300 PRC

[wboggs]

That thought process is only valid if you plan on shooting a SAAMI chamber with SAAMI ammo. I would venture to guess most people asking questions are more interested in the case itself rather than how it was chambered/throated. I could be wrong. Most of the high performance 28 Noslers you are seeing are custom throated because IMO Nosler blew it with the throat design. The Case is another story.

Most high performance shooters are aware of all the ways to take a specific case and add all the variables to it, including custom chambering. To reproduce someone's results, you have to reproduce how they achieved them. Then you have variations in the barrel, brass, powder, etc. With that in mind, you can make some good assumptions and then test your equipment and see what it actually produces. I would think 25-50fps difference with these large cases will be seen. That is, many times, what the different caliber will produce.
Bill

 

[FrankG]

Could you clarify a little more? Is this with bullets seated at 3.34"? The two SAAMI chambered/throated 300WMs I have had allowed seating 215s at 3.7".

I don't know measurements off hand with the 215's but for reference in a SAAMI min. spec. chamber a 220SMK at 3.500" overall length you will be jamming the bullet into the rifling on a brand new barrel/chamber. If memory serves me right you will be jamming it about .020" into the rifling.

I know the 215 vs. the 220 are profiled a little different but I don't think it would be enough to make a .200"+ difference.

As a guess if you are seating the bullets out to a 3.700" overall length and you have a SAAMI min. spec. chamber I don't see you being able to close the bolt. I could be wrong but as a guess I don't see it happening. You have to have a non SAAMI spec. chamber. If you have a factory barrel/chamber they can run larger than SAAMI.

As reference....Dave here in the shop has loaded a ton of 215's in .300WM. He has a custom chamber with a much longer throat (I mean way longer than SAAMI). He seats his bullets to an overall length of 3.720". That's only .020" longer than you and again he has a custom chamber. There is no way his ammo will chamber in a SAAMI min. spec. barrel/chamber set up.

I pulled the chamber reamer print that we used for Dave's gun. His free bore length is .235". We had the reamer made to his sample round which had a 215 Berger in it.

Dave is running a 28" long barrel and is only getting mid to upper 2800's. Think he is at like 2850 to 2870fps and he even says he is stepping on the load. He is running the same powder as me (even same lot code), same primers as well. His powder charge is .5gr more than me and I'm faster velocity wise still.

Later, Frank

 

[FURMAN]

I am telling you I have had two SAAMI 300wms(still have one) 215s touching the lands are 3.7" oal give or take a few thousandths. Now I did not chamber them my self and I did not see the reamer. All I can say is it was two different gunsmiths and they touch the lands within a few thousandths of each other.

 

[wboggs]

I am telling you I have had two SAAMI 300wms(still have one) 215s touching the lands are 3.7" oal give or take a few thousandths. Now I did not chamber them my self and I did not see the reamer. All I can say is it was two different gunsmiths and they touch the lands within a few thousandths of each other.

Look up the SAAMI chamber specs for .300WM, .300WSM, and .300 PCR. I believe you will see that you do not have a SAAMI spec. .300WM chamber. That is not bad but it reinforces what Frank has been trying to tell you.
Bill

 

[FrankG]

I am telling you I have had two SAAMI 300wms(still have one) 215s touching the lands are 3.7" oal give or take a few thousandths. Now I did not chamber them my self and I did not see the reamer. All I can say is it was two different gunsmiths and they touch the lands within a few thousandths of each other.

You could have a standard SAAMI spec. chamber in regards to the area for the case but the throat could be modified from SAAMI.

As an example we use the .300 A191 chamber reamer a lot. It's a standard case spec. but has a modified throat. We use this a lot with guys who shoot longer heavier bullets. The reamer we used in Dave's gun....his throat is another approx. .125" longer on the free bore than the A191 chamber reamer.

Unless you have the reamer or can get a print from the gunsmiths that shows what reamer spec. was used to cut your chamber....we are all only guessing.

Anytime we do a fitting job for a customer....if the customer requests a copy of the drawing of the chamber reamer we give it to them. I have a whole book just on the chamber reamers we have. I even have some of them saved on my computer at work so I can email them as well.

In regards to .300wm reamers we have the following: SAAMI min. spec., .300wm Obermeyer, .300wm A191, .300wm Bartlein (this is the really long throat reamer we used on Dave's gun).

Later, Frank

 

[wboggs]

You could have a standard SAAMI spec. chamber in regards to the area for the case but the throat could be modified from SAAMI.

As an example we use the .300 A191 chamber reamer a lot. It's a standard case spec. but has a modified throat. We use this a lot with guys who shoot longer heavier bullets. The reamer we used in Dave's gun....his throat is another approx. .125" longer on the free bore than the A191 chamber reamer.

Unless you have the reamer or can get a print from the gunsmiths that shows what reamer spec. was used to cut your chamber....we are all only guessing.

Anytime we do a fitting job for a customer....if the customer requests a copy of the drawing of the chamber reamer we give it to them. I have a whole book just on the chamber reamers we have. I even have some of them saved on my computer at work so I can email them as well.

In regards to .300wm reamers we have the following: SAAMI min. spec., .300wm Obermeyer, .300wm A191, .300wm Bartlein (this is the really long throat reamer we used on Dave's gun).

Later, Frank

I suggest we move on to a discussion of this new cartridge and it's characteristics. How is the Hornady brass and how does it shoot with various barrel twist options, loads, accuracy, match shooting, factory rifles, and many other topics. Information should be forth coming as experience with it accumulates.
Bill

 

[FrankG]

Bill, My gun is holding right at 1/4moa for vertical at a 1k. I went from the Hornady 225 ELD-M's to the 230 SMK. The SMK hit at the bottom of the X ring with the same load as the Hornady's and I had the Hornady's printing right at a center X. When I wen to the SMK I had only 11 rounds loaded as I was doing testing only and shot 7 X's and 4 10's. I didn't make any corrections to the scope while I was shooting the SMK. One of the 10's was shooter error and if I would've done my part right should've been a X and at least two of the 10's was from the wind picking up a little. I wasn't worried about the wind. I was more interested in the vertical.

My barrel twist is a 1-9. Standard .300x.308 bore and groove size and 5R rifling.

SD's where coming in at 6.5 with my load. At the target (electronic targets) the bullets where hitting the target at 1900fps.

Later, Frank

 

[wboggs]

Bill, My gun is holding right at 1/4moa for vertical at a 1k. I went from the Hornady 225 ELD-M's to the 230 SMK. The SMK hit at the bottom of the X ring with the same load as the Hornady's and I had the Hornady's printing right at a center X. When I wen to the SMK I had only 11 rounds loaded as I was doing testing only and shot 7 X's and 4 10's. I didn't make any corrections to the scope while I was shooting the SMK. One of the 10's was shooter error and if I would've done my part right should've been a X and at least two of the 10's was from the wind picking up a little. I wasn't worried about the wind. I was more interested in the vertical.

My barrel twist is a 1-9. Standard .300x.308 bore and groove size and 5R rifling.

SD's where coming in at 6.5 with my load. At the target (electronic targets) the bullets where hitting the target at 1900fps.

Later, Frank

Interesting that you have a 1-9 twist. The Hornady web site shows an increased BC with a faster twist barrel. I had not noticed that before. Sierra seems to be recommending a faster twist for their new smks. With the larger cases and high velocity many shooters are using a 1-10 in
308 and 1-8 in 6.5mm and getting good results. I have a 1-7.5 on my 6.5 PRC but I used it because there may be future bullets that require it. Also, many shooters are concerned about bullet integrity at high rotation velocities.
Bill

 

[FrankG]

Interesting that you have a 1-9 twist. The Hornady web site shows an increased BC with a faster twist barrel. I had not noticed that before. Sierra seems to be recommending a faster twist for their new smks. With the larger cases and high velocity many shooters are using a 1-10 in
308 and 1-8 in 6.5mm and getting good results. I have a 1-7.5 on my 6.5 PRC but I used it because there may be future bullets that require it. Also, many shooters are concerned about bullet integrity at high rotation velocities.
Bill

Bill, The Hornady's will fly in a 10 twist. I did a twist calc. on the 230 SMK and I was coming up with a 1-9.24 twist as being min. This is at 2800fps. At 3000fps I'm getting 1-9.548 twist.

I hate running my stuff on the ragged. So I tend to error on the faster side. Even though the 9 twist isn't much faster than the 9.24.

Also as you stated a little faster twist does help the b.c. of the bullet as well.

Another example are the newer 6.5 bullets. The 147 Hornady's will fly in a 1-8 twist at 6.5CM velocities but when I talked to one of the guys at Hornady he liked 1-7.5. We made some test barrels for the 150SMK. The feedback I got was the guns where hammers with the 1-7.5 twist but they we're not seeing the calculated b.c. numbers. So made them a 1-6 twist test barrel and it confirmed everything for them. At 2600fps. I get 1-7.52 as a min. for those. Before I had any of the bullets I had the shop make me a 1-6.75 twist 6.5mm. It is on the gun and chambered in 6.5CM. I'm getting an honest 2700fps out of a 23" barrel. I've shot the 150SMK, 147 ELD-M as handloads and box ammo with 140AMAX's and all have been just hammers. The 150SMK and 147 Hornady's as far as b.c. and actual down range performance I honestly cannot tell a difference. Both are very nice bullets.

Higher twist rates and bullet failures. I don't see this being a problem in larger calibers like .30cal. Even for the most part down to 6.5's I lean towards no even though there are complaints out there on the Sierra's and Hornady's. Not just twist rates but velocity and bullet jacket thickness play a part as well.

The other things you don't hear guys talking about is how many rounds are on the barrel and or damage to the rifling. This will cause bullet failure also. Dave in the shop was at a match just over a month ago. Dave was scoring a guy one day and seen the guy's gun blowing up bullets ( two different guns). The shooter was shooting Hornady's in one gun and Sierra's in another gun. He did nothing but complain about them. Dave started asking questions like how he was cleaning it, round count on the barrels etc....turns out both guns had very high round counts. With out even looking at the barrels Dave told the guy your barrels are done. Get them off the guns!

My .300PRC F open rifle has a 2nd barrel made for it. It's a 6.5 and will be chambered in 6.5PRC and I did it as a 1-7.25 twist. Three other guys in the shop are all building 6.5PRC hunting rifles and we did them all as 1-7.5 twist and they will be shooting box 6.5PRC ammo thru them with the ELD-X hunting bullets.

Later,Frank

 

[wboggs]

Bill, The Hornady's will fly in a 10 twist. I did a twist calc. on the 230 SMK and I was coming up with a 1-9.24 twist as being min. This is at 2800fps. At 3000fps I'm getting 1-9.548 twist.

I hate running my stuff on the ragged. So I tend to error on the faster side. Even though the 9 twist isn't much faster than the 9.24.

Also as you stated a little faster twist does help the b.c. of the bullet as well.

Another example are the newer 6.5 bullets. The 147 Hornady's will fly in a 1-8 twist at 6.5CM velocities but when I talked to one of the guys at Hornady he liked 1-7.5. We made some test barrels for the 150SMK. The feedback I got was the guns where hammers with the 1-7.5 twist but they we're not seeing the calculated b.c. numbers. So made them a 1-6 twist test barrel and it confirmed everything for them. At 2600fps. I get 1-7.52 as a min. for those. Before I had any of the bullets I had the shop make me a 1-6.75 twist 6.5mm. It is on the gun and chambered in 6.5CM. I'm getting an honest 2700fps out of a 23" barrel. I've shot the 150SMK, 147 ELD-M as handloads and box ammo with 140AMAX's and all have been just hammers. The 150SMK and 147 Hornady's as far as b.c. and actual down range performance I honestly cannot tell a difference. Both are very nice bullets.

Higher twist rates and bullet failures. I don't see this being a problem in larger calibers like .30cal. Even for the most part down to 6.5's I lean towards no even though there are complaints out there on the Sierra's and Hornady's. Not just twist rates but velocity and bullet jacket thickness play a part as well.

The other things you don't hear guys talking about is how many rounds are on the barrel and or damage to the rifling. This will cause bullet failure also. Dave in the shop was at a match just over a month ago. Dave seen the guy's gun blowing up bullets. The shooter was shooting Hornady's in one gun and Sierra's in another gun. He did nothing but complain about them. Dave started asking questions like how he was cleaning it, round count on the barrels etc....turns out both guns had very high round counts. With out even looking at the barrels Dave told the guy your barrels are done. Get them off the guns!

My .300PRC F open rifle has a 2nd barrel made for it. It's a 6.5 and will be chambered in 6.5PRC and I did it as a 1-7.25 twist. Three other guys in the shop are all building 6.5PRC hunting rifles and we did them all as 1-7.5 twist and they will be shooting box 6.5PRC ammo thru them with the ELD-X hunting bullets.

Later,Frank

Glad you are gearing up to give the .300 PRC a competitive challenge. That will answer a lot of questions shooters have. I have
always wondered about the 6.5 as a competitive round and maybe your barrel will give some answers. I use mine for fun and have run the 150smks to 3140 with top H1000 loads with no bullet failures.
One lesson from your observations is the the barrel needs to be clean and not worn out. That is not a trivial matter when a new chambered and finished barrel costs a retail customer close to $600.
Keep everyone informed as you and your team accumulates experience with these new PRC rounds.
Bill

 

[Boatschool02]

I'd like to say thank you to Mr. Green.
Even though there is no chance of my building a 6.5 or 300 PRC, I keep coming back to this thread because it is SO refreshing to read well-structured, data driven contributions to this Forum.
I can only imagine all of the interesting tests you've supported or been a part of.
Sunlight is the best disinfectant and we all get better through an increased understanding of what is actually happening, often at the level of test equipment & sample sizes beyond what we will ever see.
I look forward to reading more as your testing continues.
Thanks,
Luke

 

[wboggs]

I'd like to say thank you to Mr. Green.
Even though there is no chance of my building a 6.5 or 300 PRC, I keep coming back to this thread because it is SO refreshing to read well-structured, data driven contributions to this Forum.
I can only imagine all of the interesting tests you've supported or been a part of.
Sunlight is the best disinfectant and we all get better through an increased understanding of what is actually happening, often at the level of test equipment & sample sizes beyond what we will ever see.
I look forward to reading more as your testing continues.
Thanks,
Luke

This is a strong second for your post. We can all learn from his posts. They relate to shooting in general and are not caliber specifc. Frank invests a large amount of time and thought in his posts and it shows.
Thanks
Bill.

 

[venatic]

My 300 PRC will be ready in about 3 weeks... lots of talk on speeds and bullets but nothing on powder. Don’t need charge just what type.
I plan on first starting with 215 Berger and work from there.

 

[N.Shooter]

I see everyone is comparing this 300PRC to 300win and 300wsm but why not the 300RUM? Pardon my ignorance on the subject I am just curious.

 

[Jason_A]

I wonder what the 300 PRC would do with a 180 accubond velocity and COAL wise?

 

[steve123]

I see everyone is comparing this 300PRC to 300win and 300wsm but why not the 300RUM? Pardon my ignorance on the subject I am just curious.

At mag length you don't gain much velocity with 300RUM, the heavy bullets are intruding a lot into the powder column.

In a single shot, or loading long, not wanting to use as repeater, and assuming 300RUM has been throated long for heavy bullets, then 300RUM is getting enough more fps to step ahead of the 300PRC.

 

[B23]

At mag length you don't gain much velocity with 300RUM, the heavy bullets are intruding a lot into the powder column.

In a single shot, or loading long, not wanting to use as repeater, and assuming 300RUM has been throated long for heavy bullets, then 300RUM is getting enough more fps to step ahead of the 300PRC.

I think in off the shelf factory built guns, there is very little difference between just about all of the big .30's, but in custom chambered built guns, as steve123 pointed out, the larger case capacity cartridges like the 300 RUM, will show their extra horsepower and win the velocity race.

The 300PRC seems to nearly mirror the 30 Nosler and it can be argued the 30 Nosler has the better design.

 

[Beeman]

I am sure the 300 PRC will perform. But not enough difference for me to change from my custom 300 Win Mag. It is strictly a hunting gun and shoots the 215's right at 3000 fps. I am sure it is right at max, but shoots great. No pressure signs. Always nice to see new cartridges come out.

 

[Ga6570]

Frank,
Say I wanted to keep the barrel I have but wanted to change the cartridge - Is it possible to have my 300WM rechambered to the 300PRC? From comparison of the saami specs it appears on paper this would work... although my thought is to just shoot out the WM and replace with a PRC when it gets to that point. Lose the belt and gain other perks...

Sam

 

[jamesh]

A lot good information here.

https://www.hornady.com/ammunition/rifle/300-prc-225-gr-eld-match#!/