Irregular velocities with 7prc loads

[hunterbob]

I recently built a lightweight 7prc and started trying to work up a load. I am running into some odd velocities and wanted to see if anyone has experienced anything similar.

I am using ADG brass, h1000 powder federal gold medal match large rifle magnum primers and have tried 175 eld-x and 180 ELD-M bullets velocities are measured on a Garmin zero chrono

During my load work ups I am struggling to find any nodes at all and my velocities jump around a lot there have been 2 charge weights that gave decent which were 66.6grns and 67.5 grns after my initial testing I loaded 5 rounds of 66.6, 66.4 and 66.8 grns, the 66.6 grn group gave me an average velocity of 2815fps with and SD in the teens, 66.4 grns was an average of 2790 with a SD in the 20's and 66.8 had an average of 2754 with an SD in the 20's.

That's just an example and I've been seeing similar results across all charge weights if I load up 5 rounds at least 2 of them are 50-200fps different than the rest and it's had me pretty confused.

The other day I tried a few different primers with a load of 67.5grs and was kinda shocked. I loaded 5 rounds each with gold medal match magnums and Remington lrm primers the federals had an SD of 28 the Remington's had an SD of 9. I also loaded 2 rounds at the same charge with white river standard large rifle primers and the SD from those was 1.6, I know 2 shots is not a significant source of data but still definitely worth exploring more.

So it would seem that my rifle doesn't like the powder/primer combo I've been using and just wanted to see if anyone else has ran into something similar with this cartridge.

Just as a note so far every group I've shot with this rifle has been under 1" at 100yds but I haven't got it out to farther distances yet

I would try doing a factory crimp with the Lee factory crimp tool.
It made a big difference for me with 308 .

 

[Johrichal]

I finally got to shoot some more today. Shot 2 10 round groups of the same charge weights 67.5gr h1000 one with white river LRP and one with Rem. Lrmp the results were better and I think I'm on the right track the Remington magnums primers still didn't shoot great but the white river large rifles were good I'd really like to get my SD's into the single digits but an SD of 11 over ten shots is not bad at all. Groups with the WRLRP opened up a bit to right around 1.5" but I'm sure I can tweak my seating depth and get those down where I want them as well. My next step will be to pretty much start over with the WRLRP and do my standard load work up to see if I can find a good node. Thanks for all the help

 

[Dmagna]

Did you run into pressure signs while working up at all?

 

[Dmagna]

I ran into a lot of issues while starting my 7 prc adventure. ADG brass was showing ejector marks with h1000 at the minimum load. I believe it was because the brass might have had some slop in my chamber and the stopped after 2-3 firing. I use N570 now, so far it's the best powder I can find for the cartridge. I run a 180 Berger hybrid at 3050 with no pressure at all. I have also ran a 195 to 3050 with no pressure. Out of a 26" barrel.

 

[Johrichal]

@Dmagna - I got light ejector marks at around 68gr and stopped there this was after the case had at least 2 firings on them. I am running a 20" barrel with a silencerco 36M suppressor. also my primers seem to have a little cratering to them but it is at all charge weights and not bad so im guessing it's just the rifle

 

[sakoluvr]

I appologize if I missed it, how long is the barrel? Your velocity is pretty low.

I am getting 2975 fps with 180 Scenars over 67.0 H1000 and Fed 215M primers. Hornady brass. I do have a 26" Bartlein.

I have ADG on the shelf that I am going to start over with and find pressure with 180 ELD M's

 

[Koots]

I appologize if I missed it, how long is the barrel? Your velocity is pretty low.

I am getting 2975 fps with 180 Scenars over 67.0 H1000 and Fed 215M primers. Hornady brass. I do have a 26" Bartlein.

I have ADG on the shelf that I am going to start over with and find pressure with 180 ELD M's

Dont be scared that on first firing the adg may show ejector marks even at low charge. As said above ADG that I fired needed that first fire form to fit the chamber and grip well

 

[Dmagna]

@Dmagna - I got light ejector marks at around 68gr and stopped there this was after the case had at least 2 firings on them. I am running a 20" barrel with a silencerco 36M suppressor. also my primers seem to have a little cratering to them but it is at all charge weights and not bad so im guessing it's just the rifle

I think your inconsistent SD and ES is due to inconsistent pressure. Increasing powder might help and level out the load. ADG is sometimes weird, also have had the same issue with alpha

 

[Johrichal]

alright so I finally got my N565 and did a quick ladder to see what kind of velocities I can expect and find max load/pressure signs. I loaded up .5gr increments from 66gr-68gr in once fired ADG brass with sierra 183gr matchkings. Velocity was quite a bit lower than H1000 accuracy was acceptable, and I found no signs of pressure GRT shows the 68gr load as right on the cusp of max pressure and it fills the case all the way to the base of the neck.

I have seen quite a few load suggestions for 180gr bullets with up to 72grs of N565 I am confused as to how anyone got that much to fit in the case at all even with vibrating each case and also it seems like that load would be quite a bit overpressure ill have to go back and check my GRT data again and make sure I dont have anything entered incorrectly.

any of you have any experience with N565 in the 7PRC and ADG brass and if so did you find any pressure signs and at what charge weight did you have to start vibrating cases to pack the powder in?

 

[Mike Matteson]

I had poor results with H1000 in my 22" Proof 7prc, never got velocity I could get with V560 and Grand. Its just too slow for 22" barrel.

You know that H1000 is a slow powder, and in a 22" barrel doesn't seem to me that really works. I would look at H4350 or H4831 powders. They are faster powders, and I would think that would work better in a shorter barrel. I am not a big fan of double based powders either. Do to temp changes with those powders.
I am following just the same. My brother has a 7mm PRC that's he's getting ready to load for and shoot. He loves his 7mm.

 

[Idaho Lefty]

In my sons recently Built, Tikka T-3, 7mm PRC w/ 24" Proof, CF Barrel & Carbon Fiber Stock,.. He Found that,.
F-210M's, 180 Gr. ELD-M's, ADG Brass and around 70 "something" grains of, StaBall HD, performed very Well and is, getting groups from, .314 to, 1/2 MOA, "Repeatedly" with Low, ES / SD's.
He has Yet to, take Rifle Out to, 600 -700 yards to, "Proof" this load Out, Sorry But, It's Extremely,.. Cold / Windy Here, in January.
He hit Pressure and 3,005 FPS at, "around" 72 Grains ( OVER, Max Chg. ! ) of, StaBall HD and "Settled" on LESS Powder and,. 2,987 FPS !
Accuracy is Awesome so Far ! I WON'T Quote the Powder Charge as, he's Probably STILL, a Bit over Max., Per Hogdon's, Reloading Data, ( Knowing My son ! ) as He Loves to, "Stretch, the Limits",.. a Bit !
AS Usual,. "Work Up" loads, Carefully,. IF trying, this Powder ! Good Luck !

 

[Idaho Lefty]

My son will Be using, Factory Hornady 175 gr. ELD -X, ammo for, any CLOSER Range shots, on Elk ( to, 350-400 yds ) and, the Horn M Load he is developing with StaBall H D, will be used for, anything Past that ( to maybe 1,200 yd's, IF, NOT, Windy on, an Elk ) and for, "Plinking Steel" to, 1,500 Yds. The Top Cart in his Tikka Magazine will be the X Bullet and the rest, the M's as Past 400 you "Usually" have Time to, Cycle the Bolt, Twice.
Total Rifle Weight is, 8.7 Pounds, All Up with, the Beautifully clear, 4 x 16, Zeiss Scope

 

[Johrichal]

You know that H1000 is a slow powder, and in a 22" barrel doesn't seem to me that really works. I would look at H4350 or H4831 powders. They are faster powders, and I would think that would work better in a shorter barrel. I am not a big fan of double based powders either. Do to temp changes with those powders.
I am following just the same. My brother has a 7mm PRC that's he's getting ready to load for and shoot. He loves his 7mm.

I was getting fairly good speeds with H1000 in my 20" barrel, I know I had some that were approaching 2900fps with 180 eld m's id have to check my data to give you exact #'s. With N565 the highest ive got is right around 2750 so far

 

[Johrichal]

My son will Be using, Factory Hornady 175 gr. ELD -X, ammo for, any CLOSER Range shots, on Elk ( to, 350-400 yds ) and, the Horn M Load he is developing with StaBall H D, will be used for, anything Past that ( to maybe 1,200 yd's, IF, NOT, Windy on, an Elk ) and for, "Plinking Steel" to, 1,500 Yds. The Top Cart in his Tikka Magazine will be the X Bullet and the rest, the M's as Past 400 you "Usually" have Time to, Cycle the Bolt, Twice.
Total Rifle Weight is, 8.7 Pounds, All Up with, the Beautifully clear, 4 x 16, Zeiss Scope

Ive never used Staball H D how is the temp stability of it?t