Win 284 - can't reach 2800 with H4831SC without ejector marks

[Alex Wheeler]

Yes, your see my point now. Once the brass becomes "plastic" from compressive force its will flow like you stated, however the fact theres 60k inside the pocket means it will flow out ward. Two forces both working to expand the pocket. I stand by my stance that a 284 pocket will loosen faster than a 7-08 because its under more stresses.

 

[dskogman]

Just to be clear, the primer pockets expand when you are significantly over pressure. Keep it reasonable and (<2900+ fps) they are fine. I've got some over 8 firings (Norma)

 

[Larryh128]

Yes, your see my point now. Once the brass becomes "plastic" from compressive force its will flow like you stated, however the fact theres 60k inside the pocket means it will flow out ward. Two forces both working to expand the pocket. I stand by my stance that a 284 pocket will loosen faster than a 7-08 because its under more stresses.

Absolutely correct statement.

 

[ImBIllT]

Yes, your see my point now. Once the brass becomes "plastic" from compressive force its will flow like you stated, however the fact theres 60k inside the pocket means it will flow out ward. Two forces both working to expand the pocket. I stand by my stance that a 284 pocket will loosen faster than a 7-08 because its under more stresses.

The force pressing the brass against the bolt face will also push inward shrinking the primer pocket. The reason it expands is due to the pressure from inside the pocket, not due to brass being pressed against the bolt face. If anything, that force reduces primer pocket expansion. That's how primer pocket swagging works.

 

[284winner]

The force pressing the brass against the bolt face will also push inward shrinking the primer pocket. The reason it expands is due to the pressure from inside the pocket, not due to brass being pressed against the bolt face. If anything, that force reduces primer pocket expansion. That's how primer pocket swagging works.

All I need to know is when will my head start feeling better after reading all that rocket science. Holy crap. I just eeny meeny minny moed my brass and I'll just stick with the 284 and deal with loose primer pockets eventually. Brass is still easier to buy than trying to read that again. You guys study waaaay tooo much. No offense meant.

 

[284winner]

LOL, Im a high school drop out!

Well there you go...high school is way over rated. Wish I could run into one of your high school teachers.

 

[Hermantk]

This 7mm Win .284 is new to me, I have been shooting all varieties of 6mm with some success, but to be competitive at long range I feel I really need to get on the 7mm bandwagon.

I have a Krieger 4 groove 32" F-Class gun...
180 Berger Hybrid, jumping .015, CCI BR2 primers, COAL is 3.247.

Chambering has neck at .315, loaded round is .3105 (turned necks), and fired casing are .313.
Loaded with .002 neck tension, and bullets are not hard to seat (30psi with 21st century arbor press with gauge)

I can't get to the 2800 fps+ node.

The barrel now has 200 rounds on it and I thought it might speed up, but it really hasn't

54.6 gr H4831SC is almost there at 2795fps, but I get slight ejector marks. Over 25 rounds, I get 2795 fps, 24 ES, 8 SD, shoots about .33 MOA at 300... good, but not great like my 6BRAI . The ejector marks show up at the end of the 20 shot string.

With H4381SC, Quickload shows 53K psi with max of 63K, so I should I was ok, but the ejector marks are telling me otherwise.

So I thought about trying H4350, thinking that 51.5 was the target, I started "low" at 50.0/50.4/50.8/51.2, but 50.0 gr gave me 2790 and slight ejector marks, I shot all 5 that I had loaded, and put 1 of the 50.4 down the tube (2825fs and hard ejector mark, hard bolt lift) and pulled the rest of them apart. Using, quickload and calibrating the 50.0 gr H4350 to 2790 fps shows 58K psi... too much, and explains the ejector marks)

Do I just have a slow barrel?
Should I try a different primer? I have some CCI 200, and Winchester LR....
Different Powder?

I'm open to any and all suggestions.


- pat

have you considered that it might be an issue with your action or brass? I am running 180 hybrids (CCI BR2 and 54.7 gr of 4831SC at 2850fps through an 8 twist and I am now at my 4th reload with absolutely no marks of any kind. My action is a BAT 3L and my brass is Lapua

 

[Ares]

So much theory about rebated rims being a big weakness, and giving loose primer pockets.
It has to do with the whole construction, and dimension of the case, thickness of case head, case wall thickness etc, not simply the rebated rim.

Anyone who has abused RWS 8x68s brass to any extent, would know what i mean. One of the strongest rifle cases you will find, and it has a rebated rim

 

[GSPV]

OP: If I read your initial post correctly, you have 1 thou per side neck clearance. You’ll want more in your 284 for best accuracy. Might or might not have anything to do with your pressure situation. Try 2 to 2.5 per side.

 

[dougridgeore]

Pat. Regarding your new 284 Winchester:

We shoot together alot, you know who I am.... just a thought....one time someone needs to try those Hornady 162 ELD-M’s with 51 grains of H-4350 and a 9 twist recently I loaded up 50 rounds and tried them at 1000 yards I shot about 15 shots all in the x and ten ring then for the rest of the box I had a bunch of new shooter on my gun with me making wind calls....I think we only shot about 4 rounds in the 9 ring. Out of 50 shots at 1000 yards. Those cheap bullets shoot real good.

several of the other Portland area shooter have shot them at 600 yards to great success just once a high level shooter like yourself should try them at 1000 in a big match.

I will probably never do it heck they are Hornady’s.....fact is I would not even attach my name to this post. Just saying they shoot and with less pressure than the 180’s

btw...I pulled them right out of the box

 

[jr600yd]

Many 284’s preform best with .004 or more neck clearance.

 

[pat fulghum]

The original thread is over a year old...

The barrel had a “tight spot” which caused pressure.

 

[338 dude]

This 7mm Win .284 is new to me, I have been shooting all varieties of 6mm with some success, but to be competitive at long range I feel I really need to get on the 7mm bandwagon.

I have a Krieger 4 groove 32" F-Class gun...
180 Berger Hybrid, jumping .015, CCI BR2 primers, COAL is 3.247.

Chambering has neck at .315, loaded round is .3105 (turned necks), and fired casing are .313.
Loaded with .002 neck tension, and bullets are not hard to seat (30psi with 21st century arbor press with gauge)

I can't get to the 2800 fps+ node.

The barrel now has 200 rounds on it and I thought it might speed up, but it really hasn't

54.6 gr H4831SC is almost there at 2795fps, but I get slight ejector marks. Over 25 rounds, I get 2795 fps, 24 ES, 8 SD, shoots about .33 MOA at 300... good, but not great like my 6BRAI . The ejector marks show up at the end of the 20 shot string.

With H4381SC, Quickload shows 53K psi with max of 63K, so I should I was ok, but the ejector marks are telling me otherwise.

So I thought about trying H4350, thinking that 51.5 was the target, I started "low" at 50.0/50.4/50.8/51.2, but 50.0 gr gave me 2790 and slight ejector marks, I shot all 5 that I had loaded, and put 1 of the 50.4 down the tube (2825fs and hard ejector mark, hard bolt lift) and pulled the rest of them apart. Using, quickload and calibrating the 50.0 gr H4350 to 2790 fps shows 58K psi... too much, and explains the ejector marks)

Do I just have a slow barrel?
Should I try a different primer? I have some CCI 200, and Winchester LR....
Different Powder?

I'm open to any and all suggestions.


- pat

With a barrel that long you need a slower powder and you will get higher velocity

 

[FrankG]

Do you know the exact bore and groove size? Not just .277x.284....you need to know to the 4th decimal place.

If the bore/groove is tight that could be part of your frustration.

That being said if it's shooting great at 2775fps. then run it there.

 

[284winner]

This 7mm Win .284 is new to me, I have been shooting all varieties of 6mm with some success, but to be competitive at long range I feel I really need to get on the 7mm bandwagon.

I have a Krieger 4 groove 32" F-Class gun...
180 Berger Hybrid, jumping .015, CCI BR2 primers, COAL is 3.247.

Chambering has neck at .315, loaded round is .3105 (turned necks), and fired casing are .313.
Loaded with .002 neck tension, and bullets are not hard to seat (30psi with 21st century arbor press with gauge)

I can't get to the 2800 fps+ node.

The barrel now has 200 rounds on it and I thought it might speed up, but it really hasn't

54.6 gr H4831SC is almost there at 2795fps, but I get slight ejector marks. Over 25 rounds, I get 2795 fps, 24 ES, 8 SD, shoots about .33 MOA at 300... good, but not great like my 6BRAI . The ejector marks show up at the end of the 20 shot string.

With H4381SC, Quickload shows 53K psi with max of 63K, so I should I was ok, but the ejector marks are telling me otherwise.

So I thought about trying H4350, thinking that 51.5 was the target, I started "low" at 50.0/50.4/50.8/51.2, but 50.0 gr gave me 2790 and slight ejector marks, I shot all 5 that I had loaded, and put 1 of the 50.4 down the tube (2825fs and hard ejector mark, hard bolt lift) and pulled the rest of them apart. Using, quickload and calibrating the 50.0 gr H4350 to 2790 fps shows 58K psi... too much, and explains the ejector marks)

Do I just have a slow barrel?
Should I try a different primer? I have some CCI 200, and Winchester LR....
Different Powder?

I'm open to any and all suggestions.


- pat

Give Reloader 17 a shot. I'm surprised how well it shoots in both my rifles.

 

[Borisserge]

Maybe an (expensive) cheap option is to try VV N165 for a slow burning powder that gives decent fill and speed, and a decent SD potential.
My first time out with my 284w with 180h and had an SD of 5.7 (at 1000 yards) and accuracy I am happy with after the briefest of load development.

 

[davidjoe]

So much theory about rebated rims being a big weakness, and giving loose primer pockets.
It has to do with the whole construction, and dimension of the case, thickness of case head, case wall thickness etc, not simply the rebated rim.

Anyone who has abused RWS 8x68s brass to any extent, would know what i mean. One of the strongest rifle cases you will find, and it has a rebated rim

Although the rest of the web may be thick, the rebated rim along with the ejector groove surround enough of the primer pocket to define its resistance to being crushed and therefore spreading open.

Relative to a .308 head, I believe .284 Win is nominally the same, but factor in that TR shooters use small primer pockets, and the TR round is actually stronger at the weak spot than the prevalent Open round. A small primer .284 case would find a market. Like Lapua brass with a factory 7mm neck.

 

[davidjoe]

Re-examining my stance, the case is probably better represented as a piston than a pressure vessel. In that case, the larger case body diameter would result in more thrust against the bolt face. The smaller case head would thus be subjected to a greater stress. However, that stress would push the brass INWARD toward the primer pocket, and outward as well. The swelling of the primer pocket is still due to pressure from inside the primer pocket, and that pressure is equal to the pressure inside the rest of the case. I stand by my stance that the swelling of the primer pocket in .284 brass would be identical to or possibly less than that of a 7-08 exposed to the same pressure. Leaving the case head at magnum diameter would offer increased support, but the decreased support from the rebated rim simply puts it in the same class as the 7-08.

Neither a pressure vessel nor a piston accounts for the sharp rearward recoil thrust of the rifle. In addition to the significant internal pressure, I’ve always assumed that recoil force is transmitted to the casehead, then to the bolt lugs, receiver lugs, then stock, and if so, the casehead necessarily transmitted that impulse to the bolt, and it smashes itself in that process. A 7-08 would not recoil as much, and therefore pressure on its casehead would not be expected to be as high. Since it’s the same size, but experiences less recoil impulse, it deforms less. Pockets that loosen after 15 firings probably succumb to this force while new brass that drops its primer inside the chamber on the first over-pressured shot isn’t doing so because of recoil.

 

[davidjoe]

Trying to envision this primer pocket compression in a vice or slow motion, and only columnar outward bulging from pressure on the casehead that does not squeeze it inward seems plausible. The path of least resistance for the displaced metal to flow is where there is not metal competing to occupy the same space. That’s the outer diameter where it can move outward without being laterally compressed by adjacent material. This is consistent with the effects of a column under tension and compression. Tightening screws causes them to become slightly longer and thinner. Should you bore a hole through one, the hole will also become longer and thinner upon tightening. Compressing a screw (such as turning it to and beyond the immovable stop of a blind hole) would have the opposite effect of tightening it. A compressed primer pocket is analogous to a compressed screw.

 

[No i deer]

Is this new brass? The increased headspace does some funny things. I don't get ejector marks, but I don't have an ejector either.

I also noticed that your OAL is a little shorter than I would have expected. What is the freebore?

Somebody told me the witness marks can come from new brass with a little too much headspace where the case get blow back against the ejector