Frank are ya'll going to pressure test for normal barrel lengths,
like 24/26 or just go with 28/30/32 since that what guys are using in the field r/n?
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7-6.5 PRC
- Thread starter Jackomason
- Start date
like 24/26 or just go with 28/30/32 since that what guys are using in the field r/n?
When the 7 PRC was a still a fetus (2018-2019 timeframe), Seth Swerczek had done a 7-6.5 PRC that he briefly used for hunting. I believe it was lovingly called the "7 doucher".
But yes, as far as real load data and serious testing, we haven't really done anything up 'til now with it.
Right now it’s just the 32” finish length. When the initial round of testing is done. The barrel will remain at Hornady. They can do with it what they will. My hope is that sometime… they will do more load development and put that data out there.
It would also be up to them if they like… they could cut the barrel down finish length wise to say 24” and run more tests etc…right now though again… 32” is where it starts.
Yes I did talk to Seth…. And I wasn’t even going to go there!When the 7 PRC was a still a fetus (2018-2019 timeframe), Seth Swerczek had done a 7-6.5 PRC that he briefly used for hunting. I believe it was lovingly called the "7 doucher".
I look forward to you guys doing this and getting some hard baseline data.
All of the ammo is shipping out today for pressure testing. Hopefully they can schedule the test in as quickly as they can time permitting.
There are loads with N555 powder, H4831sc and H4350. Bullets are 166 and 190 Atips, 180 Berger Hybrids, 183 and 197SMK and 180 ELDM's.
260 rounds in total for this round of testing.
Later, Frank
Bartlein Barrels
There are loads with N555 powder, H4831sc and H4350. Bullets are 166 and 190 Atips, 180 Berger Hybrids, 183 and 197SMK and 180 ELDM's.
260 rounds in total for this round of testing.
Later, Frank
Bartlein Barrels
What advantage does the 162 have over the berger 156? It's a few grains heavier but the 6.5 156 has a better BC.
I don't understand why a medium or long action makes a difference in this case. The 156 is longer than the 162, I understand that either one would need to be shortened to less than maximum length to fit in a SA mag. But if I'm going to expand a 6.5 PRC case to 7mm I would be looking to run a bullet in the 180 grain range in a medium action. I'd rather shoot the 156 over the 162 ELDM no matter what action I was using.
you are giving up a lot of case capacity running the 156 at short action mag length. The 162 being a bit shorter and generally running at a fast speed out of a .284 barrel compared to a 156 out of a .264 at similar pressures. Running a 6.5 PRC out of a long action can really wake it up.
I have to agree with what he is saying.
I go back to the 284win. It was originally designed to run thru a SA type gun but with heavier/longer bullets your stuffing them so far into the case your sucking up case capacity which in turn will make velocity suffer. If your going to seat heavier/longer bullets to use the case capacity you need to run the round thru a longer magazine box length / long action. Or like in F Class where the guns are primarily single shots so you don’t have this issue.
I feel the same way about the 6.5PRC and the 7/6.5PRC or similar type rounds. I feel they are better suited for a long action type gun or if you will a short action but a short action that has a slightly longer magazine box where the rounds can have the bullets seated out further. Kind of like the Defiance XM action which can handle up to a 3.250” length round vs a short action where typically the magazine length only can handle a 2.8” round or a smidge longer.
That's why my 6.5 PRC is on a tikka action. Just didn't see the point in the 7mm 162 over the 156 that works without having to expand the brass to 7mm for what I think isn't a better bullet. If you're going 7mm, I'm going to load 180's.
I’ve sold several rifles, to build one rifle with multiple barrels. To me it makes more sense than building several rifles at twice the cost. In my case it’s a 25 Creedmoor on a 737R that I plan on using for NRL Hunter. I’m trying to find the best hunting caliber that will fit in a short action. Looking at 7 SAUM, 7 Sherman Short, or 7-6.5 PRCW. I have a pile of 168 VLD’s that need used up. Everyone can talk about how great the 180’s are, and I agree they are, but 168 VLD’s have killed a lot of game and seem to fit best on a short action.
I just found this thread and very much appreciate Mr. Green working to get some pressure data
Short Answer: The 284 Winchester is a 56K psi cartridge (the 6.5-284 is 58K psi) and some shooters routinely push it above 65K where brass life is not good. The 6.5 PRC starts off as a 65k psi cartridge, so the brass is made to handle higher pressure.
For what it's worth, in a Hornady podcast, it was mentioned that several common competition 6.5-284 loads were pressure tested at above 65K psi. The 284 competition loads are likely not lower.
Longer Answer: By the early 1960's, Winchester wanted to compete against the Remington's Models 740 (semi-auto) and 760 (pump action) rifles which could chamber the 280 Rem, Remington's answer to the 270. Winchester responded with the Model 100 semi-auto and Model 88 lever-action rifles in 284 Win. Those rifles were originally designed around the shorter 308 Win cartridge. As is typical with those types of actions, the bolt strength is the weak link and they were designed to handle the loads of the 308. To get 270 or 280-like performance, Winchester got clever and developed the 284, which had a fatter case than the other two (0.500"vs 0.470" dia). They then rebated the rim to match the 308-sized case head. Bolt strength then became an issue. The backthrust against a bolt is related to max case (internal) cross-section area multiplied by the max chamber pressure. To match the bolt thrust of the more narrow 308 at 62Kpsi, the SAAMI Max Average Pressure for the 284 was limited to only 56,000psi. The later Norma 6.5-284 is only slightly higher at 58K psi.
Yes, it would be possible to make 284 brass that could handle higher pressures, but that would involve thickening web and the walls near the base. This would reduce case volume and velocity for those who don't need the extra strength. The 6.5 Grendel and 6mm ARC are in a similar predicament, BTW. The brass was thinned out to provide max powder capacity at the relatively low 52K psi needed to avoid bolt problems with AR15's. This, however has prevented its use at higher pressures in semi-autos with stronger bolts (bolt-actions with chambers that offer more support near the case head can go a bit higher, though).
For those who really want to stay with a 284 derivative and run higher pressures, there is a potential solution. The relatively new 6.5 and 338 Weatherby RPM cartridges use a longer variant of the 284 case that is beefed up to handle 65k psi. It would take cutting this brass down, forming and neck trimming, but the case life should be better. The propellant volume will be lower, though.
The question of "Why not the 284?" has come up several times in this thread. On one of his YouTube videos, Erik Cortina said that his 284 ( a Shehane, IIRC) was just as accurate as his 7PRCW. In fact, he said he carried the 284 to South Africa for a competition as a backup rifle. According to a couple of comments in videos, Cortina said that he switched to the "magnum cartridge", 7-6.5 PRCW to get better brass life. The history of the 284 Winchester is largely to blame for for this.
Short Answer: The 284 Winchester is a 56K psi cartridge (the 6.5-284 is 58K psi) and some shooters routinely push it above 65K where brass life is not good. The 6.5 PRC starts off as a 65k psi cartridge, so the brass is made to handle higher pressure.
For what it's worth, in a Hornady podcast, it was mentioned that several common competition 6.5-284 loads were pressure tested at above 65K psi. The 284 competition loads are likely not lower.
Longer Answer: By the early 1960's, Winchester wanted to compete against the Remington's Models 740 (semi-auto) and 760 (pump action) rifles which could chamber the 280 Rem, Remington's answer to the 270. Winchester responded with the Model 100 semi-auto and Model 88 lever-action rifles in 284 Win. Those rifles were originally designed around the shorter 308 Win cartridge. As is typical with those types of actions, the bolt strength is the weak link and they were designed to handle the loads of the 308. To get 270 or 280-like performance, Winchester got clever and developed the 284, which had a fatter case than the other two (0.500"vs 0.470" dia). They then rebated the rim to match the 308-sized case head. Bolt strength then became an issue. The backthrust against a bolt is related to max case (internal) cross-section area multiplied by the max chamber pressure. To match the bolt thrust of the more narrow 308 at 62Kpsi, the SAAMI Max Average Pressure for the 284 was limited to only 56,000psi. The later Norma 6.5-284 is only slightly higher at 58K psi.
Yes, it would be possible to make 284 brass that could handle higher pressures, but that would involve thickening web and the walls near the base. This would reduce case volume and velocity for those who don't need the extra strength. The 6.5 Grendel and 6mm ARC are in a similar predicament, BTW. The brass was thinned out to provide max powder capacity at the relatively low 52K psi needed to avoid bolt problems with AR15's. This, however has prevented its use at higher pressures in semi-autos with stronger bolts (bolt-actions with chambers that offer more support near the case head can go a bit higher, though).
For those who really want to stay with a 284 derivative and run higher pressures, there is a potential solution. The relatively new 6.5 and 338 Weatherby RPM cartridges use a longer variant of the 284 case that is beefed up to handle 65k psi. It would take cutting this brass down, forming and neck trimming, but the case life should be better. The propellant volume will be lower, though.
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I think a lot of this is driven by people are looking for the perfect short action magnum cartridge. The more time goes on it's looking like that is a fools errand.
With a bit of luck the XM action length will take of in popularity and if not become the new normal atleast become popular.
My dream rifle would be a switch barrel mid length action and be able to run 223, 6.5CM and 7mm magnum of some sort on the one rifle.
But....but.....but... then it wouldn't be a Short Action Rifle <GASP!> 
These already exists, they're called Tikka with a switchlug and different bolt stops
Just kidding, I was actually looking for a proper XM length Rem style action couple of years ago as a do it all switch barrel but the lack of magazines and stock/chassis options stopped me.
I did think about just doing it on a Tikka but you are limited in mag capacity and my thoughts are more comp rifle than hunting.These already exists, they're called Tikka with a switchlug and different bolt stops
Just kidding, I was actually looking for a proper XM length Rem style action couple of years ago as a do it all switch barrel but the lack of magazines and stock/chassis options stopped me.
There are a few places doing Tikka XM bottom metals and you can get XM mags in 308 and short mag, but nothing is 223.
Not sure why 223 is always such an issue. There are plenty of people running 80+gr bullets and have been for years, not sure why we are still stuck with 2.55" coal magazines.
I agree we need much better 223 mags especially for long coal. That’s why I went with 75 eldm and 80.5 Berger rather than 85/88 in my last 223 build because I didn’t want to modify mags.
I want to live long enough to see a AW style double stack double feed 20 rounds 223 mags with an adjustable latch
Im getting a 223AI done on a Tikka action and want to use CTR magazines that are too expensive to risk modifying.
Im going to try run 88s but may have to settle on 75/80s.
Until AI come out with a 223 I don't see 223 AW mags ever being a thing.
No reason the aftermarket couldn't do it but 223 never seems to get much love.
Everytime I think about doing the "ultimate multi cal" build I end up deciding it's not worth it/not practical yet.
Maybe the new XM action AI AT-XMC with changeable bolt faces is just around the corner....
So to bring you all up to date. Testing is underway at Hornady on the P&V test barrel we made and the ammo we supplied.
All of the ammo loaded with N555 powder was shot this past Friday. They should be done with all the testing by the end of the week.
Again I have to give a shout out to Hornady for running the test! Thanks guys!
Attached is a pic of the test barrel in the fixture.
Later, Frank
All of the ammo loaded with N555 powder was shot this past Friday. They should be done with all the testing by the end of the week.
Again I have to give a shout out to Hornady for running the test! Thanks guys!
Attached is a pic of the test barrel in the fixture.
Later, Frank
Attachments
I don’t think so. I did ask if it was a possibility for the 7/6.5PRC would be come Saami? I was told no. That was late last year. Unless it keeps getting pushed by market demand than maybe???? ADG is now making factory brass for the round.Frank, does this mean we will see 6.5 PRC, 7-6.5 PRC, 7 PRC, 30-7 PRC and 300 PRC all factory loaded from Honady?? I will give it to Honady as “The King” of marketing
30-7PRC… not even on the radar.
I did a few years ago ask about the 7-300PRC. This was prior to the 7PRC coming out and I was told no. Wouldn’t be nothing but a problem child is what I got out of it. Way over case capacity the 7-300PRC. Even the 7PRC is getting on verge of over case capacity. There is another new 7mm coming out. Not by Hornady. Again over case capacity. Burning up barrels in 550-750 rounds.
Some of this is getting out of hand.
Won’t happen. I asked a while back. Would be nothing but a problem child is the way I got it.
Those 500-700 round cartridges keep you guys in business. I’m going to try a witches brew on a 33xc barrel later this year. Stay tunedI don’t think so. I did ask if it was a possibility for the 7/6.5PRC would be come Saami? I was told no. That was late last year. Unless it keeps getting pushed by market demand than maybe???? ADG is now making factory brass for the round.
30-7PRC… not even on the radar.
I did a few years ago ask about the 7-300PRC. This was prior to the 7PRC coming out and I was told no. Wouldn’t be nothing but a problem child is what I got out of it. Way over case capacity the 7-300PRC. Even the 7PRC is getting on verge of over case capacity. There is another new 7mm coming out. Not by Hornady. Again over case capacity. Burning up barrels in 550-750 rounds.
Some of this is getting out of hand.
Big guns need cleaning. I have found this outYep they do but they bring other problems…. “My barrel only went 385 rounds! Did you ever clean it? No! Not my problem!
With the 7prc and 28 nosler out there.. my brain only goes to weatherby who might just have enough faithful fudds who think a 7-300 weatherby is a cool idea.
7mm RPM maybe?
7MM STW vs 28 Nosler
I have rifles in most popular calibers 25, to 338 calibers but I don`t own any 7 mm calibers at all. Going to get a new rifle built thinking about the 7MM STW or 28 Nosler. Which would you all prefer & why?
So it should go without saying but I will say it anyways. Lot of powder variances, bullet lot variances from lot to lot and not to mention bullet diameters, primers, brass lot etc... all can change the pressure and velocities. Be careful with what you do! Don't forget.... temperature, humidity, pressure, altitude etc... can have an affect as well. This test was run in a lab in controlled conditions.
Not to mention that differences in chamber reamer spec's of what we used for the test/in our guns here and the pressure test barrel vs what you might have in your gun and as well as what your barrel measures for bore and groove dimensions vs what our test barrel was made to can make a difference as well.
Again I have to give a big thanks to Hornady and Joe and Jayden there for supplying the brass, bullets (166 and 190 ATIPS) and running the test! Thanks to Tommy at Sierra for supplying the 183SMK and 197SMK bullets for the test. Thanks to Ken at Capstone for supplying the Berger 180 Hybrids and the N555 powder used in the testing. The guys here at Bartlein for making the barrel and for Scotty here doing the chamber work and pressure port work etc.. in finishing the test barrel.
Max working pressure for the round is 65,000psi.
Twist does not effect pressure.
All pressure and velocity data is for 10 rounds fired for each load.
The p&v barrel measured 32" finish length.
Twist = 1-8.25
5R rifling
Bore size = .2773"
Groove size = .2843"
Headspace = go +.0002"
All of the ammo listed below has N555 powder. All ammo loaded with CCI#200 Primers. All brass was Hornady brass. All primer flash holes where checked for and or deburred.
All bullets where seated .020" off the lands of a brand new chamber. This was not a bullet test for accuracy. So no bullets/ammo had the bullets seated closer to the lands or further off the lands. No load tuning was done in anyway shape or form. In making this statement no bullet clearly out performed one over the other. All bullets shot very good. Noticed I listed the o.a.l. of my loaded rounds and not the base to ogive dimension. Some of my o.a.l. data I left at home. Let me update that information later today.
So for the 180gr class bullets.... I will say as you approach the 57.0gr powder charge... approach it with caution as you are going to be hitting that 65psi limit even possibly before depending on all the variables. There where no flat primer signs, hard extraction etc... At the top I put in bold letters... average pressure that's because that's the average. There are rounds fired with in a group that could be over the number listed for velocity and pressure was even slightly higher... so these numbers are an average. A good example is the 55.0 load for the 190ATIP. The average is 64829 but there where 3 rounds that went just past the 65k limit.
I'm still reviewing numbers and data and with more data to come for H4831sc, RL16 and H1000 powders. So check this post from time to time as I will be making updates as more information comes in and I'll try and keep my original post #1 going as I get more info.
I was having trouble with the layout on the post. So I saved it as a pdf. You have to click on the attachment. I'll clean it up more later.
Later, Frank
Bartlein Barrels
P.S. it should go without saying but I will say this... "Guys keep your comments civil and think before you type!" Everyone involved with getting this testing done did not receive any $ compensation in anyway shape or form. Everyone did this as a request/thought from me and we all did it to help the shooting community using this round and that there is no baseline/data for to go off of. I don't even want to know how much time and set up it took Hornady to run the test and compile the data and the cost involved with that.
Not to mention that differences in chamber reamer spec's of what we used for the test/in our guns here and the pressure test barrel vs what you might have in your gun and as well as what your barrel measures for bore and groove dimensions vs what our test barrel was made to can make a difference as well.
Again I have to give a big thanks to Hornady and Joe and Jayden there for supplying the brass, bullets (166 and 190 ATIPS) and running the test! Thanks to Tommy at Sierra for supplying the 183SMK and 197SMK bullets for the test. Thanks to Ken at Capstone for supplying the Berger 180 Hybrids and the N555 powder used in the testing. The guys here at Bartlein for making the barrel and for Scotty here doing the chamber work and pressure port work etc.. in finishing the test barrel.
Max working pressure for the round is 65,000psi.
Twist does not effect pressure.
All pressure and velocity data is for 10 rounds fired for each load.
The p&v barrel measured 32" finish length.
Twist = 1-8.25
5R rifling
Bore size = .2773"
Groove size = .2843"
Headspace = go +.0002"
All of the ammo listed below has N555 powder. All ammo loaded with CCI#200 Primers. All brass was Hornady brass. All primer flash holes where checked for and or deburred.
All bullets where seated .020" off the lands of a brand new chamber. This was not a bullet test for accuracy. So no bullets/ammo had the bullets seated closer to the lands or further off the lands. No load tuning was done in anyway shape or form. In making this statement no bullet clearly out performed one over the other. All bullets shot very good. Noticed I listed the o.a.l. of my loaded rounds and not the base to ogive dimension. Some of my o.a.l. data I left at home. Let me update that information later today.
So for the 180gr class bullets.... I will say as you approach the 57.0gr powder charge... approach it with caution as you are going to be hitting that 65psi limit even possibly before depending on all the variables. There where no flat primer signs, hard extraction etc... At the top I put in bold letters... average pressure that's because that's the average. There are rounds fired with in a group that could be over the number listed for velocity and pressure was even slightly higher... so these numbers are an average. A good example is the 55.0 load for the 190ATIP. The average is 64829 but there where 3 rounds that went just past the 65k limit.
I'm still reviewing numbers and data and with more data to come for H4831sc, RL16 and H1000 powders. So check this post from time to time as I will be making updates as more information comes in and I'll try and keep my original post #1 going as I get more info.
I was having trouble with the layout on the post. So I saved it as a pdf. You have to click on the attachment. I'll clean it up more later.
Later, Frank
Bartlein Barrels
P.S. it should go without saying but I will say this... "Guys keep your comments civil and think before you type!" Everyone involved with getting this testing done did not receive any $ compensation in anyway shape or form. Everyone did this as a request/thought from me and we all did it to help the shooting community using this round and that there is no baseline/data for to go off of. I don't even want to know how much time and set up it took Hornady to run the test and compile the data and the cost involved with that.
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My post with the data was updated. I listed the powder and also updated the OAL of the round with each bullet.
excuse my ignorance, how does one extrapolate velocities from a 32" barrel to lengths someone would more commonly have in a field rifle?
26-18" using 25 FPS per inch is close enough to ballpark usually - how does that work from 26" to 32"? A little less gain per inch? 120 fps'ish difference between 26" and 32"?
26-18" using 25 FPS per inch is close enough to ballpark usually - how does that work from 26" to 32"? A little less gain per inch? 120 fps'ish difference between 26" and 32"?
Does anyone know how these loads compare to those being used by competitors? IIRC, the main reason for the switch from 284-based cartridges was poor case life. I suspect that competitors worry less about holding 65,000 psi and more about accuracy with acceptable case life.
The 284 is rebated rim, so the case head is smaller in area.This equals more bolt thrust at fixed chamber pressure. moving to magnum boltface you get less bolt thrust, with equal chamber pressure. In theory, this implies a chance greater brass life.
Going from a 32" barrel down to a 26" barrel I say your going to cough up about a 150fps.
A good rule of thumb is 25fps per inch loss or gain but it really depends on caliber (bore size) and what the barrel is chambered in etc...
After 28" for example a 6BR only gains about 8fps per inch.
Accuracy is just as good with this round vs the 284win.
Guys pushing the 284win at 2850fps and faster.... brass life is shorter and at those velocities in a 284win because I'll guarantee the pressure is higher.
That's the biggest thing will see with the 7/6.5PRC is you can push the 2900fps + envelope at normal max pressures and the case life will be better.
that's a loaded question. People shoot NF ELR with 6.5CM, 25SAUM and obviously much bigger
what do you define as 'max accurate range' ignoring the shooter
True. What I mean by that is the point at which you'd be better switching to another cartridge. Hard to define but I imagine much past transonic range it's going to be harder to reliably hit targets. Personally I'd want to be hitting 1MOA targets.
What bullets are you shooting? What's the gun for?
Max accurate range is pretty open ended. That's going to come down to the individuals shooting skills along with reading the wind and the guns capability etc... and don't forget the environmental conditions of temperature, humidity etc...
I'd also be using 5R rifling to help minimize any negative effects from conventional rifling and effecting the BC of the bullet.
If I just look at bullets and velocity... The 190ATIP's if you can push them 2900fps... just on pure calculations they are just above the speed of sound at 2k yards. So in theory that would be the max range to shoot accurately.
Just a couple of weeks ago Scott from AI tied for 1st place. He was shooting a 7/6.5PRC with the 190ATIPs. He had to go into a shoot off I think the shoot off distance was a 1k yards but someone can correct me if I'm wrong and the max distance at the match was 2200 yards? I think Mitch and him were tied. Mitch was shooting a 300 Norma with a big Berger bullet? 230 or 245? Don't quote me on that. Mitch won the shoot off. Gotta give Scott credit as I think that was the only match he shot this year. Even a big heavy 30cal bullet like that your pretty much max'd at the same distance to keep the bullet above the speed of sound.
Either way both of those guys shot great but I feel that Scott wasn't leaving anything on the table against the 30cal with the 7mm.
Scott's bullets where coming out at 2840fps. and a load similar to his was doing 2875fps out of the 32" test barrel. Scott's barrel is a 30" finish length. I'm still waiting on more load test data.
My .02.
Later, Frank
Thanks Frank. That's just what I was hoping to hear. Sounds like a great option for any kind of range I'm likely to shoot. Impressive performance against much bigger cartridges.
Again at this time no plans for doing testing in a shorter barrel length. F class is pretty much running 30" and 32" barrels. That's why we did 32".
Unless for some reason more testing by a ammo/bullet maker wants to be done and in a Saami spec. type finish length of 24" (the most common) or if and this is a big if.... if the round would be submitted to Saami would be the only reasons.
or possibly as the barrel will stay at Hornady if they want after this testing is done... they can cut it down to 24" and use it at will until it's junk. That's cool with me.
One of the reasons Hornady agreed to do the testing was to help the shooting community like we are doing and also I would think for similar cartridges it adds more data.
We've asked them for favors/help at times and vice versa. It is cool having other manufacturers willing to help. Again, it was nice having all the places involved supply and do things and did it at n/c so that's why I have to Thank Hornady, Sierra, Capstone in helping getting this pulled off.
Unless for some reason more testing by a ammo/bullet maker wants to be done and in a Saami spec. type finish length of 24" (the most common) or if and this is a big if.... if the round would be submitted to Saami would be the only reasons.
or possibly as the barrel will stay at Hornady if they want after this testing is done... they can cut it down to 24" and use it at will until it's junk. That's cool with me.
One of the reasons Hornady agreed to do the testing was to help the shooting community like we are doing and also I would think for similar cartridges it adds more data.
We've asked them for favors/help at times and vice versa. It is cool having other manufacturers willing to help. Again, it was nice having all the places involved supply and do things and did it at n/c so that's why I have to Thank Hornady, Sierra, Capstone in helping getting this pulled off.
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