357 Maximum Pressure Concerns

[steve@357maximum.com]

Hi, my name is Steve Cutter and I am the owner of the website 357Maximum.com.  I have found that Graybeard Outdoors is an excellent site and have enjoyed reading many of the forum discussions on different topics.  Certainly, a lot of information here. 

I have been following the posts on pressure concerns with loads using AA1680 that exceed the Accurate Arms top listed load with the 180 gr. Hornady SSP bullet.  Something I would like bring attention to, is that the top load for this combination is nowhere near the top pressure listed by SAAMI.  It is actually 7000 C.U.P. lower.  Johan Loubser of Accurate Powders explained to me that when testing, they generally stop at a certain compression ratio and that is why this top load listed is so far under the SAAMI maximum.  In my own experience, my cases were not even expanding enough to seal the chamber at the 26.5 gr. load resulting in soot on the cases after firing.  As Johan explained, this powder is on the slow side for the .357 Max.  I’m sure this is why my loads performed so much better at the 28.0 gr. level.  Many of us are shooting this round in guns with chambers that have been opened up.  A lot of these chambers have long throats.  My Ruger No. 1 is a good example of this.  These longer throated chambers allow much longer cartridge OAL’s which reduce pressure.

I am in the process of assembling rounds for laboratory pressure testing in mid-Sept.  These will all be loaded with 28.0-30.0 grains of AA1680.  I plan on including the Hornady 180 SSP, Hornady 180 XTP, and Hornady 200 gr. FTX.  Once I receive the data, I plan on posting the results on my website.  Hopefully, this scientific data will provide some insight rather than relying on estimates which understandably makes many cautious handloaders nervous.

Best Regards and Good Shooting,
Steve Cutter

[Airsporter]

Outstanding 

[quickdtoo]

Welcome aboard Steve! Sounds like a nice project to get some actual factual data, but the SAAMI MAP for the 357 Max is 40kpsi, they don't use the old CUP method any more, and you state in your article that Johan estimated the pressure of the 28gr load to be between 43-45kpsi. Since safety in an SB1 framed firearm(not an Encore) is what the concern was in JSLHandgunner's thread,  I confirmed with him that the breech force of a 45kpsi load is safe in the SB1 Handi since it's less than that of the 44mag which is factory available.

Thanks, looking forward to you test data.

Tim

http://357maximum.com/developing-a-load/

Johan estimated the pressure of my 28.0 grain load to be 43,000-45,000 psi and well within the caliber’s envelope and the T/C gun I am using.

http://www.frfrogspad.com/miscellk.htm

http://www.lasc.us/SAAMIMaxPressure.htm

http://www.handloads.com/misc/saami.htm

http://www.leverguns.com/articles/saami_pressures.htm

[Dinny]

Steve,
  It's good to see you here. This info couldn't come at a better time as I am working loads for my Maxi, just in time for deer season this year. 

Don't forget about your fellow Hoosiers.    

http://www.gboreloaded.com/forums/index.php/board,249.0.html

Thanks, Dinny

[revbc]

Welcome aboard Steve,

Looking forward to the results of your experiment.  I think your are probably correct with being able to loadem hotter, because I get a little smut to in the 25-26gr range.

However just couldn't resist posting this group at 97 degrees F and about 85% humidity.  It's 25.7 aa1680 with a 180gr xtp topper @ 100yds

Bobby

[steve@357maximum.com]

Bobby,
That's an excellent group!  I am curious, do you still get the residue on the outside of the fired cases with that load when shooting in extreme heat?
Steve

[revbc]

Steve,

I went back and looked at these, they did not seem to have as much as I'm used to seeing.  Some had a little bit right at the neck, but it did not run down the case as it usually does.

Bobby

[randy_68]

Hi, Steve,
Your website is what convinced John and myself to experiment a little with these loads.  We did find that the soot would go away at 28.5 gr of AA1680. And that this was a very accurate load. We pushed the envelope a little but we thought it would be safe and it appears to be. We will be looking forward to the results of your testing.

Thanks, Randy

[aromakr]

Are you crimping the bullets, or seating without a crimp?
Bob

[JSLHandgunner]

We are not crimping.

Hello Steve,
  Like Randy said, you article is what convinced us Ind. folks to try the Max. I have a lot of experience in the Hornady 180ssp that I load for my Rem. xp-100. This bullet prevails to be the most accurate out of my H&R Max as well. As stated in my lated post, The hotter I loaded it the better it shot. But I was kinda concerned with the factory SB1 frame. Right now, I dropped my handload down to 28.5gr 1680. It is extremely accurate. I shot 3/4" group at 146yards with 2 of 3 shots in the same hole. I have not had a chance to shoot it past this yet. Randy, my Dad, and myself, are using the same handloads with the same results. Any more info. would be appreciated. Thanks, John
 

[steve@357maximum.com]

Hi John,

On the crimp note, I found my velocity to be identical (to the exact fps) between crimp and no crimp for a 10-shot average.  In the testing I did, with the Encore, I had a little better accuracy with crimping so that is what I do.  However, if a greater number of accuracy samples were taken, I would bet the accuracy difference would be negligible.  In this comparison, I think the neck tension on the .358 bullet gives more than adequate resistance for good powder ignition and in reality the crimp neither helps or hurts.

Earlier on this thread, Tim explained what was going on with opinions of the two different frames available for the Handi-Rifle.  I know very little about the Handi-Rifles so I am better off not commenting on this.  I will say that Johan Loubser of Western Powders Inc. (Accurate) is a very knowledgeable and well respected ballistics expert and I would trust his opinions.  It would be interesting to hear what NEF has to say about this.  Hopefully, some of the pressure testing I have planned will also help us to understand this more.  It does appear to me that you are cautious in your experimenting and have a good understanding of the associated risks.

Last year the load I used in my Ruger No. 1 was 29.0 gr. of AA1680 with a Hornady 200 gr. FTX bullet.  Because of my rifle's long throat I am seating the bullets out to where I am only capturing .187" of the bullet in the case.  The bullet is resting on the powder but not compressing it.  This helps keep pressure down.  With this load I am getting 2020 fps from the 22" tube and accuracy is very good.  I took (3) does last season and none of them were long shots.  I did not recover any bullets but the longest any deer went was about 50 yards.  I especially like the high ballistic coefficient of this bullet.  I'm not saying it's better than the 180 gr. SSP but I really like it.

Best Regards,

Steve