300 PRC testing

[Rhovee]

It's better to have an oversized bore compared to underside!

 

[yorke-1]

I 6 " dropped tubed RL25 and N570 into new Hornady 300 PRC brass today and got right at 94 grs of either powder into a case .
That RL33 is getting it done with the 208 gr-er . I'm gonna get and try some I'm mine .

I just filled a fired case with RL 25 and got 96.1gr in there without a drop tube.

I'd bet your over pressure with those loads with RL33. What's your barrel length? And as far as fire forming , what dies are you using ? What capacity is your once fired versus resized brass?

My barrel is 26" and I'm using a Redding FL sizing die. I measured the H20 capacity of a fired case and got 97.7gr. A sized case has a capacity of 97.6gr.

It's better to have an oversized bore compared to underside!

That's what I was thinking! I've had tight bores before and they were difficult to work with.

 

[Weatherby Fan]

I measured a new ADG Case with R33 to the top of the neck and got 92.2 grs
I measured a new Lapua case and got 95.2, a measured a once fired Lapua case and got 95.5grs

I'm just having my number 8th 300 PRC built now every one was accurate with 86-86.5grs of R33 in a slightly compressed load of R33 and 245gr Berger's loading at 3.720" to 3.750" depending on mag box length, target rifle single shot no mag box
So when I seen 96.0grs I thought it was a typo

Just curious if you could please measure or tell us your OAL touching the lands with a 245gr Berger if you have one or a 225gr ELDM

Thanks
Don

 

[CA48]

I just filled a fired case with RL 25 and got 96.1gr in there without a drop tube.


My barrel is 26" and I'm using a Redding FL sizing die. I measured the H20 capacity of a fired case and got 97.7gr. A sized case has a capacity of 97.6gr.


That's what I was thinking! I've had tight bores before and they were difficult to work with.

My 30 SM has about 3 more grains h20 than the 300 PRC. A fired cases measures 97.4gr so your H20 cap seems a little high?

 

[yorke-1]

My 30 SM has about 3 more grains h20 than the 300 PRC. A fired cases measures 97.4gr so your H20 cap seems a little high?

What brand of brass are you using?

 

[yorke-1]

I just measured a new, unfired, Lapua case with a spent primer seated upside down and the capacity is 95.8gr of H20.

 

[Bilser]

I recently picked up a Seekins Havak PH2 in 300 PRC as a bit of an impulse buy. I haven't bought a new factory built rifle in nearly 15 years, so this purchase even surprised me. My only real issue with the PH2 is that Seekins uses a 1:10" twist barrel. That wasn't enough of an issue to deter me from buying the rifle though. For the $1500 I paid for the gun, I could put a new barrel on there and still be money ahead compared to building a comparable rifle.

I plan on playing with bullets in the 200-215gr range as well as some lighter monometal bullets. I'm starting to work on loads now that I have about 100 rounds through the barrel while breaking it in and forming brass. I thought I'd post up some of my results just in case somebody else can find the information useful. I'm starting with the 208gr ELDm, just because I have a few hundred of them to work with. I'll add other bullets as I have time to try them. I'm not chasing velocity, just good accuracy and velocities appropriate for a case this size within a specific bullet weight range from a 26" barrel. I'm happy with 200-215gr bullets in the 3000 fps range.

All of these loads will use the same specs, except for powder charges:
- Lapua 300 PRC brass (fireformed to this chamber)
- Fed 215m primers
- Hornady 208 ELDm
- OAL 3.720"

These velocities were all taken with a Magneto Speed chronograph. The conditions were 39° and raining while testing. This particular rifle doesn't shoot well with the Magneto attached, so I didn't pay much attention to group size. All powder charges were hand weighed. None of the charges listed showed any signs of pressure in my gun. Bolt lift was the same from the lowest charge to the highest with each powder and the primers don't show any signs of flattening.

Reloader 33
91.0gr- 3026 fps
91.7gr- 3000 fps
92.5gr- 3056 fps
93.2gr- 3058 fps
93.9gr- 3103 fps
94.6gr- 3143 fps
95.3gr- 3139 fps
96.0gr- 3190 fps

Reloader 26
77.0gr- 2875 fps
77.7gr- 2863 fps
78.4gr- 2923 fps
79.1gr- 2960 fps
79.8gr- 2972 fps
80.5gr- 3025 fps
81.2gr- 3065 fps

H1000
78.0gr- 2799 fps
78.7gr- 2820 fps
79.4gr- 2851 fps
80.1gr- 2909 fps
80.8gr- 2951 fps
81.5gr- 2966 fps
82.2gr- 2961 fps

I was really surprised by the velocity with RL 33. This isn't a powder I've seen or heard much about in the 300 PRC, but I'll work with it a little more. I'd be thrilled if I can get good accuracy and over 3100 fps with a 208gr bullet. The velocity increases were a little erratic at the low end but became more consistent as the charges increased. I've seen this with RL 33 in the past too. It just seems to perform better at near max levels. I only have 3 pounds of RL 33 on hand, so I may not spend too much time burning components if I can just find a load that will shoot reasonably well (for a factory rifle).

RL 26 showed the same erratic velocity increases as RL 33 at the low end and became more consistent as charges increased. It looks like there's a bit of a flat spot around 2960 fps, which is where I expected to see a node. I'll try a few loads with charges up around 83.0gr and see if I can hit a higher node as well as shooting for groups at around 79.5gr. I would love for RL 26 to work in this gun since I have almost a full keg on my shelf. I haven't had any luck with this powder in any other chambering, so I'd love to find a use for it.

H1000 was the most predictable powder I tested. The velocity increases were the most consistent with a pretty clear node around 2960 fps. This powder also showed the best group with the Magneto attached, but that really doesn't mean anything. I have enough H1000 to last a while if that is the best powder, so that wouldn't be a big issue.

Thanks for posting that information. I had a rifle built in 2020 during lockdown in 300prc with a Proof Research 26" barrel and a tenacity action. I have been shooting Hornady 212 ELD-X at 2917 twist of 1 in 10 at 1000 ft elevation and little humidity in AZ. Best group at 100 yards 3/4 inch. I would like to find a load that would give me .5 or less MOA for this rifle. My son and are gathering the components to shoot lighter bullets he also just got a 300 PRC by Christensen Arms a Ridgeline. I will watch for future posts from this group to see what you all are doing. By the way this is my very first reply or post, so thank you again for your post.

 

[WildRose]

Thanks for posting that information. I had a rifle built in 2020 during lockdown in 300prc with a Proof Research 26" barrel and a tenacity action. I have been shooting Hornady 212 ELD-X at 2917 twist of 1 in 10 at 1000 ft elevation and little humidity in AZ. Best group at 100 yards 3/4 inch. I would like to find a load that would give me .5 or less MOA for this rifle. My son and are gathering the components to shoot lighter bullets he also just got a 300 PRC by Christensen Arms a Ridgeline. I will watch for future posts from this group to see what you all are doing. By the way this is my very first reply or post, so thank you again for your post.

The 300 PRC was specifically designed for the heavy for caliber bullets. To build one for lighter bullets really disserves the cartridge.

 

[Weatherby Fan]

Thanks for posting that information. I had a rifle built in 2020 during lockdown in 300prc with a Proof Research 26" barrel and a tenacity action. I have been shooting Hornady 212 ELD-X at 2917 twist of 1 in 10 at 1000 ft elevation and little humidity in AZ. Best group at 100 yards 3/4 inch. I would like to find a load that would give me .5 or less MOA for this rifle. My son and are gathering the components to shoot lighter bullets he also just got a 300 PRC by Christensen Arms a Ridgeline. I will watch for future posts from this group to see what you all are doing. By the way this is my very first reply or post, so thank you again for your post.

Try R26 and H1000, They both are great powders for the 300 PRC, R26 usually will give same velocity as H1000 using 1 to 2grains less powder,
For me 75.5-76.5 of R26 has been great, 76.0 best
H1000 77.0 to 77.7 grs has been very accurate for me as well
I used 210 Berger's, 212 ELDX, 215 Berger's, 225 ELDM with those loads
Please start lower and work up as every rifle is different

 

[CA48]

What brand of brass are you using?

ADG, I didn't realize you were using Lapua. I'd like to get a few pieces to compare.

 

[Earnhardt]

The 300 PRC was specifically designed for the heavy for caliber bullets. To build one for lighter bullets really disserves the cartridge.

I thought the 300 PRC was designed/throated by Hornady with a onger free bore, to seat bullets out farther towards the lands, to keep the bullet from being seated into the powder (to gain powder capacity)
Whether it is a 168, 185, 215 or a 245 grain bullet...

 

[WildRose]

I thought the 300 PRC was designed/throated by Hornady with a onger free bore, to seat bullets out farther towards the lands, to keep the bullet from being seated into the powder (to gain powder capacity)
Whether it is a 168, 185, 215 or a 245 grain bullet...

It was especially developed for the long heavy for caliber bullets for long range competition shooting.

You're going to have a really hard time getting one throated for the long/heavy bullets to shoot the light ones accurately because of excessive freeborn.

 

[yorke-1]

It was especially developed for the long heavy for caliber bullets for long range competition shooting.

You're going to have a really hard time getting one throated for the long/heavy bullets to shoot the light ones accurately because of excessive freeborn.

We'll find out how it works when I get time. I have a handful of the 153gr Apex Afterburners on hand and I'm going to order some 160g Hammer Hunters to try as well. I might get some Cutting Edge bullets to try too.

 

[Earnhardt]

It was especially developed for the long heavy for caliber bullets for long range competition shooting.

You're going to have a really hard time getting one throated for the long/heavy bullets to shoot the light ones accurately because of excessive freeborn.

Ok…
So the light for caliber bullets (less than 200 grain ) that I'm using in my 300 rum that I'm shooting at about Mach 6.9, at less than one half MOA, that doesn't meet that criteria?

That 300 rum is throated for 215 and 230 Berger bullets