How close to max powder do you typically find good loads?

[SGK]

I use a ladder test and read the paper.

Of course, although I intend to focus on readings from a very good chronometer for muzzle velocity uniformity - powder charge node - and dispersion on paper for seating depth node.

My question was a different one - and borne from a certain trepidation from my first time climbing the powder ladder and being (very) wary of going too far. Hopefully I will know early indications of excess pressure when I see them and before I get to bad excess pressure. I'm scouring through all the video and images I can find between now and heading back to the range. Obvious excess pressure is, well, obvious. I'm less sure in that (highly subjective?) grey area where one crosses from 'comfortable' to 'early indications of excess pressure'. I will report back.

 

[Homerange]

Of course, although I intend to focus on readings from a very good chronometer for muzzle velocity uniformity - powder charge node - and dispersion on paper for seating depth node.

You certainly don't need to go overboard chasing 'quality' cronies.
We put 2 cheap Chrony's back to back and they agreed to within a couple of fps.
When the one I have reported for a load I tried only 6fps ES it confirmed that even the cheap ones are plenty good enough for the average reloader.

More than anything I use it as a sanity check that velocities are 'near enough' to the manual data I'm working from and then to seek that sometimes elusive low ES load.

 

[Richard Coody]

hard to say what is max reading books. barrels are quite different. if you know what to look for your barrel will tell you what is max. i like to find max with any barrel/powder/bullet combination i use. then i back off to the first node i find for brass life.

 

[SGK]

I have a couple already. I have the Magnetospeed which is "ok". It's average is reasonably accurate but its shot-to-shot random error rate is too high IMO. The best thing out there for measuring shot-to-shot velocity variance is the Two Box Chrono. I don't consider it terribly expensive. I'm happy to use the Magnetospeed (or other means) when I want to know actual/absolute muzzle velocity - as an input to predicting ballistic trajectory (later proved at the range) - but for load development where I want to observe velocity SD without readings being clouded by chrono random error I will rely on the Two Box. There I care less about whether the average recording is accurate - and hence don't need to fuss with chrono to target alignment etc. I just care about getting very accurate SD numbers. (ES is a relatively useless statistic; interesting to know, but not as valuable as SD as far as understanding underlying behaviour.)

Sure, today I am loading for a Blaser sporting rifle. But I'm building a 6mm around a Defiance action, Bartlein barrel etc - waiting forever for parts...

 

[rammac]

I and other military team members have pulled bullets from M80 ammo with 41 grains of IMR4475 powder then seated Sierra 168's or arsenal 173 grain match bullets in them. I was issued a thousand or more from the USN Match Conditioning Unit in San Diego. LC65 lot 12638 was a favorite for use in our Garands;
View attachment 1079155

Numerous on line sources have listed the same case (stannic stained light blue), primer and powder charge with the 173 grain FMJBT bullet for M60 7,62 NATO proof loads. It was often called Mexican match ammo.

PS: IMR4475 was replaced with W846 when Winchester took over ops at Lake City arsenal. Don't think it was ever rebulleted for match use.

This doesn't prove that the pressures ran up to 81,000 PSI (as per your previous post).

I know what mexican match was and it never reached that kind of pressure.

Mexican Match was made from M80 ammo which was used in the M14 (.308/ 7.62x51mm) not the Garand (unless your Garand was rechambered for the 7.62x51mm)

IMR 4475 was/is a short grained version of IMR 3031 and it burns similarly, as such, 41 grains would never produce 81,000 PSI, even under a 175 grain SMK bullet.

M118 LR (for the M14 rifle in 7.62x51mm) is known to produce some pretty high pressures, some in the 70,000 PSI range (more if the ambient temperatures are over 90 degrees), if I recall correctly.

Seeing as how the Army’s maximum allowable pressure for its .30-06 ammunition (M2 Ball) in the M1 Garand is 50,000psi, with a maximum proof test load pressure set at 67,500psi I don't really believe that any ammo that would produce over 68,000 PSI would be safe in the Garand. Military shooting teams will shoot their rifles out without regard to wear because they have a big budget and can rebuild or replace their rifles as neccessary, I don't have that luxury so I will never push my rifles to point of failure like they do.

 

[rammac]

My experience has been that most often my highest accuracy node is usually just about 1 grain under the recommended book max. I usually find another accuracy node just about 1 grain over the SAAMI max pressure recommendation (estimated by QuickLoad software). Firearms are typically proof tested at very high pressures, usually something like 80,000 PSI or more for rifles, so if you exceed the SAAMI max pressure recommendation once in a while you shouldn't do immediate harm to your rifle but I wouldn't recommend doing it regularly because it just accelerates the wear due to stress and strain. Firearms are designed to withstand up to a maximum amount of pressure and the metal will recover from the stress if you don't exceed that limit. If you do exceed that limit then the metal will slowly expand beyond it's original dimensions and it will eventually fail due to cracking, maybe catastrophically.

 

[Bart B.]

Seeing as how the Army’s maximum allowable pressure for its .30-06 ammunition (M2 Ball) in the M1 Garand is 50,000psi, with a maximum proof test load pressure set at 67,500psi I don't really believe that any ammo that would produce over 68,000 PSI would be safe in the Garand.

Those are copper crusher gauge units of pressure "cup" incorrectly stated as pounds per square inch. (I thought we all knew that so please excuse my ignorance.)

The USN Garands were rebarreled to 7.62 NATO.

IMR 4475 was/is a short grained version of IMR 3031 and it burns similarly, as such, 41 grains would will produce 81,000 PSI, even under a 175 grain SMK bullet, in a piezeo transducer pressure system.

Check SAAMI standard and proof pressure specs for both 308 and 30-06 with cup and psi systems. Some are almost 90,000 psi.

Discussing Mexican match ammo with other service teams at the Interservice and National matches, any arsenal ammo rebulleted was so nicknamed, including M118 with Sierra 168's and 180's.

 

[Homerange]

I have a couple already. I have the Magnetospeed which is "ok". It's average is reasonably accurate but its shot-to-shot random error rate is too high IMO. The best thing out there for measuring shot-to-shot velocity variance is the Two Box Chrono. I don't consider it terribly expensive. I'm happy to use the Magnetospeed (or other means) when I want to know actual/absolute muzzle velocity - as an input to predicting ballistic trajectory (later proved at the range) - but for load development where I want to observe velocity SD without readings being clouded by chrono random error I will rely on the Two Box. There I care less about whether the average recording is accurate - and hence don't need to fuss with chrono to target alignment etc. I just care about getting very accurate SD numbers. (ES is a relatively useless statistic; interesting to know, but not as valuable as SD as far as understanding underlying behaviour.)

And that's the thing, for a truly long range rifle ballistic performance has to be proven. The guys that come here take real care doing that resulting in minor tweaks to the BC inputs into their trajectory programs in order to get better than 1" vertical accuracy predictions at whatever range they're shooting......how else do you hit a prone rabbit @ 800 yds ?

Sure, today I am loading for a Blaser sporting rifle. But I'm building a 6mm around a Defiance action, Bartlein barrel etc - waiting forever for parts...

6mm what ?

 

[SGK]

Speaking of velocities... I find it interesting that my HPS Target Rifles Ltd 'factory ammo' shoots an average muzzle velocity of about 2686 fps (the last string I recorded with my Magnetospeed). This is ammo made to order from my 2x fired cases but not in any way tuned for my individual rifle (other than telling them the brand and calibre). The bullets (as mentioned before) are Sierra Matchking 168 grain. I don't have the powder they used (but will try to find out). 2686 fps is higher than the 2600 under which most max loads are listed for Hornady bullets in this weight class (22" barrel). It is also right up there with the max velocities listed for Berger 168 gr bullets (23" barrel). (I note their max charge for Varget is 42.5 grains.) How would you describe that sort of average velocity for this calibre? Is it getting into 'hot' territory?

(Blaser standard barrels are 580mm = 22.8".)

 

[SGK]

6mm what ?

After much deliberation I went with 6mm Creedmoor. Not because I am "Creed fanboy" but because one of my prerequisites - or you could view it as a constraint - was that I still wanted flexibility from the rifle and that included reliable magazine feeding. (I want the flexibility to take it into the field rather than just target.) Also, I wasn't keen on having to form brass and the availability of Lapua brass was another key factor. I discussed pretty much the full range of 6mm cases with Dana English and that's where we came out.

 

[Homerange]

Speaking of velocities... I find it interesting that my HPS Target Rifles Ltd 'factory ammo' shoots an average muzzle velocity of about 2686 fps (the last string I recorded with my Magnetospeed). This is ammo made to order from my 2x fired cases but not in any way tuned for my individual rifle (other than telling them the brand and calibre). The bullets (as mentioned before) are Sierra Matchking 168 grain. I don't have the powder they used (but will try to find out). 2686 fps is higher than the 2600 under which most max loads are listed for Hornady bullets in this weight class (22" barrel). It is also right up there with the max velocities listed for Berger 168 gr bullets (23" barrel). (I note their max charge for Varget is 42.5 grains.) How would you describe that sort of average velocity for this calibre? Is it getting into 'hot' territory?

(Blaser standard barrels are 580mm = 22.8".)

Not according to the ADI site data....they make Varget:
http://www.adi-powders.com.au/rifle/308-winchester

 

[Homerange]

After much deliberation I went with 6mm Creedmoor. Not because I am "Creed fanboy" but because one of my prerequisites - or you could view it as a constraint - was that I still wanted flexibility from the rifle and that included reliable magazine feeding. (I want the flexibility to take it into the field rather than just target.) Also, I wasn't keen on having to form brass and the availability of Lapua brass was another key factor. I discussed pretty much the full range of 6mm cases with Dana English and that's where we came out.

Certainly has the advantage of being short actioned I guess. One of the best I've seen here is a custom 6mm Rem built on what was a 22.250 Tikka. New bolt stop, mag and barrel. Shoots like a laser.

 

[Bart B.]

How would you describe that sort of average velocity for this calibre? Is it getting into 'hot' territory?

If everyone used the same test barrel, pressure measuring stuff and chronograph setup, data would be more realistic and comparable.

 

[BCBRAD]

If powder is compatible with components and on a node, 57-60,000 psi seems the best.
Velocity is what it is.

 

[onelastshot]

From my experience, it really depends on cartridge and individual barrel. All rifles are different and reach optimum accuracy at different levels. My 22-250AI loves Rl17 on the hot side. My 7x57 Ruger No.1 obtains optimum accuracy at mid level loads. I've tried to boost velocity and end up with unwanted spreads. In short, the only true results will be by conducting your own ladder tests and see what results you get.

 

[corsair4360]

I posted earlier in this forum. What I did not say was that the loads I listed are all over the map, some are maximum loads, others are low end of range loads, others... in between. The 6xc loads are maximum, but they shoot great. Each rifle/barrel and cartridge combination are unique.

 

[SGK]

FWIW I heard back from HPS. The load for my existing 308 ammo supplied by them is N540 at the max load of 44.5 grains. Interestingly they said it is now next to impossible to source Hogdon powders in Europe due to REACH Compliance/Registration requirements.

(Anyone importing more than 1 tonne of chemicals into Europe needs to submit data to the European Chemicals Agency.)

 

[Flouncer]

Contrary to others advice I research the loading books to find max listed loads as compressed and start a little below to check there's no pressure surprises and try to finish development with close to 100% case fill.

In general it's my understanding that a high % case fill offers the most consistent ES.
Please enlighten me if I have that wrong.

Slight off topic, but here it is again. "Case Capacity" I can fill a case with powder till it's full. As in common english where no more will fit. Say 60g of ABC123. That's not what you mean here. You mean 56g of ABC123 which is where the bullet is now starting to compress the powder. So there is more wiggle there yet, the full 1.0g of powder that it takes to start the compression, and the difference between the geometry of a boat tail and a flat base of exactly the same mass. The boat tail will start to compress, then some powder will crunch up the sides (?). Can someone please explain exactly what is meant by this, in a useable format to a cautious weekend warrior reloadeer for hunting and loading references, Hodgden, Alliant, Nosler, Berger that list "104% of "capacity ? ? ? - thanks

Edit: found this wow !! http://forum.accurateshooter.com/threads/close-call-with-nosler-243-load-data.3961606/page-3

 

[Homerange]

@Flouncer
I'm unsure of what is officially 100% case fill, probably where there is zero compression of the powder so your example of 104% would indicate some powder compression. Those that like to work with compressed loads would see 104% as little problem and those that want to go to a higher % fill would use a drop tube funnel to help pack more into the case.
None of this a problem providing we all play safe with our loads......there's enough warning signs for the observant reloader to warn them when reaching excessive levels.......stiff bolt lift, ejector marks on the case head, leaking or blown primers.....etc.

Be careful out there !

 

[Don_Parsons]

308 winchester, 44.2gr of Varget with 168gr bullets Lapua brass seated 2.810,,, CCI 450 SM primers

It's one of my sweet hunting loads