My bad. Sorry for the typo. Yes, .240.
7-6.5PRCW load data
- Thread starter Alex Wheeler
- Start date
Alex Wheeler
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There isnt one. It like seating depth or powder charge. This has to be tested.
WallyM
Silver $$ Contributor
I found a slow node (2678) at 51.8 grains and am now testing for 2820 node at 56.7 to 57.6. BTW I'm technically shooting a 7-6.5 PRC experimental built with a custom reamer designed by another member on here, but for most practical purposes it's a PRCW.
One Eye Pete
Gold $$ Contributor
A while back when I couldn’t get 4831sc I picked up some N160 So I need to use it.
My rifle is a Kelby long F-class panda in a Mcmillian kestros Z rail stock with a 31” Krieger 8.5 twist barrel, a B&A two stage trigger and an F-class products tuner. The reamer is a Manson 0.218 neck 0.225 freebore, 1.5 degree throat and 0.535 at the .2 line. I size with an opened up 6.5 PRC Forster bushing die using a 310 bushing followed by a .282 mandrel. Bullets are pointed Berger 180 hybrids ( finally able to get a decent supply of them), brass Lapua, primers CCI BR2. Testing has shown me that the only difference between the CCI BR2s and CCI 34 military primers is the price, group size was the same as long as I sorted them by weigh.
Using N160 and shooting a ladder at 800yds (the max range available to me) I found a node at 55.8 to 56.1 grains. I settled on 56 grains which gives me a velocity of 2890 - 2900 fps.
A seating depth test gave me really nice results between .003 - .009 into the lands. I settled on .008 in which gives me a BTO of 2.457. So far the N160 appears to be fairly easy on the barrel.
I have a 600yd midrange match coming up so on my last outing I did my tuner testing at 600 yds. When I got dialed in I was able to get repeated 4 shot 2 in groups. Now if I can keep the NUT BEHIND THE TRIGGER from coming loose I may do ok at my upcoming match with my new setup.
My rifle is a Kelby long F-class panda in a Mcmillian kestros Z rail stock with a 31” Krieger 8.5 twist barrel, a B&A two stage trigger and an F-class products tuner. The reamer is a Manson 0.218 neck 0.225 freebore, 1.5 degree throat and 0.535 at the .2 line. I size with an opened up 6.5 PRC Forster bushing die using a 310 bushing followed by a .282 mandrel. Bullets are pointed Berger 180 hybrids ( finally able to get a decent supply of them), brass Lapua, primers CCI BR2. Testing has shown me that the only difference between the CCI BR2s and CCI 34 military primers is the price, group size was the same as long as I sorted them by weigh.
Using N160 and shooting a ladder at 800yds (the max range available to me) I found a node at 55.8 to 56.1 grains. I settled on 56 grains which gives me a velocity of 2890 - 2900 fps.
A seating depth test gave me really nice results between .003 - .009 into the lands. I settled on .008 in which gives me a BTO of 2.457. So far the N160 appears to be fairly easy on the barrel.
I have a 600yd midrange match coming up so on my last outing I did my tuner testing at 600 yds. When I got dialed in I was able to get repeated 4 shot 2 in groups. Now if I can keep the NUT BEHIND THE TRIGGER from coming loose I may do ok at my upcoming match with my new setup.
I got my ES into the single digits with H4350 in a node centered at 53.1 gr. I ran out of ammo before I could get a seating depth. I have enough feedback to believe I am going to find the sweet spot somewhere in jam. I could not get a good ES with any charge of H4831sc between 56.5 and 58.5gr though it seemed to be settling down the higher I went. I didn’t feel comfortable going higher than 58.5. 58.5 of H4831sc was giving me 2920 fps. 53.1 gr H4350 was giving me 2860.
Got to the range using N555/210M/175gr Berger Elite Hunter, once fired full length resized Lapua brass using .311” bushing, CBTO-2.306” elev 800’, temp 40 deg, I loaded in .3gr increments up to 59.1, my Garmin chronograph decided halfway through testing it needed to update so I called it a day and will finish next time out, stopped at 57.3grs which looked ok,
I was very happy with the consistency in velocity from 57.0/57.3 loads
25 inch 1-8 twist Benchmark CF wrapped barrel
I was very happy with the consistency in velocity from 57.0/57.3 loads
25 inch 1-8 twist Benchmark CF wrapped barrel
Well the 32" pressure test barrel got finished yesterday. Shipping out to Hornady today. I took it home to last night just to double check seating depth on all the bullets.
I should have the ammo all loaded up not next week but week after and get that shipped down to them as well.
Then it's whenever Hornady can schedule it in for doing the testing.
I should have the ammo all loaded up not next week but week after and get that shipped down to them as well.
Then it's whenever Hornady can schedule it in for doing the testing.
no yes no and maybe not! LOL!
Yes the barrel in the pictures is brand new.
Not every barrel speeds up. A lot of that has to do with how your cleaning it, number of rounds fired in between cleanings and type of powder being used etc... there are a lot of variables. They will record all pressure and velocity data from the first round fired. All ammunition makers do that. Some ammunition makers will not use a test barrel for actual ammo production testing until it has 100 rounds on it. This can also be caliber specific. If the barrel is going to change pressure/speed up it will typically do it in 100 rounds or less. Magnum calibers typically change much sooner then say a 308win or 223 Rem. type caliber. If there is any changes they will see it regardless. I'll probably load 60 rounds with 180ELDM bullets for barrel break in if you want to call it that. Typically the will shoot a few rounds thru the barrel and clean it an see how it cleans etc... then they will fire say 20-40 rounds thru the barrel going easy on it and then clean it again. Then they go into they're normal testing procedure/cycle. I know depending on ammo maker and using 308w as an example they might shoot anywhere from 50 to a 150 rounds thru the barrel in between cleanings. I'll say 50 is more of a standard. All accuracy is from 10 shot groups and typically at 200 yards. So when I load the ammo with a given bullet and powder charge.... it will be a minimum of 20 rounds and in some cases more. Depends on the bullet and the load. The bullets I'm going to lean heavy on are the 183smk and 180 Berger's. Then the 166 and 190 Atips.
Case capacity doesn't get measured. I can do a measurement but not necessary. I offered Hornady when I said I would load all the ammo and I would supply all the lot numbers for the powders, bullets and primers and I would supply brand new cases.
Hornady said that they would supply the cases because! This way when I get the cases I have to record the lot number of the brass so it's included in the load information. They would have already run those cases in pressure test barrels and have that number recorded (for calibration purposes) for that particular lot of brass. This number has to be included in the data so the brass doesn't skew any of the pressure data. Your trying to eliminate as many variables as possible so your data is good. Brass varies. Just like the jacket material from lot to lot can vary.
So all the loads will be with virgin brass. Not once fired etc... yes typically once fired brass because after the first firing will still fire form/blow out any internal imperfections and at times your s.d's will drop a little on the once fired case vs virgin brass.
In the end this will give us real world data.
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Doesn't really matter.
I originally wanted a 8 twist barrel but when it got put into the rifler the previous barrel was a 8.25 for a customer and he didn't see the change so ran it as a 8.25 twist. That's the reason we ended up with a 8.25 twist barrel. Shop asked me if they wanted me to make a new one. I said no... as it won't make a hill of beans difference.
The twist will have no bearing on pressures or velocities. That's why it really doesn't matter.
Some 197SMK bullets will be shot thru the barrel.... yes they need like a 7.5 twist minimum. In this case I'm not worried about the accuracy on those bullets as the main concern again is pressure and velocities but we can shoot the 197's to get a baseline for a max load for those regardless of the group size.
The 190ATIPs according to my numbers roughly need a 8.23 or a 8.26 twist to stabilize ( I forget which ) those.... so those will be right on the edge for stabilization but for shooting at 200 yards in controlled conditions it shouldn't have any real negative effect on the accuracy.
Typically a p&v test barrel the accuracy is a little less than a straight up accuracy test barrel but then again an accuracy test barrel won't give you pressure readings.
As a close rule of thumb... I'll say a pressure test barrel accuracy wise will shoot about the same to say maybe a .1xx" to .2xx" larger groups vs a straight up accuracy barrel.
That's why ammo makers are always ordering both pressure and accuracy test barrels when testing ammo.
A straight up accuracy test barrel you/they can chase the lands/throat and play with seating depths when testing strictly just for accuracy per se just on bullets but when a ammo maker has to load for two specs... pressure and velocity when making a run of box spec ammo... they are not allowed to chase it per se. Once they see a pressure spike and typically a velocity loss that's a warning sign the barrel is on it's last legs for pressure and velocity testing and will get pulled from service.
I'll say most guys are running a 8.5 twist barrel. Then I'll say the next most popular is 8.75 and then a 8.25 or 8 twist barrel. Some guys are still shooting 9 twist barrels but not as much as the others.
I did shoot the 183smk when they first came out thru my 9 twist barrel 284win and they shot every bit as good as anything else. No load tuning etc... ran the same load as the 180VLD's and first time out in 21 degree temperature they shot .4" or better for four five shot groups. I'll tell you though they should be shot thru something faster than a 9 twist. You would be lucky if those bullets shot out of a 9 twist button barrel. The cut rifled barrels guys seem to be o.k.
My 7/6.5PRC barrel.... I did it as a 8 twist.
So H4350 is where I’m landing. Didn’t try N555 because I have a lot of H4350. 53.0 gr 2880 fps. ES 9-10 fps across three 20 shot strings. Still tinkering with seating depth. Both .015 jump and .015 jam give me between .19 and .3 inch groups at 100 in much less than ideal conditions. Very gusty tail wind. Need to refine seating depth more with some decent conditions. Trying to get under .25 groups before moving out to distance. 152 rounds down the barrel so far.
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