Author Topic: Flash hole uniforming (Read 481 times)

Rum River · « **on:** March 14, 2006, 01:40:53 AM »

Anybody out there able to tell me how much performance improvement they may have had by uniforming their varmint-caliber flash holes?

The reason I ask, I only now started doing this. I'm getting into black powder cartridge, and my .45-120 cases had some serious burrs. Bought the Lyman tool and removed said burrs, but haven't done extensive load development yet.

Since I'd found burrs in those cases, I started checking out a 1000+ batch of .243 WSSM brass I'd been given as a gift. A lot of these virgin/unfired cases also had some serious burrs.

I'm contemplating going through all of my .223 cases as well. I've had some .600" groups (outside measure), but I'm always trying to squeeze them in there a little tighter.

Grumulkin · « **Reply #1 on:** March 14, 2006, 01:55:09 AM »

If you have a gun only capable of 3 to 4 MOA, you probably won't notice any difference from deburring/uniforming the flash holes. If you have a gun capable of less than 1 MOA, you may notice a difference. While you're at it, also check to see that the flash holes are perfectly centered in the primer pocket, in my opinion, discarding the cases with eccentric flash holes has more of a potential of making a difference than deburring and uniforming.

Questor · « **Reply #2 on:** March 14, 2006, 02:58:25 AM »

I looked into it for .223 and decided not to do it because I was already getting 3/4" center-to-center groups and there was no need to improve on that. However, for those who want the extra accuracy, it certainly won't hurt. I don't think any serious rifle competitor uses brass that hasn't had the flash holes uniformed.

On the first loading I inspect each case, including the flash hole. With the Winchester brass I use for rifle cartridges, I've never seen anything worrisome. Out of a hundred cases, one case typically has a neck that's been deformed in handling, but that's quickly solved by sizing the case. If I saw a problem, I'd be uniforming my flash holes too. I don't clean primer pocket holes either, and it doesn't seem to be a problem. The pockets are never so encrusted with fouling that I can't seat the primer properly.

victorcharlie · « **Reply #3 on:** March 14, 2006, 03:19:46 AM »

A fellow can spend a lot of time on cases. I guess, to some the payback is worth it. In years past, I have been "anal" about this and would spend many hours on my brass. IMO, this is one area where the paybacks are small, but they do exist in some rifles and some calibers.

If you have a blue printed and squared action and everything about your rifle is as close to perfect as possible, and you have a perfect day to shoot..and a very steady bench and rest...why not have perfect ammo too?

I really doubt shooting a factory rifle with a sporter length and weight barrel you'll notice much difference. I don't chuck them in a drill press anymore. I might run a drill bit through the hole quickly depending on caliber and rifle combination but I don't spend near the time I used to on this type thing.

Why not do 20 and compare them to 20 cases you haven't worked on....then post the results......

ajj · « **Reply #4 on:** March 14, 2006, 04:26:16 AM »

I'm no expert but I read a lot. I think it was Newick's book and at least one other that said flash hole deburring was the one thing you should do if you wanted to do just one brass prep task, before weighing, primer pocket uniforming, neck turning or anything else. It certainly stands to reason that you need to be playing with a reasonably accurate rifle to expect any difference.
One theory is that a few of the cases will have really big burrs on one side and that the process of weeding those out is where the benefit comes from. If you decide to do a comparison, you might try checking with a light and a glass, looking for a few cases with big, obvious burrs and comparing those with the prepped cases. Finally, note that the large burrs are often blown off with the first firing so you might re-inspect after you've done the test.

Questor · « **Reply #5 on:** March 14, 2006, 05:42:48 AM »

A book called the "Precision Shooting Reloading Guide" or something like that has all the steps in it for doing meticulous case prep for target shooting, including benchrest. It's spiral bound and Cabelas sells it. I thought it was interesting, and would consider it indispensable if I were seriously into maximum rifle accuracy. They cover benchrest, high power, 30-06 for M1 target shooting, etc.

lilabner · « **Reply #6 on:** March 20, 2006, 05:39:44 AM »

Can't answer your question as I'm just getting started deburring flash holes. The rifles shoot sub moa without flash hole treatment. I think my record keeping is good enough that in time I'll know the answer. The Lyman tool I bought is a very nice one and easy to use.

Steve P · « **Reply #7 on:** March 20, 2006, 03:54:36 PM »

I debur the flash holes, use a primer pocket uniforming tool, and make sure my brass are trimmed. When I hit targets at 500+ yards with my Contenders and XP-100s I am glad that I do it. I cannot say how much it helps, but I spend time to do it for my competition guns.

Steve