35 3106 59393 High Pressure
100 51.6 0.369 3271 65154 High Pressure

[jelsr]

38.5 gr H4350, 145 Speer Spitzer, Douglas bbl. 26"