To ream or not to ream

[Joe-ker]

your flash holes?

Never done it myself till now.

I did a side by side test yesterday. .223 hand loads exactly the same but half were not reamed. The unreamed were 1/2 MOA. The others I didn’t even measure they were so terrible. I really don’t know what to say. I’ll have to try it again.

[milboltnut]

maybe uniform the flashhole where it enters inside the base of the case to remove the burrs but not the complete flash hole that is between the pocket and inside base, no. I get bug hole groups with my M70 06 without it.

I learned that messing with brass, will enhance accuracy as long as the platform you're shooting is consistent. I had to bed my rifle to see better brass prepping results.

[nhyrum]

Reaming will ensure the bottom of the primer pocket is square, and will usually chamfer the mouth of the primer pocket. Flash hole uniforming and deburrung will usually be more effective.

It also depends on how heavily you reamed them. I usually only do a twist or two by hand. Kind of like turning necks, it's a once and done thing.

Sent from my SM-G996U using Tapatalk

[milboltnut]

Reaming will ensure the bottom of the primer pocket is square, and will usually chamfer the mouth of the primer pocket. Flash hole uniforming and deburrung will usually be more effective.

primer pocket uniformer does this not a reamer. Reaming flash holes has nothing to do with primer pockets being square.

[Unclenick]

Joe-kr,

What diameter reamer did you use? Generally speaking, reaming vs. not reaming makes differences of a fraction of one MOA. So unless you really altered the cases grossly, something else caused this problem (loose stock screw, loose scope base, scope internal problem, etc.) and the fact it happened with the reamed cases is a coincidence (contrary to popular police procedural dramas, in the real world, coincidences do happen). Is there any chance you uniformed the bottoms of the primer pockets, too? Sometimes folks fail to seat primers completely and firmly after first making that change. Or they make the change but their firing pin protrusion is so marginal they no longer get consistent ignition with the deeper seated primers.

[Joe-ker]

Originally Posted by Unclenick

Joe-kr,

What diameter reamer did you use? Generally speaking, reaming vs. not reaming makes differences of a fraction of one MOA. So unless you really altered the cases grossly, something else caused this problem (loose stock screw, loose scope base, scope internal problem, etc.) and the fact it happened with the reamed cases is a coincidence (contrary to popular police procedural dramas, in the real world, coincidences do happen). Is there any chance you uniformed the bottoms of the primer pockets, too? Sometimes folks fail to seat primers completely and firmly after first making that change. Or they make the change but their firing pin protrusion is so marginal they no longer get consistent ignition with the deeper seated primers.

It’s a Lyman flashole uniformer, I guess I shouldn’t have used the term reamer. It measures about .078. I just gave it a couple light twists until you feel the burr from cutting the flash hole is gone. This is the only difference in the loads.

The first group I shot was the uniformed ones…..I forgot to bring some rounds to warm up the rifle as well as myself so I kinda discounted those. I then shot a group of un treated ones and it was an exceptional group. So I decided to not let myself know what I was shooting after that……to remove any possible bias.

Once again the uniformed group was terrible and the other was 1/2 MOA.

Yes the primer pockets received a light touch with the uniformer. I feel confident they were all seated firmly as I check them visually if that means anything.

Just weird. Gonna have to try again.

[7.62 man]

As long as the depriming pin goes through it, that all the reaming or cleaning I do.
I do wet tumble with SS pins, that takes care of most of the cleaning.
If I was OCD & had to tweak every little bit of accuracy out of a round then I probably would.

Just don't get too carried away with it.

[Joe-ker]

Originally Posted by 7.62 man

As long as the depriming pin goes through it, that all the reaming or cleaning I do.
I do wet tumble with SS pins, that takes care of most of the cleaning.
If I was OCD & had to tweak every little bit of accuracy out of a round then I probably would.

Just don't get too carried away with it.

I clean with SS occasionally too but for these I just touched up the pocket a bit to clean.

But to be more clear the uniformer I am talking about goes in through the case mouth to take the burr off the inside.

[Unclenick]

Ahhh! It's a flash hole deburring tool, not a reamer per se. Sinclair sells the reamers for uniforming flash hole diameters, but that's an extra step on top of deburring. I've had good luck deburring flash holes to get the older spherical powder formulations to burn more consistently and always got either no effect or an accuracy improvement, depending on the load and primer used. I'll mention that I use the Redding version of this tool because it has a collar around the little #2 center drill that runs into the web to stop it from cutting too deeply even if the centering collar position is off for the particular case being deburred. I don't know if you think you've had and cutting depth uniformity issues or not with the Lyman version.

So I'm still inclined to think it is most likely something else going on here that we just haven't identified. In your shoes, I would get out every measuring tool I've got and subject first the cases and then the live ammo to every measurement I can make to see if I can find a difference. Set the ammo up in a straight line and see if the tips of the bullets are still lined up to check for out-of-square heads. Look at concentricity. Check case weight and neck wall thickness uniformity for any difference in runout. Check the as-fired case water overflow capacity, et cetera.

Incidentally, the 1/8" flash holes on the 45 cases in the photo from 7.62 man are used to prevent primer blackout in primer-fired wax bullet loads and to keep DDNT "green" primers from backing out too hard. Folks who've reloaded them in standard 45 loads with standard primers say they cannot detect a performance difference. But that's pistol shooting, not rifle shooting.

[Joe-ker]

Thanks Unclenick. Yes the Lyman tool has the collar to keep deburring uniform to each case.

These cases are all same headstamp, we’re trimmed and checked for length, concentricity, and after bullet seating were checked with comparator. It was my goal to eliminate as many variables as possible. I haven’t capacity checked the cases but that would be a good thing to check. Bullets were hornady Vmax so I expect their quality was good.

Unless the capacities are actually off, the only variable other than the flash hole debur is myself…..which I know is the most likely……but just funny how it worked out.

[zeke]

Perhaps the benefits depend on what the cases look like before? If getting a batch of cases that am planning on using several times with ill regular/burred up flash holes, they get uniformed. While never measured them, am betting the dia is increased slightly.