Suggested starting load?

S

Stats Shooter

New member
I have a question for the group. What do y'all do when there is a huge spread or difference in suggested starting load and max load?

I am making some match grade .308: federal brass, CCi Br2 primers, 175 gr SMK'S, IMR 4064.

The thing is, my Sierra manual suggests a 38 great starting load and 42 Grain max. Meanwhile hodgdon suggests starting at 41.5 and the max is 45.6(compressed)....That is a big difference!
I pulled some Federal GMM a few weeks back and they used 41 graines of IMR 4064 in the 175 Grain load. Now I know the factory powder is a bit different than the commercial grade stuff. But I can't imagine it is that much different.

In any case, I was just wondering what you guys do in this case? I'm thinking of starting at 40 and laddering up in 1/2 grain jumps and then tweaking the load in 1/10 Grain increments around the accuracy node.
 
I first do some research
Sierra 175gr MK ( a very good bullet )
not Sierra175 TMK, the TMK is a completely different bullet

Loading manual "accuracy load" from 2 to 3
manuals of similar weight bullets

check to see what others are using
( in this case you have checked Federal and
the load the US military is using is
41.745gr IMR 4064 and my load is 42.2gr IMR 4064 )

So FED 41.0gr, US 41.745gr , mine 42.2gr all IMR 4064
That is the powder to use

All use a standard primer so your BR2 is correct

Start with 40.7gr and work up in .3gr intervals until you get
to about 42.5 or 42.8gr with 5 rounds of each weight

Knowing the other accuracy loads you can test a smaller span
of powder weights
By only going 0.3gr you will be closer to your load

For example if 41.6gr, 41.9, 42.2 and 42.5gr is a node
go for the middle and see how that works in 0.1 gr
intervals

( you may have trouble with FED. brass, it is softer
I only get about 3 loads before the pocket will not hold
the primer, other brands go 5 to 7 loadings )
 
.Firewrench:
Start with 40.7gr and work up in .3gr intervals until you get
to about 42.5 or 42.8gr with 5 rounds of each weight
Click to expand...

That sounds like a solid plan. I already know that Federal GMM 175's shoot 1/2-3/4 groups at 200 yards in my gun which is outstanding. I would like a bit better velocity if possible, the factory GMM velocity in my AR10 is 2400 fps, 16.126" barrel....I would like to get closer to 2500 fps, but I won't sacrifice accuracy...So if it groups best at 2400 then I'll just live with it.

Either way I'm excited to get started.
 
Hard to argue with that kind of accuracy but it is pretty slow.
I am loading Varget a grain below Hodgdon maximum for the 175 SMK in my .308 bolt gun for 2650 fps.
 
I use both those components in 308 but in a 24" bolt gun . Your Fed brass should be gtg so I'd start 39.6gr , err wait what ??? Yeah I said "I'd" start there , only because I generally can't get past 42gr in my gun using LC cases . Sticky bolts anything more then that . But I'm lucky I've tested those components several times so I know where to start and where "I'll" likey end up .

Why 39.6 ? because I recommend 308 in .4gr increments . Why ? couple reasons . One is I believe 1% of max charge is a good increment to load in regardless of caliber . 2nd is if you feel once you get close to your ultimate charge and for what ever reason you feel tweaking the charge is best to fine tune the load . You just split the difference and load .2gr lower and .2gr higher to see if they do any better . Meaning you run your development in .4gr increments and find 41.6gr grouped best . You then can go back with 41.4 , 41.6 , & 41.8 in 10rd lots to confirm this is the zone you are looking for . In 308 IMHO .2gr or less will not be noticed so loading in .1gr increments is really not going to show much difference . At least not with the firearms I shoot .

The other thing you may consider because you are in fact looking for higher velocities . You can run a ladder test working up in .5gr increments from 39gr to 46gr loading one round at each increment . This will allow you to find the max charge/pressure your rifle can handle . You then back off 5% or so and work back up in .2 or .3gr increments looking for your best group in 5 or 10rd groups .

You could also do a more traditional load development starting low like 39 or 40gr but this time only load one or two rounds per increment for the first two or three loads . Reason for this is you already know it will be very unlikely you use the lower charges so you use those as safety rounds making sure you're not starting out over pressure . Then as you get closer to the charges you will likely need to use to get the velocity you want . You load at least 5 shots at those charges .

Here is a pic of a load development I did using that method . As you can see I only used a couple rounds at the low charges and increased the number of rounds at each charge as they went up . Also notice I went up in one grain increments at first then dropped down to .5gr increments . In this specific case I had never used any of those components together before . It was the first time ever using RL-15 and the 168gr BTHP ( Hornady ) so not knowing how any of it was going to react in my rifle I started at the low/start load and worked up . Now I knew it was very unlikely those low end charges would cause an issue and could probably have started higher . I went low to be safe and just moved up fast at first .
hX3EoL.jpg
 
Last edited:
Really good intel here. I write the pwdr gr on the brass with a sharpie.

I also try different powders. Benchmark will let me load in a wide gr variation and still be very tight at 200. I really wanted it to be Varget that did that.
 
Sierra manual suggests a 38 great starting load and 42 Grain max hodgdon suggests starting at 41.5 and the max is 45.6(compressed
Click to expand...
Do they list what the round was shot from. Gun or test barrel?
I reload a lot of 06 but for military guns not for bench or hunting.
I have never started at lowest recommended load since in the past I have found them to be very inaccurate in the guns I have loaded for. From a great hand loader that showed me the ropes, I always start 20 to 25% above the minimum suggested and work up in half grain increments.
So between the two listed min max of 38 to 45.6 that leaves a range of 7.6 G.
The 25% would be 1.9, so my starting level would be 38+1.9 or 39.9 or round it to 40.
To me your 40 sounds like a good starting point.
 
Mississippi --

I did not know you will be using a short barreled rifle
In my research on this load I noticed that those with a
20 inch or shorter barrel did better with Varget powder
I did not continue with that research because I needed
info on a 24 inch barrel

Do your research !!
 
40 is below the current Hodgdon minimum. However, as every manual will be slightly different due to the tests being done with different components, powder lots and climatic conditions on the day of the test, that's not really a big deal. Partial to Lyman's data myself. Hodgdon's site has some oddity issues. Like using magnum primers in magnum named cartridges and match primers with match bullets. Isn't necessary. Anyway, the data in manuals are averages in the first place.
41.5 to 45.6 isn't a lot of difference either. It's just 4.1 grains. Eight loads at half grain increment increases from 41.5 to 45.5(probably jump the .1 to .6 myself.). Compressed loads are nothing to worry about.
What Federal used is irrelevant as you cannot get the same powder. There is absolutely no way you can tell anything about a powder other than its colour and the shape of the granules by just looking at it either.
The ladder test doesn't tell you much about the accuracy of a particular load. Only tells you where it hits in relation to other loads. Not much point doing that with a match bullet.
 
. In my research on this load I noticed that those with a
20 inch or shorter barrel did better with Varget powder
I did not continue with that research because I needed
info on a 24 inch barrel
Click to expand...

That's interesting.... Because better velocity in every manual is achieved with IMR 4064 than Varget using 175 gr SMK'S......And exhaustive reaearch has shown the highest velocity powder in a 24" barrel will be highest in a 20", or 16" barrel as well. I have found in my experience that to be true.

But I do have some Varget and I may try it..
 
The ladder test doesn't tell you much about the accuracy of a particular load. Only tells you where it hits in relation to other loads. Not much point doing that with a match bullet
Click to expand...

I disagree fully with that . A ladder test if done right will tell you your max pressure the firearm will allow . In Mississippi's case with this specific load . He is looking for the most velocity possible from this load . Meaning he's not likely going to be satisfied with a mid charge/pressure load that gives just OK velocity . So in this specific case ( not all ) a ladder test to find his max pressure first then backing off 1.5-ish grains then working back up in .2gr or .3gr increments will let him know if this powder ,bullet combo will ever give him the accuracy he wants at the velocity he needs .

You can achieve the same results in multiple ways . OCW does a very similar thing in finding best load . Even a traditional load development will find you your max pressure most of the time . How ever those other methods cause you to shoot more down your bore while expending more components then needed . Remember the OP has some parameters already set that need to be achieved . So blowing by those lower charges while still being safe can actually work better in this specific case . YMMV :)

I'll add that I don't disagree that a different powder may be needed to get the higher velocity . I to agree Varget may not be it though . CFE-223 might be worth a try as well as AR-comp but based on some other posts the OP had made in other threads . I know he is trying to duplicate the results of the Fed GMM loads he tested so sticking with IMR-4064 for now seems perfectly reasonable .

As far as 39gr being below hodgdons start load

my Sierra manual suggests a 38 great starting load and 42 Grain max. Meanwhile hodgdon suggests starting at 41.5 and the max is 45.6(compressed)....That is a big difference!
Click to expand...

I personally never completely ignore the manufactures suggestions of one of the components I'm using if this is the first time ever using this specific combo of components . If Sierra says 38r is start load for there 175gr smk . Who am I to say "no" I'll just start very close to there max .
 
Last edited:
Metal God pretty much summed it up. I'm trying to get Federal GMM accuracy at 1/3 the cost. If I can do a bit better than 2400 fps with the same accuracy, or better, that would be ideal......But it is hard to imagine doing better than 1/2-3/4" groups at 200 yards. In fact that is probably about as well as I'm capable of shooting using my current setup.

Like I said, ideally I can get the same accuracy with an additional 50.... Maybe 100 fps. But really the velocity isn't a deal breaker. I'm going to use the load to shoot in the new provisional AR-10 F-CLASS 600 yrd slow fire. So since I will be firing a known distance, and there won't be a stability issue at that range with a muzzle velocity of 2400 fps, then it isn't that big a deal.

But as Metal God said, I'm trying to duplicate Federal GMM results so the component choice isn't random. I know I'm already deviating a little using BR-2 primers instead of 210M, but I don't think that will make much difference.
 
Also,
I have decided to take a posters advice and I loaded 2 rounds at 41 gr, 41.5, 42, 42.5 & 43......Just to see if I find any pressure signs.

I checked my Lyman 49th manual and Lyman has the max load at 44 grains...Just for reference the max in Sierra's manual is 42.8 and hodgdon website says 45.6. given what I have seen in the past, I would bet $100 that 45.6 is wayyyy to hot for my gun. But if 43 gr shows no pressure signs I'll try going up to 44.

That way I know the range I can safely work in and not need to pull a bunch of bullets.....Been there, done that.
 
Update

I tested two rounds each at 41gr, 41.5, 42, 42.5, & 43.

Each case was full length sized using RCBS die and trimmed to min. Bullet seated to Manual (and factory Federal GMM) COAL and Base-Ogive.

Nothing remarkable until 43 gr, at 43 Grains primers were noticably cratered and flattened. While reading primers is hit-and-miss, they were not flat or cratered at all until I hit 43 gr. Extraction was still normal and the case head expansion was normal but the relative condition of the primers suggests, in my experience using BR-2 primers and this rifle, that 43.5 is probably the upper limit with 44 likely resulting in loose primer pockets and irrigation extraction.

All this really means is that Lyman appears to be the most accurate on the min and max range for IMR 4064 with its minimum charge being 39.5 and max being 44 graines.. Hodgdon is too hot at the maximum and Sierra too low at their minimum.
 
You must log in or register to reply here.
Back
Top