Power Pro 300 MP Load Data

[Jeff H]

Sig220, thanks, I did see your post and have been waiting to see if anyone had thrown anything heavier down the tube with this powder. I have some 98 through 113 grain cast but 2400 works just fine with those. I have a new .311", 165 grain mould I bought for this and need to work up loads for that. I have shot 170s using Unique, 2400 and W231 but those powders will not get the most out of that weight possible. I'm hoping 300 MP shows some promise there.

Thanks again. Your results are encouraging. I may break down and pay for some jacketed bullet for this but they will be the Sierra 110 grain JHP if I do. I've had great results from them in the 30-30, .308 and '06. I don't remember how fast I had them going in the 30-30, but even in that they were quite decisive on varmints.

[Sig220]

Got back out today, for a little shooting. Temperature was up to 72. Kind of windy but wanted to shoot!!

Took the old (by now) standard load of the 147fmjbt, modified mixed cases loaded with 17.5 gns of 300-MP velocity was up a tad from when the temps were lower to a average of 2027fps. Got a chance to move to a longer range just before leaving and fired this 3 shot group at 50 yards. COAL was 2.150.



This is with a 16", 1/8 twist barrel. I think my barrel likes them!!

I did a little work on the 150 GMX's and got them to cycle with 17.5 gns, without any pressure signs. They will take some work as they like a jump to the rifling, but are long projectiles. On the chrony they were running in the high 1900fps range.

I had a few 130gn cast bullets loaded up and they were a disaster!! I had them at a COAL of 1.950 loaded with 17gns and they did not group at all....even at 25 yards!! I am suspending working with them for a while!! I had the chrony set up and they were running in the high 1700fps range.

Anyway, just having a blast loading for the 300BO, I will play a little on the 150gn class then want to work on the lighter rounds in preparation of finding a deer load me and the rifle like!!

***Remember the above loads were safe in MY rifle, and did not show any signs of adverse pressure. Your loads and your rifle add in variables that I did not account for, so drop the powder charge. Work UP to the load you want to be at...watching for adverse pressure signs.***

[Jeff H]

Nice!

I believe I have 8# heading my way. Hasn't shipped so I won't count any eggs......

I'm looking forward to seeing what it will do with the LEE C309-113 RFN and RDO (revised) 311-165.

Thanks for keeping us in the loop.

[ShortBarrelShepherd]

Thanks for giving me confidence in my own 147gr pull project with 300-MP. It's been very cool to see your results.

I have some test loads ready to go, but the range is snowed under. We might have the gentleman who owns the training facility run his tractor and plow up enough room to work.

I'm also looking forward to any information people may have about using 300-MP with Nosler Varmegeddon bullets.

[Sig220]

Had some time to burn some powder today!! Had some 150's loaded up.....to test function. Kind of guessing on whats best on COAL based on how the 147fmjbt did.

Hornady 150 interlock (BT), COAL 2.120 to 2.140, from 15.0 gns to 17.5 gns. Velocity was in the mid 1700's on the low end and the high 1900's on the other end, there were no pressure signs and they grouped well.....not as well as my 147fmjbt but well. I think the COAL could be adjusted to get better groups, but that would have to work with the powder charge.....I have found that as you increase the COAL, the velocity drops and when you shorten COAL the velocity increases.

Remington 150 Corelokt (FB), COAL 2.090 with a load of 17gns, they group really well without any pressure signs. I had a couple to try at 17.5gns, but the groups fell apart. But, it could have been me. Velocity was in the mid 1800's.

Again, I think there is plenty of room to develop loads for the 150gn class with 300-MP powder.

Now to get some lighter weight bullets in to work on .......that is in my future!! Will be taking some time away for a short recreational adventure but unless bad weather keeps me in, March should be a good month for shooting!!!

***As always, the loads mentioned above were worked up by me for MY rifle. I don't always list all of the workup, but one should assume that these loads are HOT and work up their own loads for their own rifles. Start low and increase slowly, if you seat a projectile too deeply don't be afraid to pull it and start over. You are responsible for YOUR loads, as I don't sell mine!! Be safe!!***

[Alien]

Had some time to burn some powder today!! Had some 150's loaded up.....to test function. Kind of guessing on whats best on COAL based on how the 147fmjbt did.

Hornady 150 interlock (BT), COAL 2.120 to 2.140, from 15.0 gns to 17.5 gns. Velocity was in the mid 1700's on the low end and the high 1900's on the other end, there were no pressure signs and they grouped well.....not as well as my 147fmjbt but well. I think the COAL could be adjusted to get better groups, but that would have to work with the powder charge.....I have found that as you increase the COAL, the velocity drops and when you shorten COAL the velocity increases.

Remington 150 Corelokt (FB), COAL 2.090 with a load of 17gns, they group really well without any pressure signs. I had a couple to try at 17.5gns, but the groups fell apart. But, it could have been me. Velocity was in the mid 1800's.

Again, I think there is plenty of room to develop loads for the 150gn class with 300-MP powder.

Now to get some lighter weight bullets in to work on .......that is in my future!! Will be taking some time away for a short recreational adventure but unless bad weather keeps me in, March should be a good month for shooting!!!

***As always, the loads mentioned above were worked up by me for MY rifle. I don't always list all of the workup, but one should assume that these loads are HOT and work up their own loads for their own rifles. Start low and increase slowly, if you seat a projectile too deeply don't be afraid to pull it and start over. You are responsible for YOUR loads, as I don't sell mine!! Be safe!!***

Careful with seating depth you do not want to compress 300-MP. It will give you inconsistent loads when there is an air gap. Your most consistent loads will be achieved when your bullet base is just touching the powder.

I noticed when I was trying to do subs with it that a decrease in seating depth of .1 on my OAL increased FPS by 100. That was with only 9.5 grains of powder and that sent that 208 amax at close to 1,300fps. Just a word of caution!

[Jeff H]

......Careful with seating depth you do not want to compress 300-MP. It will give you inconsistent loads when there is an air gap. Your most consistent loads will be achieved when your bullet base is just touching the powder.

I noticed when I was trying to do subs with it that a decrease in seating depth of .1 on my OAL increased FPS by 100. That was with only 9.5 grains of powder and that sent that 208 amax at close to 1,300fps. Just a word of caution!

I can certainly appreciate the caution in this situation, as the .308 bullet displaces a lot of space with respect to the volume of this case. .1" is a lot with respect to seating depths but I have ended up at least that much different from what I had hoped would work using this round (this chamber) with cast.

That raises the question about just how much air space do you think has an affect. Considering that most of the mid-weight and heavy bullets in this cartridge hang down below the neck, is your comment about the bullet base just touching the powder taking into consideration that there would be air space between the portion of the bullet below the neck and the walls of the body of the case? In a straight-wall case, your advice could be easily executed literally, but are you actually eliminating that air space I mentioned or is it, in your observations, insufficient to have an adverse affect? I can easily imagine some of the powder displacing into this air space rather than compressing at least until that space is occupied with powder.

[Sig220]

Had some time to burn some powder today!! Had some 150's loaded up.....to test function. Kind of guessing on whats best on COAL based on how the 147fmjbt did.

Hornady 150 interlock (BT), COAL 2.120 to 2.140, from 15.0 gns to 17.5 gns. Velocity was in the mid 1700's on the low end and the high 1900's on the other end, there were no pressure signs and they grouped well.....not as well as my 147fmjbt but well. I think the COAL could be adjusted to get better groups, but that would have to work with the powder charge.....I have found that as you increase the COAL, the velocity drops and when you shorten COAL the velocity increases.

Remington 150 Corelokt (FB), COAL 2.090 with a load of 17gns, they group really well without any pressure signs. I had a couple to try at 17.5gns, but the groups fell apart. But, it could have been me. Velocity was in the mid 1800's.

Again, I think there is plenty of room to develop loads for the 150gn class with 300-MP powder.

Now to get some lighter weight bullets in to work on .......that is in my future!! Will be taking some time away for a short recreational adventure but unless bad weather keeps me in, March should be a good month for shooting!!!

***As always, the loads mentioned above were worked up by me for MY rifle. I don't always list all of the workup, but one should assume that these loads are HOT and work up their own loads for their own rifles. Start low and increase slowly, if you seat a projectile too deeply don't be afraid to pull it and start over. You are responsible for YOUR loads, as I don't sell mine!! Be safe!!***

Careful with seating depth you do not want to compress 300-MP. It will give you inconsistent loads when there is an air gap. Your most consistent loads will be achieved when your bullet base is just touching the powder.

I noticed when I was trying to do subs with it that a decrease in seating depth of .1 on my OAL increased FPS by 100. That was with only 9.5 grains of powder and that sent that 208 amax at close to 1,300fps. Just a word of caution!

I am not sure my data working on supersonic loads compare to yours working on subsonic loads will compare/correlate.

Typical of fast pistol powders if you work with LOW levels of density, you can have more of a powder explosion in the case rather then powder burn. This is caused by the powder charge laying along the side of the case allowing more of the powder's surface exposed to the primer ignition. Instead of burning from one end to the other of a column of powder, you burn a field of powder all at once. If you load light charges/low density of any fast pistol powder, it would be prudent to add a filler to keep the powder bunched up on the primer end to prevent this.

None of the loads I have loaded so far would I call compressed loads. Without published scientific data, I don't think we have a true percentage of load density. In a ideal world, we would have the bullet base sitting on the powder without compressing it. Achieving this without R&D is an "art", as you will never see the seated bullet in relationship to the powder column.

I load based on my experiences of about 35 years of hand loading and watch for pressure signs like a hawk!! When working with a chrony, the SD/MD between rounds and the target groups indicates that my loads have been consistent almost to a fault. I put that information about the relationship between COAL and velocity because it was something I observed.

***Again, these loads were developed for MY rifle on my equipment. Your loads and equipment will differ, therefore you MUST in the interest of safety reduce your loads and work up, watching for signs of adverse pressures.***

Have fun, be safe!!

[Alien]

I need to edit that. It was supposed to be .01 but the principal is the same.

It does not take a lot of air gap to get the inconsistent ES and SD numbers. It is like you said not a straight wall case so I do not have anyway to give you a precise number.

I am on my 4th lb of 300-MP and I have only tested 110 - 125 gr bullets. (All Flat based) I did try with the 208 amax in subsonic but that did not work very well. Some of the 110's that I tested like the Varmintor were really short. The seating depth that I use on the Varmintor's puts the base of the bullet halfway up the neck. So when I was doing my test loads 19.5 of 300-MP is at the base of the neck, those had very large ES and SD numbers. My work up load ES and SD numbers dropped as I increased the powder. I made it to 20.2 grains when it started showing slight ejector marks. 20.2 there is no compression or air gap with that particular bullet and ES was around 18 for that particular bullet. The Sierra 2121 125 gr is a long bullet and it also showed signs of significant increase in speed with just a small increase in powder. I am overly cautious when it comes to reloading. I have no way of measuring actual pressure and there is no published data that I am aware of for 300-MP in 300 Blackout. "Just guessing here" but when the speed increases by over a 100 fps with a seating depth change or just adding .3 grains of powder there is a significant increase in pressure. Which leads me to believe that even a slight compressed load would push the pressure past the max.

The powder lots that I have tried have all been lower to my first lb in terms of FPS. That Varmintor load I referenced above on the first lot was at 2420 average fps, the other two lots have been averaging around 2350 to 2380 with the same amount of powder.

Too much rambling, I was just trying to say use caution with this powder.

[tallburnedmidget]

Alien I noticed you have posted a load with 300-MP containing chrony information in the PET load thread. I thank you for that.

There has been a lot of chatter on the forum about 300-MP since a certain rabble-rouser that is no longer with us hit the forum a couple of months ago throwing it around as an option w/out much support to back up claims or assist others who are interested in using the powder.

I would like to ask that those on this thread working up loads please post their loads WITH chrony information here viewtopic.php?f=141&t=81569

I think having a place to easily reference some 300-MP loads would help all of those out who are asking, thinking, and curious about 300-MP being a valid supersonic powder, especially for 16" carbine gas AR's. I would then be able to quickly post the link for those that ask about it