Groups went South After Primer Pocket and Flash Hole Uniform? Help

[jrhtx]

I have been using 308, LC match brass (old 77, 87) for my hunting rifles for years. Being old and hard headed, I finally decided to try and move forward upgrading my reloading process.

I had a load that was shooting 5/8” consistently in the beater ranch rifle I built (Rem 700, Shilen match SS 16.75” barrel). I decided to uniform the primer pockets and flash holes. Having shot almost all my current ammo stock, I took the processed brass and loaded 5 rounds for a check. Well, the group opened up to 1 ¼”. Everything was the same but the primer pockets/flash holes. Don’t think it was my shooting, although I am not the shooter most of you are, but the same session my Tango 51 was shooting a consistent ½”.

What’s the recommendation before I start wasting time, powder and bullets? Go up and down 0.1, 0.2 Gr? Start over completely? What I have been shooting is LC77 match brass, 210M, Hornady 155AMAX, 44.9 Varget. Yea, its not the best bullet choice but it has killed a bunch of hogs and I had them on the shelf when I started. I would like to move to a better bullet, something that I can hunt with and shoot paper for practice. Anything out there I can get in bulk?

Also, I have a batch (2x fired) I decided to have annealed. Guy here on the hide did the annealing. I had already sized the brass before annealing so now I need to resize? I don’t want to bump the shoulder any further, that was done but I haven’t checked to see if it changed. I will do that.

I am debating just starting the new load work with the annealed brass and sent off what isn’t annealed so it will all be uniform.

Your input is appreciated.
Thanks

 

[PinesAndProjectiles]

Did velocity change on the newly modified brass?

As for the annealed brass, I find it best to anneal before sizing.

I don't believe the brass measurements have changed since you annealed, but you could measure shoulder bump and neck diameter against non annealed brass and find out.

 

[XLR308]

Only five rounds is way to small of a sample size to be worrying about changing your process.
Flash hole uniforming is a fairly straight forward process and unless you are using one of the tools that sets the cut depth of the interior chamfer by indexing on the neck and had a big variation in overall case length I wouldn't worry about it.

The 155amax should be a pretty good bullet for as short a barrel as your running I allways liked the 168 and 178amax better since they didn't seem to have near as much variation as the 155 did. That could also be some of the difference you saw with your five shot test group. Just by Murphy's law you could have ended up with five bullets with more variation than normal.

 

[918v]

The bad groups is with the annealed brass?

 

[straightshooter1]

I have been using 308, LC match brass (old 77, 87) for my hunting rifles for years. Being old and hard headed, I finally decided to try and move forward upgrading my reloading process.

I had a load that was shooting 5/8” consistently in the beater ranch rifle I built (Rem 700, Shilen match SS 16.75” barrel). I decided to uniform the primer pockets and flash holes. Having shot almost all my current ammo stock, I took the processed brass and loaded 5 rounds for a check. Well, the group opened up to 1 ¼”. Everything was the same but the primer pockets/flash holes. Don’t think it was my shooting, although I am not the shooter most of you are, but the same session my Tango 51 was shooting a consistent ½”.

Uniforming the primer pockets shouldn't have much effect unless there some significant change in the primer's seating depth and/or how much the primer is being crushed (or not).

If I am to understand "uniforming" flash holes mean changing it's size in some way . . . I'd think this could very well make that kind of difference in your group size as this can change the powder ignition thereby the velocity's too. I don't touch the flash holes except for deburring the inside of the case part of the flash hole.

What’s the recommendation before I start wasting time, powder and bullets? Go up and down 0.1, 0.2 Gr? Start over completely?

First, I'd check to see if there's any significant change in velocity.

What I have been shooting is LC77 match brass, 210M, Hornady 155AMAX, 44.9 Varget. Yea, its not the best bullet choice but it has killed a bunch of hogs and I had them on the shelf when I started. I would like to move to a better bullet, something that I can hunt with and shoot paper for practice. Anything out there I can get in bulk?

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Also, I have a batch (2x fired) I decided to have annealed. Guy here on the hide did the annealing. I had already sized the brass before annealing so now I need to resize? I don’t want to bump the shoulder any further, that was done but I haven’t checked to see if it changed. I will do that.

Sizing before annealing will produce some "spring back" and tends to not give you as consistent results as you can get when annealing first.

I am debating just starting the new load work with the annealed brass and sent off what isn’t annealed so it will all be uniform.

Your input is appreciated.
Thanks

If you change your process from resizing first before annealing then going to annealing first, you'll probably need to reset your die(s) to get the consistent set back you want as annealing first will reduce the case mouth and shoulder spring back.

Annealing my brass is the first thing I do in my process after firing (other than decaping first). . . followed by cleaning.

 

[sixtyfournmor]

IMO you need to shoot some more before you worry about changing everything.

Clean your barrel, I mean get the copper out, reshoot. Jumping the gun on shooting a few rounds means nothing.

 

[jrhtx]

Bad groups were non annealed brass. I haven't loaded any annealed brass yet. Was trying to finish off a bag I had that was 2x fired.

Gun shoots better dirty.

As far as annealing, this was a first time. Kind of an afterthought and the bag was already sized.

Uniform flash hole was with a standard Sinclair flash hole tool.

I did not check velocity, I can next trip.

 

[want2learn]

please keep us posted, really interested in what you find. no doubt you checked all the basic stuff like screw tension, scope etc.

one reason why i'm so interested is that i didn't realize that my standard Lee decapping/depriming die uses a slightly larger pin than what is found in the Lapua 6.5x47 brass. I hope i didn't bugger up the brass by enlarging the hole...this stuff is so darn expensive.

 

[918v]

Bad groups were non annealed brass. I haven't loaded any annealed brass yet. Was trying to finish off a bag I had that was 2x fired.

Gun shoots better dirty.

As far as annealing, this was a first time. Kind of an afterthought and the bag was already sized.

Uniform flash hole was with a standard Sinclair flash hole tool.

I did not check velocity, I can next trip.

The unifomer cuts the primer pocket deeper. If your priming tool sucks then the primer won’t bottom out in the newly uniformed pocket. So that could be the reason for the loss of accuracy due to variable ignition.

Does your priming tool allow you to feel the primer bottom out in the primer pocket?

 

[jrhtx]

Using RCBS hand primer. I think I can feel the primer seat. Never had problems in the past. I use Lapua brass on my paper shooting guns with good results but I don't do the primer/flash hole. The LC match is just what I have been using for years in hunting rifles. Have several coffee cans full.

It will be next week before I get to hit the range again.

 

[Mr Flannel]

How many rounds on the barrel?

 

[jrhtx]

Under 300. I haven’t updated my log from the range trip.

 

[bsekf]

Do you have any of the first loading that shot 5/8 left? Before I went nuts changing things, I would see if the rifle still shoots the old reloads 5/8.

Bill

 

[RegionRat]

Do you have any of the first loading that shot 5/8 left? Before I went nuts changing things, I would see if the rifle still shoots the old reloads 5/8.

Bill

Agree. It is good to have some reference ammo to debug your rig. In 308 the use of 168 SMK FGMM is common for reference use.

If at all possible, get velocity stats on the loads that your rig likes so you can see if the new loads match up or if they have drifted in speed or SD.

 

[Rhed]

I never thought that primer pocket uniform would affect accuracy. Then again I use Lapua and Nosler brass. I never did do anykind of uniform to the pockets. And I also SS tumble so pockets come out really clean. No affect in accuracy.

Deprime
SS tumble
Anneal
Size (without button)
Trim, debar, chamfer ( if needed again)
Prime
Drop
Seat

 

[Mr Flannel]

Under 300. I haven’t updated my log from the range trip.

No issue there then probably, although barrels can speed up early in their life and the velocity increase might throw your load accuracy out. Worth checking.

 

[jrhtx]

I only have 6-7 rounds left and would rather hold these for hogs for now. They seem to be bypassing me for now. Cool front next week may have them active again.
I have plenty FGMM I can test next week.
I may size the annealed brass this weekend and just start over. I have to start it sometime.
The data on the old load
2609 FPS avg
5.2 SD
10 ES

Question on annealed brass though. Are you having to reestablish your load date every time you anneal your brass?

 

[jcam]

I found that if I anneal after sizing there is resistance with bullet seating. So I stick to resizing after annealing.

I didn’t see any change on load data with annealing.

 

[FLIGHT762]

I would like to move to a better bullet, something that I can hunt with and shoot paper for practice. Anything out there I can get in bulk?

Hornady makes a 150 Interbond and Nosler makes a 150 Accubond for hunting. They are pricier than the match bullets. Seeing you have a short barrel, the 150's might be better. You could also go to the Hornady 178 ELDX, but the velocity will be lower with the short barrel, but may work for Hogs.