What's going on here?

[olddav]

What's going on here?

I am trying to develop a load for my 338-06 using Barnes 160 grain TTSX. Using info I received from Barnes I performed a ladder test staring at the min and progressing to the max in .01 grain incriminates. During the ladder test I saw no signs of pressure with any load. I settled on 61.3 of H 335 (best node) and began testing seating depth. Using a bullet comparator I seated the bullets at 3.595 to 3.635 in incriminates of .005, and loaded 3 of each.
Started shooting the shorter bullets first (3.595) and progressed to the longest (3.635). Everything was going as it should (no signs of pressure) until I got to the final six. The first three were a little tight ejecting and the final two I shot blew out the primers. Stopped right there! Keep in mind I shot these very same loads without any problems not more than 20 minutes prior to blowing the primers out. Any ideas as to why this is happening?

Here are the details for the loads
Remington Brass (30-06 new and resized)
Winchester WLR primer
Barnes TTSX 160 grain bullets
H335 powder (61.3 grains)
Barnes Manual states min to max are 57.0- 62.0 of H335
All measurements given are to the Ogive of the seated bullet.

[DanSavage]

What seatin depth did you shoot the ladder with?

[Boudin]

All brass trimmed to the same length?

[olddav]

Seating depth during ladder test 3.595 with all brass measuring 3.484 (+/- .003).

[BarrelBurner]

The lesser jump as you advance toward the lands will tend to increase pressures. With the shorter rounds the bullets get a running start before they hit the lands vs the pressure spike it creates if the bullets touches the lands right of the bat.

[olddav]

The rifle is a savage with a Shilen barrel (338-06). The test consisted of 3 bullets per seating depth, I fired 2 of the 3 sets before blowing primers. I fired the shortest to the longest , one each as a set. Once a set was fired I repeated the process a second time except On the second set I started with the longest and worked down the the shortest. On the Thrid set I started in the middle and move out to the from there.

Shot sequence,
3.595, 3.600, 3.605, 3.610, 3.615, 3.620, 3.625, 3.630, 3.635. (10 min break)
3.635, 3.630, 3.625, 3.620, 3.615, 3.610, 3.605, 3.600, 3.595. (10 min break)
3.600, 3.605, 3.595, 3.625, 3.620, 3.630,( 3.615, 3.610 blown primers).

[LongRange]

Have you shot this brass before? weighed it? Did you happen to look in the cases after powder was in the cases before seating bullets?

Sounds to me like you may have a few odd pieces of brass with a pretty big difference in case capacity causing high pressures.

[earl39]

Hodgdon shows 53 to 57 grains with H335 and the Barnes 160gr bullet. Looks like you might be a bit warm. Showing bullet maxs out a little over 3000fps.

[olddav]

LongRange,
I have shot this brass before, (new Remington resized). I load the powder (weighting the charge) and then seat the bullet before going to the next one. I then double check the length with a bullet comparator.

earl39
Barnes email me a page stating min 57.0 and max 62.0 of H335 for the TTSX 160 grain bullet (as in OP), also as stated in the OP during the ladder test no charge weight showed any signs of pressure up to 62.0 grains.

[earl39]

just because a load is safe in one rifle does not mean it will be safe and another rifle. prehaps you should check the velocity against the book velocity for that load

[jonbearman]

I think as your coal got into the lands or very close it causes a spike in pressure and being 33 cal it would present itself when you get close or into for sure. You need to do a ladder with the bullets seated as long as you want them and work up slow to find pressure.

[JW]

I agree with jonbearman's post above

Asking this because it happened to me
Was the ambient temp lower when you ran the initial ladder test?
I had a good load (different caliber) with H335 worked up in cool weather that was way to hot in warmer weather
Hope you get it worked out
Jack

[Jamie]

Does sound like you are too close to the lands.

[LongRange]

Hodgdon shows 53 to 57 grains with H335 and the Barnes 160gr bullet. Looks like you might be a bit warm. Showing bullet maxs out a little over 3000fps.

the reason i asked those question is because in the height of the shortage i bought 3 boxes of 180g Winchester ammo for my 300wm. i pulled the bullets as i just wanted the brass. i loaded up 30 of the 60pcs and they shot great. the next weekend i loaded the other 30 and 10 or 15 rounds in blew primers out of 2 cases with the same powder charge that shot fine...i went home pulled the bullets and weighed the fired cases with water and the 2 that blew primers were 5gs heavier.

[sixonetonoffun]

Seems like a pretty hot load. WW brass I see loads up to 62gr RP brass might have a little less volume.

At 61.3 your fps would have to be about 3200. I think LongRange is right on with weighing the brass to see if the popped primers were from heavier lower volume cases.

Sorry just read your last post!

[earl39]

earl39
Barnes email me a page stating min 57.0 and max 62.0 of H335 for the TTSX 160 grain bullet (as in OP), also as stated in the OP during the ladder test no charge weight showed any signs of pressure up to 62.0 grains.

Dav, not to sound redundant but you changed something and are not willing to accept the results which in this case seems to be excess pressure. You didn't have pressure problems till you moved the bullet out. Did Barnes say how far off the lands they seated their bullet? OAL means squat unless you know where your lands are in relation to bullet ojive. Want to get close to the lands? Start over with the bottom load and a jammed bullet and work up. Then when you reach max pressure you won't be surprised by high pressure when you back the bullet away from jam.

[LongRange]

The rifle is a savage with a Shilen barrel (338-06). The test consisted of 3 bullets per seating depth, I fired 2 of the 3 sets before blowing primers. I fired the shortest to the longest , one each as a set. Once a set was fired I repeated the process a second time except On the second set I started with the longest and worked down the the shortest. On the Thrid set I started in the middle and move out to the from there.

Shot sequence,
3.595, 3.600, 3.605, 3.610, 3.615, 3.620, 3.625, 3.630, 3.635. (10 min break)
3.635, 3.630, 3.625, 3.620, 3.615, 3.610, 3.605, 3.600, 3.595. (10 min break)
3.600, 3.605, 3.595, 3.625, 3.620, 3.630,( 3.615, 3.610 blown primers).

earl im not sure if you missed this post but he had already shot a group prior to the group that blew primers at the same charge and seating depth with no issues.


Dav, not to sound redundant but you changed something and are not willing to accept the results which in this case seems to be excess pressure. You didn't have pressure problems till you moved the bullet out. Did Barnes say how far off the lands they seated their bullet? OAL means squat unless you know where your lands are in relation to bullet ojive. Want to get close to the lands? Start over with the bottom load and a jammed bullet and work up. Then when you reach max pressure you won't be surprised by high pressure when you back the bullet away from jam.

[olddav]

I weighted the cases that blew primers and spot checked others, the cases with the blown primer were lighter than the rest.
However the temp was cooler when I performed the ladder test so I guess I could be on the edge.

[BarrelBurner]

One other thing that maybe a factor if you are nearing the edge of you pressure limit I just snapped on, your note about firing these in 20 min or less. If I counted right you logged 26 rounds in that time frame. that barrel had to be pretty hot in that time frame. That may be a contributor being it occurred at the end of the session.

[olddav]

It has a varmint contour barrel and it never became hot, it barely got warm.