Help me look for pressure signs (7mm-08)

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Newtosavage

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I'm not nearly as experienced a handloader as many here are, so I would appreciate more sets of eyes looking over my work as I come up with loads for my Tikka 7mm-08. I bought this rifle to handle the "heavy" bullets, as my Stevens 11.5" twist already does a fine job up to 139 grains (but no mas!). My goal is 160 grain Accubonds at 2600-2700 fps. and 139 SST/Interbonds at 2900.

First, the four tests...

test loads all.JPG
 
Next, here we have 120 grain Sierra Pro Hunters (not a heavy bullet, I realize) over 42, 43 and 44 grains of H4895. Max Hodgdon load is 43.7 grains.

test loads 42-44g h4895 120 sph.JPG
 
2nd up are 139 grain SST's with 41, 42 and 43 grains of H4895. Chrono was 2861-2930 fps., and max Hodgdon load calls for 42.5 grains.

test loads 41-43g h4895 139 sst stevens.JPG
 
3rd up are 160 grain Accubonds over 38, 39 and 40 grains of H4895 for 2560-2650 fps. Max book load is 38.5 grains.

test loads 38-40g h4895 160 NAB.JPG
 
Not seeing any indications. The primers still have their rounded shape on the edges. No bolt imprinting going on either.

Thank you. That's what I'm seeing but I want a 2nd (or 12th) opinion. ;)

Bolt lift was not an issue at all.

With the Tikka, I can seat the Accubonds out to 2.91" and still be .040" off the lands. That's what the 1-hole load was seated at. That gives me a little more room for powder without compressing it so much.
 
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Modern pressure testing has shown that reading pressure signs is not a good indicator of much of anything. By the time the primers are flattening or the bolt lift gets hard the pressure is in the 70,000 psi range. This is why a lot of data has gone down. You show that you are exceeding max loads . The nosler load with h 4350 is also over max. Since there are no pressure signs things should hold together, but, then again maybe not. Be very careful that you do not change anything! A slight change in temperature can give large pressure excursions when running at or near limits. Failures of brass can occur without warning. If you have never seen a case head fail trust me you dont want to. When i started loading a lot of the data was developed with pressure signs and was way too hot. Depending on the rifle much of it would flatten primers.
 
Stringnut, I appreciate your words of caution. Yes, I have seen a case head fail. That is why I'm asking for assistance.
 
Based on my experience with .223, .270, and .30-06, I think your primers are fine, and they indicate that you have room to increase charge slowly.

You should also watch case behavior, MV (if you have a chrony), and published data. You might also consider the effect of ambient temperature.
 
Looking at the primers is always a good thing but not the only thing and of limited value.

Normally signs of problems come in twos.

Even a flat primer alone might be a sign that certain level has been reached but not necessarily that the pressure is close to the maximum for that case
or chamber.
Two factors are important here, one if the size and uniformity of the flash holes and the other the hardness of the primer cup.
Same as the brass, some primers cups are softer than others vs military and some match ones so they show extrusions and flattening much sooner.

So you need to look for stickiness in the bolt, any sighs of splits on the necks and if you have a micrometer measure the rim and base of the cartridge
since any substantial variance will be definitely a sign that the based is stretching and there is no recovery. You might even feel the next priming
lost substantial primer pocket tension that should be lost over time but not that fast. Soft brass is easier to reload but not as elastic as hard brass.

You are doing this right by stopping and even asking because safety is first.

I see a tad of what it seems cratering on the one side that is estrange since is not uniform but might be the pic or my perception but also that would
be fine. Some guns do a bit of cratering like savage and that is not an issue just like a tad flat primer if you are using soft primers.
Confirm the brass you have is rated for nominal pressure and SAAMI should give you a lot of margin but always take the safe approach.

If you want to go closer to SAAMI max I suggest verify your primer is hard as it has been my observation some soft primers flatten way before
they get into the red zone that would be 58-62kpsi give or take. WE actually measured this a few years back with a friend when reloading for f class
and was surprised to see how well below max pressures were even with some flattened soft primers even with properly sized and uniform flash holes.
If you have hard primers and start to flat then that is a different story. Then you might be in the red and most likely you will be feeling other
signs like stickiness, starting extrusions, etc...

So that is why the primers alone are not a good sign. You don't want to be running full pressure as the brass will not last but also you
don't want to be too low for a hot hunting load. Accuracy loads are normally well below max. It is a trade off.

If you use a different primer you have to go back down and start again. the good thing about a harder and hotter primer is that normally the side
effect is more consistent ignition and very important with certain powders and/or cold weather. Also accuracy.
Also if you reload make sure you take note of the temperature because when looking for a hot hunting load you might want to reduce it a tad
for hot weather.

The max load in the manual is a reference and not really accurate since we don't know how that was calculated. (all the variables)
So you can keep going a bit I believe but first sign of any two factors or more like stickiness of the bolt or any initiations of any extrusions then back out.

Did you get your case capacity spreads? this is paramount. If you tells us the primer we might be able to tell you where it rates in terms of hardness.

Good methodology, take comprehensive notes and your micrometer, calipers and good scale are your best friends.
Assume nothing. All we are giving here are references.
 
Thank you. The cratering you see is the shadow in the crater for the most part. I saw it in the pictures but not in real life. Having said that, the shells in #2 (with the SST's) do appear to have "some" flattening and a tiny bit of cratering, moreso than any of the others. I can't detect that in any of the other shells by appearance. The #2's were shot with my Stevens, with the shorter throat, so that may explain it. I am planning to back off in that instance to 41.5 grains, as 2900 fps. is all I need from that bullet, in that gun, to get where I want.

Not sure about case capacity spreads. You'll have to explain that one.

Primers are CCI 200's.

Trying to take good notes so I can get where I want with those 160 Accubonds. If I can get to 2650 safely and accurately, I'm done. If not, I may rechamber to .284 or .280 AI.
 
The 2900 with 139 grain should be attainable. I used to push my 7x57 to 2800 with no issue. As you are getting 2600 with the 160 Accubond is the extra 50 fps that important? Just curious. We are gun people and if you gotta have it then you gotta have it. It doesn't have to be important to any one but you. You know and I know 50 fps doesn't mean anything. I had a high end 22 that should have shot better than half inch at 50 yards. Nothing Itried would get it better than 5/8 . Now no squirrel that ever lived would know the difference, but, I did. Sold it. Read 1st marines post several times if needed. If you are going to push the limits you can't check too many things.
 
Remember that everything is relative. Your chrono might be off up or down that is normal to have a % error with inexpensive machines.
that is why companies are going to better systems including Doppler vs. the light sensor or magnetic no matter how long they are.
2900 is possible but possibly hot from a 22" barrel.
The 162-168's can be pushed to 2750 easily with R17 even a bit more but better come down or use a tad longer coal and longer barrel.
160 accubonds should hit that with R17 as the do in a 22" savage but also check on the brass first in case you need an extra grain or two
so the Winchester has proven to make a difference here.
You will not get the best results with one unique formula and will have to play with what you have.
I think it is pretty darn good where you are so far for a 22" rifle off the shelf.
 
I feel pretty good about the 2900 with the 139's. That load is in the books as far as I'm concerned.

Now on to the 160's. Stringnut, you're absolutely right. That 50 fps. doesn't really matter. I just had a goal to push those 160 Accubonds to 2000 fps. at 400 yards, and that's what it will take. So they are doing 1980 at that distance now. LOL If this is going to be my lightweight elk gun, I want the confidence of seeing those numbers before I pull the trigger.

This evening, my 120 grain Sierra "light" load (2700 fps) did the trick on a big doe at 200 yards. Right on target, 1" exit hole and short and very good blood trail. She went about 30 yards and dropped. I pursued that load for my 7mm-08's in case my daughter or wife or a friend who is just getting started shooting, wants something they can hunt deer with that won't kick real hard. Mission accomplished.

1stmarine, I should have just stared with Win brass as I've always seen the same thing as you - more case capacity than others by a few grains.

Will be picking up some RL-17 before my next trip to the range. So far, I have three very good loads (120/139/160) for my two 7mm-08's and I'm loving this caliber.
 
From my experience, case weight is relative. Deprime, trim, clean, make everything as perfect as you can, then weigh your cases. Some brass is super consistent, some not so much. This is similar to case capacity numbers, only from a different direction...both numbers are telling you how much brass is in your available chamber space. There are 2 schools of thought, and in reality they both have merit. Some like thick brass as it can take a beating and last longer. Some like thinner brass as it can hold more powder. There are tradeoffs in durability and case capacity as thin brass base head separation sooner (theoretically) and thick brass limits your case capacity (by a small amount).

And my most accurate loads which are great hunting loads in the rifles I have built loads for are all right around 3/4 of the way between starting load and max, but I have pushed 130gr .270s well beyond book max to a scary point knowing I was trashing brass after a single shot. Don't go there, it's not worth your best shooting gun becoming a junker when you make a mistake. My rem700 nearly makes me cry knowing I once had a 700 yard 3 inch gun and now I have a 100 yard 3 inch gun. If your itching for the extra oomph go to a long action sooner rather than later. And for Pete's sake if you do push a clambering to it's limits check case length every time so you don't shoot one long and jam it to a point that you have to beat on your rifle with a 4 pound maul and a brass rod to get it apart. I speak from that experience.
 
Exceeding the manuals maximum is not a good idea. IMO. So far you look ok. Brass life may be short, as little as 3 to 5 firing, as the primer pockets expand a little at each firing.

Some high pressure photos here> . https://www.thehighroad.org/index.php?media/users/243winxb.11944/albums

Instead of pushing the 7mm-08 to its maximums, trade up to a magnum. There are more than a few available in 7mm or 30 cal.
 
I don't see any problems with any if those cases either.

As for exceeding the load data by 1/2 grain, while we all know we shouldn't exceed the data passing it by only 1/2 grain will not end the world if you choose to do so. We all know there is a safety margin built into the data. Going to 43.0gr in Post #3 only represents just a hair over 1% which is easily in the safe zone. If course this is only my opinion and not telling anyone they should do it. (I hate having to say that but it's today's world)
 
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And it sounds like he is seating longer than the factory data. Still, be careful exceeding data.

Primers look very good. Primers can lie. Measuring case head expansion is one way to check pressures. Short primer pocket life is a sign. Hard bolt lift is definitely over pressure, but you can be over max without hard bolt lift. Velocity is also another indicator, as there is no free lunch.

Without pressure measuring equipment, we are guessing. It may be an educated guess, but it's still a guess.
 
Exceeding the manuals maximum is not a good idea. IMO. So far you look ok. Brass life may be short, as little as 3 to 5 firing, as the primer pockets expand a little at each firing.

Some high pressure photos here> . https://www.thehighroad.org/index.php?media/users/243winxb.11944/albums

Instead of pushing the 7mm-08 to its maximums, trade up to a magnum. There are more than a few available in 7mm or 30 cal.

Pressure signs many times come in twos and threes. One should always look for all of them and not one in particular.

IMO jumping into a magnum is not necessary in this case. The 7mm/08 is a very efficient case just like the 308 itself, but
with better ballistics.

Books and manuals are not always accurate and why is a good idea to cross reference things.
The maximum is a reference that sometimes is accurate and sometimes is not.
We have plenty of examples of this type of inconsistencies like illustrated below where
maximum values are all over the place. For example why Barnes would put a max load of 44.3gr
of CFE vs. the 43.2gr for a 140gr bullet when we know the barnes bullet leaves less capacity
due to the leadless construction? Anyone who knows CFE knows the high density allows to safely increase
possibly well past the Hodgdon advertised load. So with a 140gr spitzer one could go even higher.
I am not saying Barnes is right on his max load neither but this is to show nobody is right because
you might also use a different brass and possibly play with the COAL. So all this is just a reference
and nothing else. It doesn't really say the max pressure limit that by the way nominally is not even 48,900 CUP
but 52,000 CUP (62K psi). Manuals are a bit arbitrary and books are full of errors and inconsistencies like the Lyman
re-loaders book that is not cheap to buy by the way.

7mm-08

Hodgdon data
upload_2017-12-31_14-26-38.png





upload_2017-12-31_13-29-48.png


BARNES DATA
Case: Remington
Primer: Federal 210
Case Trim: 2.025”
Barrel Length: 24”
Twist Rate: 1:9.5”
Barrel: Bartlein

upload_2017-12-31_13-37-27.png


upload_2017-12-31_13-33-13.png



W/o knowing all the other variables is hard to say how it was determined and for that reason there are maximum loads in many calibers that
are well bellow the maximum for that cartridge. When you reload you see it, f you run your loads with Quick load you see it.
you buy commercial ammo that exceeds the maximum of any of their advertised loads for the same barrel and they do it safely so you see it there too.

Hodgdon for example has a lot of loads for many calibers below actual maximum given modern brass, bullets and the capability to adjust coal.

This doesn't mean one should ignore maximum advertised loads and treat with respect and attention to detail every aspect of the reloading
process.

Again,
1- know your brass - Winchester 308 formed might give you up to 2 extra grains vs. other casings. Get the spreads for each brass make and year/batch.
2- know your chamber - make a dummy round for every bullet to understand max coal given by the freebore and also adjust for jump/COAL x distance from the lands.
3- now your bore - For example a 3R bore offers less pressure on the bearing surface than a typical 6R enfield.
4- know your primers and powders. Choose wisely and stick to the method.
5- measure everything, assume nothing. Micrometers give precise spreads of brass changes at the web that is a consequence of high pressure.
6- Cross check data and converge the data and also QL is a great predictor for loads but even this is not 100% accurate and might need tuning depending on the variables you have.

Happy new year everyone!
 
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Instead of pushing the 7mm-08 to its maximums, trade up to a magnum. There are more than a few available in 7mm or 30 cal.

I want a lightweight, 400-yard elk gun. I don't feel I need a 7mm mag for that.
Frankly, the 139 grain load - that is within book max. - is more than sufficient based on all the research I've done. My son will be toting that round in his 7mm-08. But I'd like to lob 160's if I can, and still comfortably get them to 2000 fps. at 400 yards. If I can't, I'll back off to 150's, 140's or 139's and go hunt. I'm not going to overthink this.
 
And it sounds like he is seating longer than the factory data. Still, be careful exceeding data.

Those 160 Accubonds in my Tikka allow me 2.95" to the lands. I seated the rounds in the test to 2.91" or 0.40" off the lands and single loaded them (for now).
 
That accubond load looks just right.
I use RL17 which is essentially identical to the H4350.
I'd load up and go hunting. I use 150gr BT over same charge, but my rifle has a minimum dimensions barrel.
I'd use that AB load on anything in NA save the great bears.

Who's to say some particular factory load isn't marginally over max for your rifle?

I've got some PMC FACTORY 139's that chrono's over 3,000fps from my 20"Rem. M7 barrel. They crater primers and burnish the caseheads. Much more pressure than your loads. Resized cases reloaded w/o neck turning won't even chamber in my rifle...

Remember, max loads are "suggestions, and recommendations", based on observations with stated particular components and equipment. Your results may vary.
Your gun, your components, your CHOICE.
AINT FREEDOM GREAT!!!
If you're happy, I'm happy!
 
Who's to say some particular factory load isn't marginally over max for your rifle?

When I had my 7x57 Ruger 77, I could never find a load to equal the factory Remington 140's. That factory load was hotter than anything I was willing to load.
 
Another trip to the range this morning. Bumping up charges with H4350 and Big Game under 160-grain Partitions.

Would love to hear your thoughts on the following images.

First, we'll start with a "reference load" - a mild starting load of 44 grains of Big Game under 139-grain SST's.

starting load 44g BG 139 sst.JPG
 
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