Light vs Heavy and Extreme Spread

[tim_w]

No you have something more going on. I was just agreeing the powder change can effect es/sd.

I gave to think its an ignition issue stemming back to the issue around the firing pin assembly and pierced primers. I had though replacing the assembly would be a good step.

 

[Frog4aday]

Gun had high ES when it was 243. Now it is 6mm and still problems. Forget barrel, powder, case fill, etc. You've messed w/the firing pin twice now. Trust your gut. Replace the firing pin & spring.

 

[crazyhorse]

Have you tried sticking with one powder (preferably with good case fill) and seeing if you can find a "node". Randomly switching powders and bullets hoping to land in the sweet spot is akin to throwing $%*! at the wall to see what sticks.
There are many good threads on here detailing the process.

I've found over the years by starting with a known good powder for a particular caliber and spending the time to find the sweet spot produces far better results.
Sometimes its in the top of the load range and others near the bottom but when you find it you've eliminated a major variable in consistent LR accuracy.

 

[rustyshackleford]

Have you tried magnum primers? In my particular case, lighting off hunter in 30-06 gave wild numbers and weird stringing with CCI 200's. Switching to WLRM gave sub 10 ES and ~1/2 MOA. Shooting Tac in 308 gave me a weird group also which makes me think it's more a function of ball powder than case capacity

 

[david g ranes]

I know 4 people who are shooting 6mm rems me included we all started out with 4350 and have since went to h4831 48 grains seem to wrk great in all of our guns they were all cut wit the same reamer if that makes a difference on bartiien barrels only difference from you we are shooting 105berger. David

 

[codyadams]

I would replace your fireing pin and spring, as it has been modified. I doubt that will fix your problem though, you have good performance with the heavier bullets as stated. Cratering is likely not totally due to the firing pin shape, if protrusion is good and you want it gone then have your firing pin bushed. Sloppy firing pin holes cause craters.

As far as velocity spread, if you want it more consistent with the lighter bullets, after you have tried all that you stated, and it still doesn't work with the light pills but does with the heavies, it simply doesn't like the light bullets. Get a new barrel. After all that load developement and being rechambered, your barrel may be getting towards the end anyway.

 

[IHFarmer07]

Don't know if this is an issue with a 6mm rem, but have you tried to see if it has the "dreaded doughnut" in the neck/shoulder junction. That can mess up neck tension to the point of it showing pressure signs and high es/sd.

 

[Tiny Tim]

My last 243 didn't like to push the light bullets fast. Like 300+ fps below max. Shot great at those velocities, but certainly not what I was looking for (why would you load light bullets in a 6mm other than for SPEED. LOL)

 

[RD57]

I also have a 35P and I don't trust it's readings from October - March. The low sun angle has a terrible influence on the velocities. This was noted here in E. TN and in Colorado, but had no visible effect in the ugly lower corner of Alabama when I was stationed there. I have very low ES & SD with my 243 Win using H4350, Varget and H4831. What are you weighing your powder charges with and do you use the same technique each and every time? When I quit using my electronic scale and went back to my old RCBS balance beam scale the ES/SD came back to the low readings I used to get ... and I never do it when the AC or Heater blower are actively on. It could be any number of things though, including brass hardness and how many times between annealing. Good luck solving the mystery!

 

[Mike Matteson]

I agree. But I've tried, H4350, Varget, Big Game, Hunter, Staball 6.5, RL-16, RL-17, RL-15, H4895 and W760.
I tried these with 55gr Nosler, 55gr Sierra, 58gr Hornady, 65gr Berger, 65gr Hornady, 69gr Berger, 70gr Sierra and 75gr Hornady.
I get mostly groups between 0.75" and 1" at 100 yards with the occasional group less or more. However, when I find something that seems promising it isn't repeatable.

I load for a 220 Swift and I use IMR 4064 but with a Fed. 210 primer with a 55 grain Sierra Spitzer. It groups at almost .28 moa at a 100 yards. That wasn't even cutting necks or any trick things that are done now days.
No problem at 300+ yards taking out ground squirrels. The farmers love us to take out their squirrels. It wasn't even fair shooting under 200 yards at the ground squirrels.

SSS
Mike

 

[GTN]

I have a 10twist 6mm rem 700 action and shilen barrel that was the same way. It simply did not like lighter bullets. I was sitting there scratching my head one day after trying many different 70-85gr bullets and powders and a load in the manual jumped out at me, 100gr bullet with 7828ssc. Tried that and shot lights out. Finally settled on the 95gr Berger and 7828ssc, br2 primer, I can't remember what my es is on it without looking in my notes but I know it's less than 20. It's a solid 1/2 minute gun out to 600.

 

[deertroy1]

Mine shoots the heavier stuff fine.

 

[Betarider]

I'm noticing I cannot get consistent velocities when shooting light bullets in my 6mm Rem. It is a McGowen barrelled Savage. I'm starting to think it's because of the firing pin assembly as it also gave high ES when it was new as a 243 Win. Unfortunately it has the one piece firing pin. Firing pin protrusion is good at 0.053". It severely craters primers with even mild loads. I was told this is a result of too sharp a firing pin tip. I made it more blunt and it helped with the cratering but did not eliminate it. I made it more blunt and it wouldn't fire. I put it back and it fires but the cratering is back.
I recently tried some 100gr bullets with RL-22 and ES was down in the low 20's and teens. With bullets 75gr and under it's anywhere from 50 - 100 fps for five shoots. Accuracy isn't all the great either.
I've tried all the little things like different brass, different bullets (Nosler, Berger, Sierra, Hornady), different powders (H4895, Varget, RL-15, RL-16, Staball 6.5, H4350, Big Game, Hunter, W760, etc.), different primers, weighing cases, cleaning up the necks, etc.
I was wondering if anyone else has experienced having difficulty getting low ES with light for caliber bullets?

Try VihtaVuori powder stops all that ES you are fighting

 

[Calvin45]

All things being equal heavier bullets will almost always give lower es numbers. This makes sense when we think of how the energy of a projectile increases exponentially with velocity. It's not that heavier pills are more consistent, it's that the same natural fluctuations, the tolerance, in the muzzle ENERGY exist with both heavy and light bullets, the lighter the bullets the more this energy fluctuation shows up as wide ES numbers.