6.5 PRC 156 load development

[L.Sherm]

I dont ever look at mag box length as determining if I can get more case capacity, to me its all about getting out of the donut area and adjustability for accuracy to the lands if I need too

 

[Sending156s]

I am not agreement with you guys on the internal ballistics side of this yet. I have not been able to prove that adding a minute amount of internal volume to the case via moving the bullet .050 further out is worth any velocity change worth taking note of. Where things become more abrupt is if you are actually compressing the charge and then you can see gains and lower pressure for sure. I don't see anyone running 60 grains or less at 2.920-3.00 coal compressing any of the popular powders. As for speed I ran a 130 berger in my 22" barrel at 3150 at .5 grains under max. Max load, slight ejector mark, showed 3200. I ran this bullet at 2.950 COAL just like all the others. Just not convinced a long or medium action is gaining anything. A 2.80" box or mag would not be ideal but many of the internal oem mags seem to run

I am not agreement with you guys on the internal ballistics side of this yet. I have not been able to prove that adding a minute amount of internal volume to the case via moving the bullet .050 further out is worth any velocity change worth taking note of. Where things become more abrupt is if you are actually compressing the charge and then you can see gains and lower pressure for sure. I don't see anyone running 60 grains or less at 2.920-3.00 coal compressing any of the popular powders. As for speed I ran a 130 berger in my 22" barrel at 3150 at .5 grains under max. Max load, slight ejector mark, showed 3200. I ran this bullet at 2.950 COAL just like all the others. Just not convinced a long or medium action is gaining anything. A 2.80" box or mag would not be ideal but many of the internal oem mags seem to run much longer than 2.80.

Brent, all that matters is that you are happy. As long as you stay away from heavy high BC bullets you will be fine. I do challenge you to find one ballistics expert such as Brian Litz that will not tell you seating bullet bearing surface below the case neck/shoulder junction is detrimental to efficiency. Attached is a pic from an old post when I was deciding what action to build on.
Best wishes & happy shooting!

 

[BrentM]

Brent, all that matters is that you are happy. As long as you stay away from heavy high BC bullets you will be fine. I do challenge you to find one ballistics expert such as Brian Litz that will not tell you seating bullet bearing surface below the case neck/shoulder junction is detrimental to efficiency. Attached is a pic from an old post when I was deciding what action to build on.
Best wishes & happy shooting!

Never said it wasn't. The problem is that everyone claims it is a massive change it's not unless you are seating on the extreme side which is what the article refers too. I've done the testing and know that .050 is not doing much in the prc. Sure .250 is worthy of consideration and exactly why the Winchester got the Norma treatment. I'm all ears if anyone has the numbers to show .050, actually gained x over y in the prc. Would love to see someone else actually take the time to do it like I did. In the end, I see zero reason to run anything else than a 2.950 coal and short action until proven otherwise. I'm not
Trying to be difficult, just want someone step away from an article being taken out of context about minimal seating depth changes. Now, if you run a long action and a 240 throat, yeah now you have a lot to work with over a 188

 

[Sending156s]

Never said it wasn't. The problem is that everyone claims it is a massive change it's not unless you are seating on the extreme side which is what the article refers too. I've done the testing and know that .050 is not doing much in the prc. Sure .250 is worthy of consideration and exactly why the Winchester got the Norma treatment. I'm all ears if anyone has the numbers to show .050, actually gained x over y in the prc. Would love to see someone else actually take the time to do it like I did. In the end, I see zero reason to run anything else than a 2.950 coal and short action until proven otherwise. I'm not
Trying to be difficult, just want someone step away from an article being taken out of context about minimal seating depth changes. Now, if you run a long action and a 240 throat, yeah now you have a lot to work with over a 188

I have not even read the article. I just used common sense as is indicated on the drawing I attached.
Why am I going to be concerned over things like difference in bullet seating tension, shoulder setback, etc. and not care that we have 80 thou of bullet bearing area buried in case volume area.
I'm glad you are happy with what you went with and I'm happy with what I went with. Beyond that we will just agree to disagree.
You & fam have a wonderful evening!
Lynn

 

[BrentM]

I have not even read the article. I just used common sense as is indicated on the drawing I attached.
Why am I going to be concerned over things like difference in bullet seating tension, shoulder setback, etc. and not care that we have 80 thou of bullet bearing area buried in case volume area.
I'm glad you are happy with what you went with and I'm happy with what I went with. Beyond that we will just agree to disagree.
You & fam have a wonderful evening!
Lynn

I don't disagree with you but the point is what did it do for you or the cartridge? What did you achieve? I would do the same if I understood there was any true benefit to the process. What I am asking for is education information and not one person has shown data that suggests a saami spec prc is restricted when running heavy bullets. Intuitively it seems it is and I whole heartedly agree the bot tail to shoulder junction is a solid match but the prc was really designed around the 140 and comp. The 150 class bullets weren't even available yet. Here is a 135 loaded to 2.953 coal. This thing has about the same profile as the 140 and 147 eld.

 

[L.Sherm]

I thought the O.P. question was about the 156?

 

[TAZMAN]

Great conversations guys but there are two many variables in this thread now. There is SAUM data and others that may be a bit confusing for some. I have not tested my new loads yet @ 55 Grains 2.950 OAL CCI200 primer 156 Berger and Hornady twice fired brass. I had my knee surgery yesterday so I am hobbling around for a day or two!!lol

I did test the 54.5 grains 4831SC 153A-tip and 215 primer though. Shows some promise but I could tell and distinct difference in reoil and sound with this load. There is still a very small distinct ejector swipe but this brass has been worked hard since it was my test brass with high pressures for both loads. This is all in a 6.5 PRC 22 inch barrel.

 

[BrentM]

That is correct, there are too many variables to claim that your seating depth is creating the issue. Powder lot, moisture content in the powder, chamber, etc. There is nothing yet to suggest your issue is the seating depth of the bullet.

What I would like to see you try is a lower charge, as you have already planned, and seat the bullet to the lands in a couple rounds and test. Additionally, I think you need velocity data to make any of this valid. I have had differing lots of retumbo create issues for me in my 6.5-284. At any rate, velocity is going to tell you a lot more than just bolt lift and witness marks on the brass alone.

Last, I would also encourage you to measure the base of the case and make sure your case is around .530 or less. If you are at .531 plus you have an issue with the brass expansion.

 

[TAZMAN]

Once I get healed up a little I will get the Lab Radar out and do some further testing to see if I can tune it a little.

 

[central iowa couple]

Hi guys, watching this thread closely. I have a Rem long action rifle in 6.5 prc I've been working on loads for. I also have various other rifles also in 6.5 prc (ruger and browning ). The Remington has the throat reamed out longer so the 140 accubonds are seated with the base of the bullet before the boattail is at the neck/shoulder junction. I didn't think this was a big deal when i bought it on this forum last year. Boy was i wrong. Lol. I've picked up a bunch of re26 and developed loads with the 156 berger. Amazing. Today my loads are 60 gr of re26, the 156 seated .040 of the lands for a cbto of 2.390. This loads is 3092 fps. I had it hotter at 3112 fps with no pressure signs but 60 grains is literally 1 hole. Didnt think i needed hotter when i looked at the ballistics at 1000 yds. Now if it was a bit lighter rifle I'd carry it for elk. Lol. The 6.5 prc is really amazing with the 156's.

 

[highdrum]

I have two prc in tikkas that are cut to 225fb, 156s 35k off lands have just the boat tail in powder space. 24" barrels do over 3075-3100 w/ N570. Pressure isn't until 3200fps.

 

[central iowa couple]

Forgot to mention this is with Hornady brass. Some of them are on the 7th loading. I have adg brass but that's saved for my wife's browning

 

[central iowa couple]

How much 570 are you loadingm i realize i need to start lower.....but i haven't tried my 570

 

[highdrum]

How much 570 are you loadingm i realize i need to start lower.....but i haven't tried my 570

The accuracy is pretty good 3070-3100fps, 60.4-61gr. 62.3gr is where psi started to show, 3195fps. Accuracy was good at 3145fps 61.4gr but the node was pretty small.