Having pressure problems with 6mm ackley

[Idaho Trecker]

I have a 6mm ackley with a 22.5" barrel and am having pressure problems when reaching the max loads listed for a standard 6mm. I am shooting 95 Berger VLD's and have them .003 off the lands. I was wondering if anyone has any ideas why I am having this problem. I have the just enough headspace so the bolt closes with the slightest resistance. I am having primers flatten and slightly crater. I am using IMR 4831 and H 414. With the 414 I have only gone to 45 grains and have pressure problems. Anyone have any suggestions???

 

[bullfrog]

I have had a batch of H414 that had a much faster burn rate than the reloading manual suggested. I loaded a middle of the road charge in the manual for a 220 swift and my velocity was about 250 fps too high and I had to beat open the bolt. I have had other batches of H414 that were dead on what the manual said. Did you chronograph your loads to see if the velocities are what you're expecting?

 

[Idaho Trecker]

I did chrono the loads and that was also disappointing. I was getting 3285 average and a friend was shooting a standard 243 win with the same length barrel and 95 Berger Classic averaging 3300. I have also had the same problem shooting IMR 4831 where the velocities are low and pressures seem high. I'm not getting the extra velocity that I should with the ackley. Thanks for the input

 

[Olskoolgman]

Have you established a minimum load? What does the primers look like? What primer are you using? Usually ackley chambers dont show pressure until they are way high. The blown out walls of the case are designed to grip the chamber and reduce bolt thrust according to p.o.'s book. Therefore you dont get flattening of the primer til its way hot! I have a 6mm ackley 8 twist that i use r-22 and h-4350. I am usually 2- 3 grains over 6mm rem max loads.

 

[david g ranes]

Have you established a minimum load? What does the primers look like? What primer are you using? Usually ackley chambers dont show pressure until they are way high. The blown out walls of the case are designed to grip the chamber and reduce bolt thrust according to p.o.'s book. Therefore you dont get flattening of the primer til its way hot! I have a 6mm ackley 8 twist that i use r-22 and h-4350. I am usually 2- 3 grains over 6mm rem max loads.

Check for a carbon ring. David

 

[Justice1327]

I hope he figured it out in 9 yrs
But it is good to visit old posts from time to time

 

[david g ranes]

I hope he figured it out in 9 yrs
But it is good to visit old posts from time to time

Dang it. David

 

[Olskoolgman]

I hope he figured it out in 9 yrs
But it is good to visit old posts from time to time

Ha! Got me!! Never even looked at that.

 

[birddog 68]

Ha! Got me!! Never even looked at that.

I think we've all been guilty of it at least once and probably more.

 

[just_jon]

Dang it. David

Don't feel bad. There are two kinds of people on this forum. Those who have responded to a nine year old post and those who will eventually.