Re: 22-250AI & 55gr V-MAX problems

05 September 2004, 02:56

Quote:

bjld:

Possibiities that come to my mind are:

1. Is it possible that your powder has been contaminated or mis-labeled?

2. Is it possible that your scale needs calibration?

3. You have a bad lot of bullets that are oversize or too hard or soft in the jacket material. (try a different box--lot #)

4.You have a bad lot of primers

5. Is your sizing die pushing the shoulder back too much?

6. Does your rifle have a tight neck. If so what is your neck clearance?

It would help if you were shooting through a chronograph and knew the velocity at which things started going wrong. Also, I'm wondering what the load was that you were shooting with the 69 gr bullets?

knobmtn

1. I'm pretty sure the powders are OK.

2. I rezeroed the scale, and it's been reliable for the couple of years that I've had it. Admittedly, it's a beam balance and I don't have any check weights.

3. The bullets mike at 0.2241". With moderate starting loads, the pressure shouldn't be too high, even with hard jackets, should it?

4. I've already used 700 of the 1000 in the brick of primers without any problems.

5. The cases have only been neck sized.

6. The necks have several thou' of clearance.

The chrony clocked 3800fps with my starting load. I would have expected to achieve that with a hotter load, but I just thought "great, here comes 4000fps!" and missed the pressure warning from the mark left by the plunger ejector.

I thought pretty much along the lines you have suggested. The rifle may just need lighter charges. I think it will still give me somewhere near the velocities I want.

What really puzzles me is why the bullets are keyholing. It suggests thst the bullets are under-stabilised - but it shoots 69gr MatchKings just fine! And the two shots that left traces of lead in the target suggest that those bullets were breaking up (over-spun). Do excessive pressures make bullets unstable or disintegrate in flight?

I bought a bulk pack of the V-MAXs. I need them to work!

Thanks

Ben

05 September 2004, 03:24

243winxb

The key hole and smear of lead on the target when i had the problem with a 243win was in the nra rifleman. They said if a bullet is undersize in dia. or the groove dia. of the barrel is larger then the bullet, the hot gasses blow by the bullet while in the barrel. The tip of a lead spitzer bullet will be come liquid in the barrel and remain so in the air as the bullet rushes to the target. This will leave a lead (looks like grease) smear on the white paper target. If your gro0ve dia. and bullet dia. is ok. Then the bullet is just breaking up from a rough chamber throat area. The bullet jacket can be weakened by the rough throat of the chamber.Small cuts are made in the bullet jacket, making the bullet weak. Bullet well deform or come apart after leaving the barrel.Polish the throat/chamber area.The 1 in 10 twist maybe to much spin for the Hornady 55 gr bullet.The 1 in 10 works better with heavy long bullet??

05 September 2004, 03:35

Savage99

Stop shooting the rifle as all loads over max and should not be if your powder weights are correct for the AI chamber.

I would take the gun back to the smith and have him figure it out.

If I were the smith I would check the bore and groove diameter of the barrel.

05 September 2004, 02:30

knobmtn

bjld:

Possibiities that come to my mind are:

1. Is it possible that your powder has been contaminated or mis-labeled?

2. Is it possible that your scale needs calibration?

3. You have a bad lot of bullets that are oversize or too hard or soft in the jacket material. (try a different box--lot #)

4.You have a bad lot of primers

5. Is your sizing die pushing the shoulder back too much?

6. Does your rifle have a tight neck. If so what is your neck clearance?

It would help if you were shooting through a chronograph and knew the velocity at which things started going wrong. Also, I'm wondering what the load was that you were shooting with the 69 gr bullets?

knobmtn

05 September 2004, 06:38

bartsche

I have spun a number of jackets off light bullets with fast twist barrels and at the same time was surprised with what I thought at the time to be unusually high pressure. Although key holeing can accure with fast twists usually you see coma shaped holes with some lead disintergration left on the target.The high pressure might also be attributable to the twist as it was for me, but than again there are a plethora of possibilities one of which I ran into yesterday and will post as soon as I'm done here.You will just have to learn what is safe to load for your rifle and not use data that was intended for 1 to 14 twists.The V-Max may be a lot like the TNT varmint bullet and start to get erratic when going to fast or spining more than it was designed for. I say this not in jest, but perhaps with the V-Max you might want to slow it down with a case full of 5010.

roger

05 September 2004, 04:08

243winxb

where are the primes blowing out at? At the firing pin strike point or on the side of the primer cup? What brand of primers?

04 September 2004, 23:42

bjld

G'day all

I began with 34 grains of Varget and when I got to 37 grains I popped a primer. I should have noticed the ejector mark on the base of the cases as a warning sign that all loads were running at high pressure, but I just didn't expect a primer to go with these loads.

But what has me most puzzled is that most of the bullets were keyholing in the target. The only two that didn't had left a ragged hole with a smear of lead around it. Needless to say, accuracy was non-existent.

The barrel has a twist of 1/10, so the bullets should be stable enough. And I didn't expect V-MAXs to go to pieces at 3800fps.

I tried just one shot with 37gr of H4350 - blown primer. I was sure this was going to be a safe starting load.

So what's going on? The rifle was shooting 69gr MatchKings OK before I started shooting the V-MAXs, although extraction had seemed to be sticky for the first time with this well tested load.

The rifle has only shot about 300 rounds, the barrel is new and the gunsmith is competent. The barrel was cleaned 40 shots before the shot that blew the primer. Bullets were 20thou off the rifling.

Any advice would be appreciated.

Ben

05 September 2004, 16:36

bjld

Quote:

I have spun a number of jackets off light bullets with fast twist barrels and at the same time was surprised with what I thought at the time to be unusually high pressure. Although key holeing can accure with fast twists usually you see coma shaped holes with some lead disintergration left on the target.The high pressure might also be attributable to the twist as it was for me, but than again there are a plethora of possibilities one of which I ran into yesterday and will post as soon as I'm done here.You will just have to learn what is safe to load for your rifle and not use data that was intended for 1 to 14 twists.The V-Max may be a lot like the TNT varmint bullet and start to get erratic when going to fast or spining more than it was designed for. I say this not in jest, but perhaps with the V-Max you might want to slow it down with a case full of 5010. roger

G'day Roger

I chose 55gr bullets for my 1/10 twist barrel because I thought they were better suited to it than lighter ones. The light bullets I've shot in the past with a 1/10 twist 223 just turned into clouds of lead vapour.

The keyholes looked like a perfect profile of the bullet. The sharp point gave the impression that the plastic tip of the bullet was intact when it went through the target sideways. This leads me to believe that the jacket was completely intact for these particular shots.

The lead disintegration around the impacts that did not keyhole does suggest that these bullets had at least partially separated from their jackets.

I used the Sierra manual's data for the 55gr BlitzKing as a starting point for my load development. For the standard 22-250 (1/14 twist), a starting load of 37gr of H4350 is suggested. Even with a 1/10 twist, I thought this must be a safe place to start with the Ackley improved version, but the primer was blown clean out of the case!

I started with 34gr of Varget, which is 0.7gr less than Sierra recommends as a starting load for the Ackley. I clocked over 3800fps, where Sierra got 3400fp. They achieved a maximum of 3700fps with 37.1 gr. This was a warning sign I missed, plus I did not notice the ejector mark on the cases. Live and learn. So maybe the rifle will give me the velocities I expect with much less powder than normal, but does high pressure make bullets behave this erratically?

The 69gr MatchKings have shot just fine within the range of H4831SC suggested by Sierra, with extraction starting to become sticky at 43gr. However, their data was developed in a 1/8 twist barrel.

I bought a bulk pack of the V-MAXs because I thought the V was for velocity! I'm hesitant to try shooting some BlitzKings, which I believe would take the velocity and twist rate, until the pressure, keyholing and jacket separation issues are addressed.

Something funny is going on.

Your advice is appreciated.

Ben