Gun and/or reloading issues. Need help.

[fly2cast]

I have a 6mm bolt action and reload my own ammo. I don't do a lot of reloading but I believe I know mostly what I'm doing. For the last several years I have been using a recipe that works for my gun and haven't changed it. I went out to sight in my rifle a couple of weeks ago and my groups were terrible. I thought maybe I had did something wrong during the reloading process. I reloaded a new batch with brand new powder and primers and being very careful to make sure everything was performed correctly and accurately. The groups were again terrible. Like maybe a 3 inch group at 100 yards. I then noticed that some casings were denting and I believe that accuracy and the case denting are related problems. However, I have no idea what might be causing the cases to dent. I've never noticed this in any of the years before.

I'm using 39 grains of IMR 4350 and a 100 grain bullet and large rifle primers.



Any ideas?

 

[luvcatchingbass]

Only time I have had case denting it has been because of too much case lube, buddy had an issue with that as well.

 

[SDMF]

Only time I have had case denting it has been because of too much case lube, buddy had an issue with that as well.

Too much case lube is also the only cause I've ever seen.

If those are fired cases that haven't been run through the die presenting the dent, then you likely have something lodged in the chamber.

 

[BP338]

Did you notice the divot before you fired it? Too much lube when sizing can create divots which makes the shell casing capacity smaller which messes with the pressure coming out when fired. That can screw with things.

 

[fly2cast]

I checked the casings before they were fired and they were fine. It happened on two of the 15 shots I fired on Friday.

 

[guywhofishes]

wow! that’s nuts

loads too light leading to pressure too low? neck not sealing and pressure is blowing back down along shoulder?

 

[bucksnbears]

Makes zero sense to me.
The dents should be there before firing and blow out after firing.

 

[PrairieGhost]

I don't think you could extract a case if there was an obstruction that large in the chamber. Check before you shoot again. I have only seen that type of dent from to much lube and often with dies that don't have a hole in the side to allow air to escape. I however don't think it's your accuracy problem. So many cleaners these days say they remove copper fouling, but do a very poor job, or damage the crown when a drop forms at the end of the barrel and you let it set to dissolve more copper. The best and safest I have found to date is Wipe Out. I like the Wipe Out foam and let it set overnight. Follow that up with a carbon solvent then checks it one more time with a copper solvent. My Savage barrels are very accurate, but build up copper extremely fast. Fast as in accuracy drops off after 50 rounds. I replaced them with criterion barrels and they show very little copper after 300 rounds.

Normally it's the shoulder that dents from to much lube not the side of the case, but?????

 

[Fly Carpin]

How many reloads have you done with that brass?

 

[fly2cast]

How many reloads have you done with that brass?

Unless I got them mixed up, they were in a bag that I had marked as "Shot 1x". So this would have been the second firing with this brass.

- - - Updated - - -

As far as accuracy, it's possible that there is something wrong with the gun/scope and is separate from the brass issue. The scope is an older Nikon Buckmaster which isn't a bad scope but definitely not top of the line. I believe it's secured properly as I checked the screws to make sure they were tight. I've had scopes go bad before and given me similar problems.

 

[7mmMag]

[MENTION=1035]wby257[/MENTION] any idea??

 

[guywhofishes]

wow! that’s nuts

loads too light leading to pressure too low? neck not sealing and pressure is blowing back down along shoulder?

is that soot near the entry point of the dimple? (evidence of blow by)

- - - Updated - - -

http://forum.accurateshooter.com/threads/strange-dents-in-fired-cases.3770985/

 

[Wags2.0]

I’ve cracked many necks from 1 too many reloads, had a couple cases separate, and blown out primers from me pushing my luck, but I’ve never seen that before

 

[Captain Ahab]

I have no clue, but if you went and picked up some factory loads and fired them you would narrow down if it was your gun or the load.

 

[all4eyes]

Never seen dents that low from to much lube, usually in the neck. I'd throughly clean the barrel, then shoot some factory ammo and check point of impact. Also check your bases, had a savage that I couldn't keep bases tight. I wouldn't ru,e out the scope, but start simple and go from there.

 

[Petras]

While I've never seen this before myself, my money is on not enough pressure in the case to seal the neck, but enough to seal the body of the brass in the chamber creating this dimple in the brass. The charge weight you are using is actually under the minimum recommended powder charge according to the Hodgdon website. They list 40grains of IMR4350 as the minimum charge for a 100 grain bullet.

ETA: If it were my gun and my reloads I definitely wouldn't be shooting any more of these loads as they are now.

 

[Kentucky Windage]

Strange. Like others have said, I’ve seen denting from too much lube at the shoulder of the case when I’m resizing several hundred cases in a session. I’ve never seen denting on the body or neck though. I would also recommend checking and cleaning the chamber and throat of the rifle barrel.

 

[Sum1]

Have you been colluding with the Russians??

 

[LBrandt]

Run some factory ammo and see if there is a problem. Quick way to find out, otherwise just guessing to much case lube. I had that problem on 22-250 but not as bad as what you show.

 

[Wildyote]

Does the case have sent before you shoot it?
It should form to your chamber after firing. If you had an obstruction in the chamber causing a dent like that you would be able to fully chamber anyways. Take your rifle to a gunsmith and have him check it out.