300 prc load development

[Wide Glide]

208/225s only seem to shoot well between 0.015 to 0.025 off in my 300wm

 

[OutsideSeth]

Hey appreciate the input for sure. Yeah I've never seen 4 different powder charges shoot almost exactly the same same and poi. But those charges on a 600 yard ladder had almost no vertical spread at all.

One possible cause for this that a chronograph could help pinpoint would be incomplete powder burn. If you are using a very slow powder like I am in this cartridge you may hit a velocity "ceiling" where the powder is still burning after the bullet leaves the barrel. Depending on barrel length and powder speed this could be what is happening.

 

[Wide Glide]

One possible cause for this that a chronograph could help pinpoint would be incomplete powder burn. If you are using a very slow powder like I am in this cartridge you may hit a velocity "ceiling" where the powder is still burning after the bullet leaves the barrel. Depending on barrel length and powder speed this could be what is happening.

That would be my guess. It was the only reasoning I could think of for a similar experience I had recently. I am used to pretty short nodes with a noticeable Change in poi When switching from one level to another in half grain increments. While doing no developments for my 300 WinMag recently though I noticed as I moved from one target to the next the POI was pretty consistent in distance from the bull's-eye And I was happy to see it but didn't think much about it until I set up the Chrono and aimed at the same diamond target at 100yd through 5x 5-shot strings 76.0/76.5/77.0/77.5/78.0.

 

[Nmbowhunter06]

That would be my guess. It was the only reasoning I could think of for a similar experience I had recently. I am used to pretty short nodes with a noticeable Change in poi When switching from one level to another in half grain increments. While doing no developments for my 300 WinMag recently though I noticed as I moved from one target to the next the POI was pretty consistent in distance from the bull's-eye And I was happy to see it but didn't think much about it until I set up the Chrono and aimed at the same diamond target at 100yd through 5x 5-shot strings 76.0/76.5/77.0/77.5/78.0.

View attachment 204710

So how did you correct that problem? Did the chrono show speeds that weren't lining up with what you were seeing on the target? I thought when I did this that I would be finding a node maybe .5-1 grain of powder not 1.5 grains and not the way they grouped at 100 yards all the same size and poi

 

[Nmbowhunter06]

One possible cause for this that a chronograph could help pinpoint would be incomplete powder burn. If you are using a very slow powder like I am in this cartridge you may hit a velocity "ceiling" where the powder is still burning after the bullet leaves the barrel. Depending on barrel length and powder speed this could be what is happening.

Now how did you correct the problem?

 

[OutsideSeth]

Now how did you correct the problem?

A chrono would help you validate if this is indeed the issue. It sounds like you tested at both 100 and 600 yds. At 100 yds it would be very difficult to tell the difference between charges in a magnum cartridge they are going to be so close together at that range. At 600 yds you should be seeing a difference.

There are a lot of things I don't know about the load you are working up, but if it were me and there were no pressure signs and I was happy with the velocity; I would choose the charge where the plateau starts and go with that. If I wasn't happy with the velocity then I would choose a faster powder with mfg published load data for 300 PRC and work up with a faster powder.

I am a little surprised you would be seeing this in 300 PRC as I am using probably the slowest powder with published load data (LRT) and am getting a complete burn in a 26" barrel. That said I think with LRT in a shorter barrel I would likely be seeing what you are.

Powders with mfg published load data for 300 PRC
IMR 7828
Alliant RL-26
H4831
Alliant RL-25
H1000
RETUMBO
Ramshot Magnum
Ramshot LRT

Suggested published mfg load data:

http://blog.westernpowders.com/wp-content/uploads/2019/10/300-PRC.pdf

https://www.hornady.com/assets/site/hornady/files/load-data/300-prc-v2.pdf

 

[Nmbowhunter06]

That would be my guess. It was the only reasoning I could think of for a similar experience I had recently. I am used to pretty short nodes with a noticeable Change in poi When switching from one level to another in half grain increments. While doing no developments for my 300 WinMag recently though I noticed as I moved from one target to the next the POI was pretty consistent in distance from the bull's-eye And I was happy to see it but didn't think much about it until I set up the Chrono and aimed at the same diamond target at 100yd through 5x 5-shot strings 76.0/76.5/77.0/77.5/78.0.

View attachment 204710

A chrono would help you validate if this is indeed the issue. It sounds like you tested at both 100 and 600 yds. At 100 yds it would be very difficult to tell the difference between charges in a magnum cartridge they are going to be so close together at that range. At 600 yds you should be seeing a difference.

There are a lot of things I don't know about the load you are working up, but if it were me and there were no pressure signs and I was happy with the velocity; I would choose the charge where the plateau starts and go with that. If I wasn't happy with the velocity then I would choose a faster powder with mfg published load data for 300 PRC and work up with a faster powder.

I am a little surprised you would be seeing this in 300 PRC as I am using probably the slowest powder with published load data (LRT) and am getting a complete burn in a 26" barrel. That said I think with LRT in a shorter barrel I would likely be seeing what you are.

Powders with mfg published load data for 300 PRC
IMR 7828
Alliant RL-26
H4831
Alliant RL-25
H1000
RETUMBO
Ramshot Magnum
Ramshot LRT

Suggested published mfg load data:

http://blog.westernpowders.com/wp-content/uploads/2019/10/300-PRC.pdf

https://www.hornady.com/assets/site/hornady/files/load-data/300-prc-v2.pdf

right now the load is as follows
-h1000
-fed 215m
-75.5-77 are the powder charges I'm working with.
-rifle is a bergara wilderness 24" barrel 1/9 twist.
The ladder was shot at 600 and took the charges with lowest vertical and shot them at 100 and here we are.

 

[Wide Glide]

right now the load is as follows
-h1000
-fed 215m
-75.5-77 are the powder charges I'm working with.
-rifle is a bergara wilderness 24" barrel 1/9 twist.
The ladder was shot at 600 and took the charges with lowest vertical and shot them at 100 and here we are.

Lol i was also shooting 24" with 225eldm 76-78 gr h1000. I backed the load down to 76 grains I was still getting the same accuracy. The change in velocity was so minimal that it wasn't worth the two grains of powder. I don't have my data book with me but if I remember correctly it was less than 30 ft per second

 

[OutsideSeth]

right now the load is as follows
-h1000
-fed 215m
-75.5-77 are the powder charges I'm working with.
-rifle is a bergara wilderness 24" barrel 1/9 twist.
The ladder was shot at 600 and took the charges with lowest vertical and shot them at 100 and here we are.

I don't have personal experience with H1000, but it appears to be just above Ramshot Magnum and RETUMBO in burn rate. That load is right in the range for the published data for 225gr ELD-Ms and in the same barrel length. I would not expect unburned powder to be the problem given the published data, but I am not sure what else could cause this.

 

[Nmbowhunter06]

Lol i was also shooting 24" with 225eldm 76-78 gr h1000. I backed the load down to 76 grains I was still getting the same accuracy. The change in velocity was so minimal that it wasn't worth the two grains of powder. I don't have my data book with me but if I remember correctly it was less than 30 ft per second

So I'm not completely crazy then lol. Everyone I've talked either says to scrap it or they think I'm crazy for not understanding what charge to go with lol. I told a buddy that I was willing to bet my pay check that if I loaded 1 of each powder charge they would all group and you wouldn't even know. Honestly I was gonna pick 76.0 since it's almost in the middle and play with seating depth.

 

[Nmbowhunter06]

I don't have personal experience with H1000, but it appears to be just above Ramshot Magnum and RETUMBO in burn rate. That load is right in the range for the published data for 225gr ELD-Ms and in the same barrel length. I would not expect unburned powder to be the problem given the published data, but I am not sure what else could cause this.

My impression is that this rifle just has a really wide node and that seating depth will fix the group size but I'm also a novice reloader so that's why I reached out here.

 

[corsteve]

have a christisen arms 300 prc an went with a proofrserce barrel chambered to 7mm/300prc 75.5 h1000 195 bereger elite hunter 3030 fps just need to have custom dies built from ptg in white city ore plus a die reamer 300prc never did shoot well but new gun 3 shots touching each other

 

[Nmbowhunter06]

Oh this wild cat shoots better than the original 300 prc? I might go with a 30 nosler on my next rifle which I'm gonna have a custom one built. This 300 prc is a bergara wilderness rifle I've had good luck with bergara rifles just wish they made a carbon rifle.

 

[Nmbowhunter06]

Well I appreciate all the information everyone gave me. So been playing with seating depth on these 225 eldms and settled on .030 off the lands and 76.5 grains of h1000. I've shot everything in between 76.0-77 and they have all shot pretty dang similar at 100.My chamber measured 2.976 and so that puts my Coal at 3.717. It's shooting pretty tight at 600 yards. They have all been under moa at 600 with the tightest one around 1.5" and the biggest one being a little over 5".