To me, the dimensions of the Blackhorn QRBP are better suited to using rifle primers, not shotgun primers. A couple of days ago a rifle, and a couple of breech plugs came in the mail, so yesterday morning the flash hole of the Blackhorn plug was enlarged to 0.035". A dutchman and some red loctite were put into the mortice . The dutchman was made by cutting a small piece off the QRBP fitment tool. Using JB Weld to fill the mortice was considered, but in the end, the dutchman was used instead.

This morning the loctite had hardened, so the plug was turned in a lathe till the dutchman was flush. Then the primer socket was enlarged in a mill, so the Precision Rifle large rifle primer adapters could be used. The socket was also made deep enough so that an o-ring would fit, and allow the rifle to go into battery, and the hammer be cocked.









The shooting set today, was just about the same as yesterday, except the truck was parked one foot further away, and it was 4 degree, instead of 6 degree. Five shots were taken at 85 yard plus 1 foot. The scope setting was the same as yesterday' final setting.








The Blackhorn QRBP didn't fit the barrel as nicely as the QRBP used yesterday, so there was some blow by, but ignition was perfect. Finishing the plug was more difficult than i envisioned, so now i am wishing i would have used JB Weld to fill the mortice..

Only had 4 vials of powder left. Pressing the 5/8" bolt into the breech plug, and redoing the marriage of the plug to the barrel, did help. The fit isn't perfect, but far less soot got past the rim of the breech plug. As expected there is no change to the leakage at the primer end. Perhaps adding a 0.005" shim or so, behind the firing pin bushing will cure the leak, maybe..

















Wow, the point of impact sure changed this morning. Temperature was a way warmer, 36 degree, is that why? In order to fit the plug to the barrel using a little pipe wrench, i had to remove the fore end, and barrel from the breech, is that why? Seems the removal and replacement could have changed the impact. The screw holding the fore end seemed kinda loose when i removed it, and i am sure it is tighter now than it was.

I think your poi changed due to tighter seal on breech plug to barrel. Just my opinion.

Interesting thought. I doubt the temp change could make that kind of shift.

Maybe its just auto-adjusting closer to where he'd want it sighted in anyhow.


Hey Ron, how come you filled in the tool slot? Just curious.

Because i was nervous about how thin the remaining steel was going to be at the juncture between the primer socket and the tool slot, (see photo) when the primer socket was enlarged to use the PRbullet adapters. The tool slot is only needed to be used once, to marry the plug to the barrel, then it is never used again. However, this plug didn't fit the barrel so very good, so i could have used the tool slot once more. Instead had to use a pipe wrench, after using Busta' suggestion to use the chamfer on the end of a 5/8" bolt to open up the rim on the end of the plug.

I think grouse is wright your getting a better seal so your getting more psi to the bullet and not linking back .
and it looks like its steel linking some but better.

You certainly could be correct it seems.

My inclination was to attribute the impact change to the difference in tension of the fore arm screw being tighter today.

There were two other changes i forgot to mention. One is i changed how i was holding the rifle, so i could hold it tighter to my shoulder. The other is i used a different ram rod, with a spin jag today, but the first two days the ram rod didn't have a spin jag, it was supposed to spin in the handle, and it didn't seem like it was.

Yep, i did a poor job of controlling the variables.

All you can do is seat the breach plug the same way every time and have the rod in the gun you will be hunting with and shoot it a few different times and see if it maintains consistency.

The other problem could be the rifle primers. I personally would never use them with any powder. The standard rifle primers are just not hot enough for me. I would suggest using the magnums but I still would not use them myself. I want as much heat/fire directed to the powder as I can. And with the more flame I firmly believe you will have a more consistent ignition in all applications. Especially in hunting conditions including rain, snow and cold temps.

The forearm was removed again yesterday, and the head space adjusted a tad. Then the fore arm screw was tightened the same as it was the day before to 40 in-lbs. The first shots this morning, hit just about exactly where the shots hit yesterday. My belief is the loose fore arm screw had the rifle shooting to a different point of impact. Probably i should have checked the screw before i ever shot the rifle, but i didn't.

When one installs the QRBP, one just turns it in with fingers, until it stops. When the shooting is done, one just unscrews the plug with one's fingers.

These magnum rifle primers have been tested in sub-zero temperatures in more than one rifle, and ignition seems perfect. One Omega was left loaded, in the truck, for near exactly a month, and one sub-zero morning it fired without hesitation. Myself, i am not inclined to switch back to using shotgun primers. The one Omega plug modified to use rifle primers, i used in 4 different rifles, and results were always good. That plug has about 800 shots through it, if my memory is correct. The flash hole has never never eroded larger. From time to time i have used the rough part of the torch tip cleaner vigorously to remove carbon from the flash hole. This is something i would never ever do when using shotgun primers. Today, after 10 shots, the carbon in the flame channel of the QRBP, was removed by spinning a bare 1/8" drill in my finger tips. No way can one do that when using shotgun primers.

Time will tell, but at this time it seems what i need to do to have the rifle shooting consistent, to the same point of impact, is tighten the fore arm screw to the same in-lbs, each time.

This rifle will never get to go hunting anyway.

You could be right about the forarm because Knight bolt guns act the same way when the stock screw is loose.