Flash Hole uniforming

[birdiemc]

Finally got around to taking some pictures. First two are Winchester brass, before and after using a Lyman flash hole uniformer. 3rd picture is untouched Nosler brass. I think I'm liking the results with your uniformer better.

View attachment 173296View attachment 173297View attachment 173298

Wow that winchester is pretty gnarly looking to start with.

 

[Savage 12BVSS]

I also uniform the flash hole because I believe the chamfer allows the primer flash to spread-out in a cone and start the combustion at the bottom of the powder column, as opposed to having a spire of flame shoot upwards through the powder column and ignite the whole mess of propellant at once. A slow ignition builds a consistent pressure. A dagger of flame up through the powder causes high pressures and inconsistent bullet velocities. At least that's what I believe...

Well Said I believe it too.

 

[nicholasjohn]

I also uniform the flash hole because I believe the chamfer allows the primer flash to spread-out in a cone and start the combustion at the bottom of the powder column, as opposed to having a spire of flame shoot upwards through the powder column and ignite the whole mess of propellant at once. A slow ignition builds a consistent pressure. A dagger of flame up through the powder causes high pressures and inconsistent bullet velocities. At least that's what I believe...

That's an interesting concept, and I must admit that I hadn't thought of it. I would expect that this would also contribute to lower SD's - have you found that to be the case ??? Years ago, I was using an old Shooting Chrony, which didn't calculate standard deviation. I do remember, though, that I got noticeably lower extremes spreads in my velocities when I de-burred the flash holes. I also uniform the primer pockets, but since I started doing both of these operations at the same time, I don't know if one or the other was responsible for the improved results. The most important improvement in the results was the size of the groups - they shrunk noticeably in size. If the SD's and ES's are also lower, I would expect the smaller group size to hold up out there at long range.

 

[terry 338rum]

try atlas brass, it is the most uniform in all measurements that I have used in 40 years.

 

[cape cove]

I've always deburred my interior flash holes regardless of make or punched or drilled. Never drilled a hole that didn't have somewhat of a burr on the opposite side.

 

[nvschütze]

.. .. .. have you found that to be the case???

No; I was copulating-around with a dizzying array of bullets, primers, powders and what-all, trying to develop loads for my .300-caliber and .358-caliber mildcat rifles. I was going in seven different directions at once with these smokepoles. I had my head so far up a dark & warm tube, I didn't know what I was doing or where I wanted to go with what I'd designed and built. I saw the irregular flash holes as one more thing I could fix in order to maybe get some more accuracy out of my loads. The .300-caliber was a target machine that was always a good bet for a sub-quarter group if I didn't fail the rifle. Problem was, I usually did fail the rifle...

 

[nicholasjohn]

No; I was copulating-around with a dizzying array of bullets, primers, powders and what-all, trying to develop loads for my .300-caliber and .358-caliber mildcat rifles. I was going in seven different directions at once with these smokepoles. I had my head so far up a dark & warm tube, I didn't know what I was doing or where I wanted to go with what I'd designed and built. I saw the irregular flash holes as one more thing I could fix in order to maybe get some more accuracy out of my loads. The .300-caliber was a target machine that was always a good bet for a sub-quarter group if I didn't fail the rifle. Problem was, I usually did fail the rifle...

That has long been a problem for me - not being able to change one - and only one - thing at a time. When there are three different variables that might be causing a problem, and time to make yet another trip to the range to check it out is short, it's just too tempting to change all three things that are likely to be causing us the trouble we're having. Then, even when the problem goes away, we still don't know which of the two or three changes we made fixed it. Having a shooting range right out the back door of the house would be the fix for that problem - then one could work the bugs out one at a time, and know which change we made was responsible for correcting the problem. Since I don't have that luxury, I'll have to keep doing all these individual brass prep steps and just take it on faith that collectively they are doing the trick.

 

[birdiemc]

I have that luxury but I still cant get the time to do what i want, work wife and kids....i barely have time to walk out to the shop before somebody calls me away

 

[TXAoudadKlr]

With the bore scope, are you looking inside the case or primer pocket?

 

[Sod Farmer]

Case

 

[TwoMore]

I would call this flash hole de-burring, uniforming would be making sure the flash holes are all the same size and thickness, I also sort and tru up the brass that I am target shooting with a .083" reamer and de-burr lightly after I set the base thickness from the inside with a long endmill just enough to clean it up then I set my pocket depth making the flash holes all the same thickness, my flash hole reaming fixture is a squared up and reamed block of 6061. I used the chamber reamer to put the hole thru it. Its a lot of work maybe to much but I feel it works for me on certain rifles I like little ES's By the way to the OP very good pics and thread.