I am continuing in load development for a 280 AI, and with 140 gr AB's had slight sticky bolt at 64 grains of H 7828 SSC (.5 grain below book max) so I figured I would call 63 grains max with that bullet and call it good. I was also trying the same charge weights with a 140gr TSX.

At 64 grains with the AB's 3 of the five showed no pressure signs at all, and 2 (no 2 and 4 fired) showed a very slight sticky bolt. I went to the TSX's and at 63 grains, no issues, very good accuracy--same OAL as the AB's BTW, but at 64.0--WOW--could NOT open the bolt!

Let the rifle sit for about 10 minutes, it was not real hot, had let it cool in between firing the two loads, fired say 3 or so in pretty close succession, then waited 15 mins or so between the next groups of firings--but after the ten minutebreak, I was able to pull the bolt back--with all my strength--and the case ejected so hard that it put a whelt on my head! I couldn't believe a case could be ejected that hard--I would have lost a bet if someone had bet me they could eject a case hard enough to put a whelt on my head!

The primer had blown on the case, and it had a bright ejector mark on it, but otherwise looked OK...I am wondering if the TSX's (whose ogive is actually shorter than the AB's, so they were jumping like 20 thou to the lands) are harder to engrave and just spiked pressure at the 64 grain mark??? A friend of mine that ran a rifle company a while back, was a big believer that TSX's could spike pressures.....I am just wondering what to do next, Have thought about just calling a lower number max for this rig, and trying a different powder, plus maybe seating the bullets a little deeper to give more jump???

Interested in ya'lls thoughts, thanks.

When the Barnes sold copper bullets first came out they produced high pressure and lots of fouling compared to standart lead core types. Then 3 grooves were cut into them to eliminate these problems. All copper bullets will make more pressure than lead core bullets. "Barnes suggests seating TSX, MRX and other X-style bullets .030 to .070 inch from the lands. Begin by seating the bullet .050-inch from the lands" A blown primer and the bright ring from the ejector are sure signs of high pressure, along with the hard to open bolt.

FWIW, you are cooking way beyond reasonable pressure limits. When you load up to sticky lift pressures, you are really pushing the envelope.

Another thing to consider is how long the loaded case sat in the hot or even warm chamber before you pulled the trigger or how long the loaded ammo sat in the sun. That will make borderline loads go over the line. Best to consider all of these things when in development.

quote:

Originally posted by Fish30114:
I am just wondering what to do next...trying a different powder, plus maybe seating the bullets a little deeper to give more jump???

Yes

Are you using Nosler brand 280AI brass?

Been there; done that.

Published max loads have nothing to do with what your rifle will handle. There are just too many variables. Reloading manuals are simply reports stating that "this is what we got when we used these components and charge weights". 64gr is way too hot for your rifle. IMHO, 7828 isn't going to be the best powder for you, anyway.

At least their are published loads for the 280AI. I used to work up loads for wildcats until I blew a primer, and then back off 1 gr. The last time I experienced a blown primer was several years ago. The rifle seemed to handle the other shots fired with the same load without any problems. I wound up with a blown extractor and a marred bolt face. That was the last time for me. When you get stiff bolt lift and see markings on the case head, you are probably over 72,000psi.

Nowadays, I work up in smaller increments as I approach the upper end loads and only look for the most accurate load. I move up to a larger case if I desire more oomph. You are burning as much powder in your 280AI as I did in my 7mmRemMag.

My favorite 140gr load for my 7mmRemMag was always 65.0gr of IMR4831. There are powders available today that can produce more velocity, but not better accuracy (in my rifle).

If I only want to burn 50gr of powder, I'll use my 7-08AI. If I'm going to burn 64gr of powder in a 7mm, it will be out of a 7mmRemMag.

quote:

Originally posted by SST:
Been there; done that.

Published max loads have nothing to do with what your rifle will handle. There are just too many variables. Reloading manuals are simply reports stating that "this is what we got when we used these components and charge weights". 64gr is way too hot for your rifle. IMHO, 7828 isn't going to be the best powder for you, anyway.

At least their are published loads for the 280AI. I used to work up loads for wildcats until I blew a primer, and then back off 1 gr. The last time I experienced a blown primer was several years ago. The rifle seemed to handle the other shots fired with the same load without any problems. I wound up with a blown extractor and a marred bolt face. That was the last time for me. When you get stiff bolt lift and see markings on the case head, you are probably over 72,000psi.

Nowadays, I work up in smaller increments as I approach the upper end loads and only look for the most accurate load. I move up to a larger case if I desire more oomph. You are burning as much powder in your 280AI as I did in my 7mmRemMag.

My favorite 140gr load for my 7mmRemMag was always 65.0gr of IMR4831. There are powders available today that can produce more velocity, but not better accuracy (in my rifle).

If I only want to burn 50gr of powder, I'll use my 7-08AI. If I'm going to burn 64gr of powder in a 7mm, it will be out of a 7mmRemMag.

Exactly! You also can NOT substitute ABrnes for cup/core bullets w/ the same powder charge, pressure wil lbe higher, even w/ the newer TSX designs. Mono metals develope more pressure than lead core bullets. Nosler partitions develope more pressure than std cup/core bullets.

Fish, in my 280 AI w/24" barrel I load the barnes 140 TTSX to 64 grains and get 3150 and 150 TTSX to 62 grains and see 3050, but I'm loading RL22. Accuracy is great at less than 3/4" with both.(nosler brass) Maybe try RL 22?

quote:

Originally posted by handwerk:
Fish, in my 280 AI w/24" barrel I load the barnes 140 TTSX to 64 grains and get 3150 and 150 TTSX to 62 grains and see 3050, but I'm loading RL22. Accuracy is great at less than 3/4" with both.(nosler brass) Maybe try RL 22?

I find IMR7828 a bit slower than RL22 in my 280 or 7mags. Caution, every rifle is diff.

Guys, thanks for the intel.
Onefunzr, I am using Nosler brass.

SST, that is helpful intel, in NO way am I a push the envelope kind of guy, except inadvertently--like in this case! I will definitely try some different powder, and back down on the load, thinking I was over 70K PSI scares the shit out of me...

I am an accuracy guy FIRST, of course I want decent velocity, but I frankly was trying the 280 AI looking for excellent accuracy, and hoping to run 140's a little faster than my 270's do, and maybe shoot 160's at around 2800.

I really thought having 20thou of jump with the TSX would be enough, but I'm definitely going to seat them deeper to get me around 50thou from now on, and I think I'll call max with 7828 SSC 62 grains in this rifle--do ya'll think that is backing off enough from the blown primer experience at 64?

I also wonder if any damage may have been caused to my rifle? Everything looks fine with the borescope, and the bolt face looks just like it did before I shot it this trip--I've read about cumulative metal fatigue, just wonder about ya'lls thoughts on the couple of obviously high pressure rounds going through this rig--It's a Cooper Model 52 and the action is pretty stout IMO, and the bolt is definitely so, plenty of meat to it so to speak....

I'll think about RE 22 and also look at some of the V V powders I have and see what they should give.

I was semi-surprised that I didn't flinch when I shot my 204 Ruger after giving myself the welt on my head...and then it quit igniting the cartridges after the 3rd round....darn Cooper guys left the screw out of the firing pin/bolt assembly/cocking piece when they worked on my bolt--but that's another story

High pressure on some and not on others could mean a tight neck condition. Make sure you loaded round neck diameter is not to large for you chamber. After firing the brass should be about .002" larger in diameter than the loaded rounds.You dont want more of theses.

If you can slip a bullet into the neck of a fired case, you're good to go.