M14 Forum banner
1 - 20 of 24 Posts

·
Registered
Joined
·
778 Posts
Discussion Starter · #1 ·
If this has been mentioned in this forum already I missed it. Tried a search. the loading information for .308 service rifle in the Hornady 8th edition seems to be on the low side for IMR 4895. Maxing out at 41.4 grains with the 168 grain bullets. I've seen other loading info up to 43 grains. I'm going to start at 40.5 grains with a 168 gr SMK. Is anybody else out here loading much beyond this?
 

·
Registered
Joined
·
311 Posts
Hi Mustang,

I too have wondered the same question, I have the Hornady manual and the new Sierra. The Sierra shows a max load of 41.3g of IMR 4895 @2600 with a 168 SMK at 2.80 OAL.

I load the 168 SMK to 2.80 OAL, with CCI#34 primers and 40.6grs of IMR 4895 in Lake City brass with roughly .002 neck tension, across my chrono that yields a nice 2525 fps avg velocity for 20 rounds. I stick with 2500 fps is plenty fast for me, I never shoot beyond 300yds..just dont need the extra 100 fps or so. Also by staying with 40.6 grains...just in case my Dillon powder measure is sloppy and I get a .1 or .2 more powder, I not on the bleeding edge of safety, I have almost a full 1.0 grain powder of safety margin.

I also wonder about the people I heard so many people say 41.5 is "standard" loading for me 41.5 is not necessary. Again my target velocity is 2500 fps. Some people may need the extra 100 fps... your results may vary.

Start at 40 grains and work up slowly to find your sweet spot. I'm sure you realize that military brass has less case volume and this definitely effects my loads. Commerical cases can have slightly more volume.
 

·
Registered
Joined
·
778 Posts
Discussion Starter · #3 ·
Thank-you for the info. I'm still pretty new at this. I've been shooting DAG in my backyard at 200 yards and have been more than happy with it. Recently made friends with a farmer with a huge pasture and will be able to stretch out to 800 yards and more. Thats as far as my rangefinder will go. Want to see what my rifle and I am capable of doing without pushing the pressure limits.
 

·
Registered
Joined
·
9,835 Posts
...I've seen other loading info up to 43 grains...
Read their information carefully, what rifle or barrel did they develop their data with? Most other manuals are using 24" bolt rifles for their .308 load data and those type of actions can and do usually use more powder since they handle the chamber pressures better.

All that being said, the volume of the brass is what makes the difference. When I use a 168gr Amax bullet and my Lapua brass then I usually end up using about 42 grains of IMR 4895. On the other hand, if I use a case with less volume (like just about any other brand since my Lapua brass has the most volume of the brands of brass I use) then I drop down to about 41 grains of IMR 4895. These charge weights give me muzzle velocities in the 2550 - 2600 fps range which is my personal goal. Now for pure accuracy lighter loads seem to work best for me. 40 - 41 grains of IMR 4895 in a standard commercial case and the 168gr Amax will make some pretty nice groups at 100 yards.
 

·
Registered
Joined
·
510 Posts
The Hornady people used a 22 inch M1A with a 1 in 10 twist.
See: page 497. 308 Winchester Service Rifle.
The lowest bullet weight listed is 155gr but that's another thread.
 

·
Registered
Joined
·
778 Posts
Discussion Starter · #6 ·
I'm using brand new Winchester brass with Winchester primers. I aso have a Springfield M1A Loaded. I don't believe I'll ever catch up to the capablities of this rifle but I will have fun trying.
 

·
Registered
Joined
·
9,835 Posts
When the bug gets you then you will drive yourself nuts with all the intricacies of reloading and rifle operation but until then just experiment with a load using 40 - 41 grains of IMR 4895, a good 168gr target style bullet (my favorite is the Hornady A-Max but an awful lot of people like the Sierra Match Kings), and the cases and primers you have and I think you will be impressed with the results.
 

·
Registered
Joined
·
1,030 Posts
You are working with heavy for cartridge bullets at the 168 gr. level and you have to take extra care to ensure all of the conditions and variables regarding reloading 308 Win ammo are taken into account. I would recommend keeping to the conservative level and working up slowly until you have identified the load that works best with your components and rifle. Hornady manual has to keep loads within established safety ranges for a range of rifle types. My M1A requires a different approach to reload compared to my PSS.
 

·
Registered
Joined
·
9,835 Posts
While 38.7 grains seems to work for some rifles remember that there is a minimum port pressure required to make the gas piston move with enough force to reliably operate the rifle. I like the lighter loads for the fact that they don't beat the rifle up and the throats will last longer and they usually group tighter, at least at 100 yards. But a new reloader needs to be aware that too light of a load can cause issues too, in fact a lot of reloading manuals warn against loading anything below their minimum loads, which is significantly below the 38.7gr load mentioned.
 

·
Registered
Joined
·
8,673 Posts
In my experience, 41.0-41.5 gr IMR4895 in NATO brass is the sweet spot for a 168 SMK. Chronograph verifies this out of two NM and a SM rifle. Spot on around 2600 FPS. This projectile performs well in that particular velocity envelope out of the M1A.

I would start at 39.5 minimum and work up to 41.5 gr. Look for flattened primer condition and recoil report. A chrono sure helps. Depends on brass volume and that's where these $100 chronographs really help save in the long run.
 

·
Registered
Joined
·
2,604 Posts
I've noticed that the main load I use, .308 SSTs over 42.5 gr of IMR 4895, I'm already getting high pressure. So high the headstamp was imprinted on my M1A. I also noticed that Hornady ammo is loaded hot. I like their products, but I really hope they test their loads with each powder and not do mathematical guess work.
 

·
Registered
Joined
·
3,665 Posts
Mustang - I'm using Winchester brass, CCI #34 primers, Hodgdon 4895 and 168gr SMK bullets in 18.5" barrel M-14 type rifles. NOT the same powder as yours, but I've noticed chronograph muzzle velocities well below what the Hornady "Service Rifle" section indicates. Like almost 200 fps of muzzle velocity. Same holds true for VV N-135 as well as the H-4895. The shorter barrel(s) contribute to the lower velocity, but not all of it. IIRC the Hornady test specs also say something about military brass (in addition to the 22" barrel).

This is just an educated guess at this point, but perhaps Winchester .308 cases have more interior volume than some other types of brass do. I've worked slowly up to Hornady's "maximum" loads for both VV N-135 and H-4895. No pressure signs of any kind.
 

·
Super Moderator
Joined
·
11,293 Posts
I find that the Speer manual has hotter info and my results mirror the Speer book. I use 43.5grs to 44.0 grs of IMR-4895 in commercial Winchester cases with WLR primers and 168's. This gets me around 2600 to 2650fps. If I use Sierra's info, my loads are a little slow in the low 2500fps range.
 

·
Registered
Joined
·
778 Posts
Discussion Starter · #15 ·
Thank-you all for your input. I had already loaded 15 rounds at the 40.5 grain level and thought that was being conservative but now I am not so sure. I guess I'll pull these and start over at 39 or 39.5 grains.
 

·
Registered
Joined
·
161 Posts
If you study a bunch of manuals you will find Hornady to be the mildest. Your comments on their loads fits with my observations.

I use Hornady as my cross check. If my peak load is more than hornady max, then I am probably getting up there finally.
 

·
Registered
Joined
·
9,835 Posts
The problem with comparing reloading manuals is that we usually complain about their data without realizing how the little differences between our equipment and theirs has skewed the results of our testing. Even the same bullet weight and profile, made by different manufacturers, will cause small variances that will change our results and make us doubt the accuracy of their published information.

A lot of us don't realize how important case volume is. For example, the 168gr SMK measures (base to tip) 1.202" while a 168gr A-Max measures 1.277". That might not seem like an issue but it is when you evaluate how the length effects the usable case volume (after the bullet has been seated). These bullets have a difference of 0.075" in length. That means that all things being equal (the same case, same TTL, same powder, resized with the same die, the same COAL) the 168gr A-Max will seat 0.075" deeper than the SMK. That's about a 3% change in volume and causes a change of pressure of about 3,300 PSI and a muzzle velocity change of about 35 FPS (the A-Max will have the higher pressure and velocity). So when we try to compare what's in a manual against what we actually measure, we have to use the exact same equipment and conditions as they used to expect to come close to their results.

Barrel length is the other item that has a huge effect on the data. many people will argue about how much difference barrel length makes in muzzle velocity but most people don't compare apples to apples when they come up with their numbers. I've seen people report all sorts of numbers as being the average velocity change per inch of barrel length. If the shooter actually performed his tests then his numbers are only valid for his rifle and ammo. Caliber, original velocity of the bullet tested, barrel condition, and all sorts of other things effect the change in velocity so it would not be surprising to see different results between any two shooter's tests. Most of my testing has held that I can estimate an average of about 150 FPS loss in velocity between my 22" barrels and my SOCOM 16.25" barrel, but that's based on my 168gr A-Max bullets and I haven't really taken notes on the variation using any other bullet as of yet. But I know that people will argue with that data and claim that I'm either too high or not high enough with that number, but they probably aren't using the same powder, powder charge weight, case, case TTL, primer, and on and on. Each of those things make minor differences but they do cause enough difference to cause what seems to be conflicting test results.

One of the things that computer software is good for is modeling real world activities. While they may not be spot on in every case they are very good at recreating the patterns that we see in the real world. QuickLOAD is a very good internal ballistics program that will provide reliable results once you learn how to adjust the inputs properly. In fact, I used some of the data that posters presented here and tested the software to see if my numbers matched their real world experiences. I have kept a file listing case volumes and I used it help with the data inputs and that information along with their posted data allowed me to run the simulations. My muzzle velocities came out a little less than what they measured but when software will come up with a velocity that's only 40 FPS less than the real world I feel it's proven itself to be pretty accurate. Any way, as an experiment I ran a few sets of numbers changing only the volume of the case and the length of the barrel. The results confirmed what a lot of people already knew to be true but it was interesting to see, in real numbers, how little change it takes to create the effects that the software predicted. I used a hypothetical cartridge using a 168gr Hornady A-Max bullet, 42.6gr of IMR 4895, a TTL of 2.81", and a COAL of 2.005". In QuickLOAD this resulted in 2650 FPS using a case with a capacity equal to 54gr of water (this is total capacity without a bullet being seated, the water is even with the case's mouth). The end result is that the data proves that changing the volume of the case has a very large and direct effect on the pressures developed and to a small extent the muzzle velocity. But the barrel length, while having the stronger effect on muzzle velocity, had no effect on pressure.

For those who might be interested in seeing the data that I based this on, here is a link to it.
 

·
Registered
Joined
·
3,665 Posts
RAMMAC - thanks so much for that post and especially the data!

It seems to explain the lower muzzle velocities I'm getting with the SMK 168gr BTHP vs. the Hornady manual service rifle data. It also shows approximately 120 fps drop from the 18" barrel vs. a standard 22". I realize that decrease in muzzle velocity for barrel length only applies directly to 168gr SMK and your load of IMR 4895, but it at least gives me a ball-park idea. Probably pretty close for H-4895.

Does anyone know where to find data on the length of different Hornady bullets? I searched their site and couldn't find it.
 

·
Registered
Joined
·
9,835 Posts
RAMMAC - thanks so much for that post and especially the data!

It seems to explain the lower muzzle velocities I'm getting with the SMK 168gr BTHP vs. the Hornady manual service rifle data. It also shows approximately 120 fps drop from the 18" barrel vs. a standard 22". I realize that decrease in muzzle velocity for barrel length only applies directly to 168gr SMK and your load of IMR 4895, but it at least gives me a ball-park idea. Probably pretty close for H-4895.

Does anyone know where to find data on the length of different Hornady bullets? I searched their site and couldn't find it.
I can extract the bullet dimensions from QuickLOAD and send it to you, PM me with an e-mail address. Do you want it in a spreadsheet or a PDF file?
 

·
Registered
Joined
·
61 Posts
Does anyone know where to find data on the length of different Hornady bullets? I searched their site and couldn't find it.
Applied Ballistics for Long-Range Shooting by Brian Litz, great book lots of info as well as detail drawings and dimensions of the more popular match bullets, want to know the difference in the boattail radius between a nosler c/c and a SMK? its in there as well as a nifty computer program that does more stuff than I have figured out yet
and Brian is a very nice guy GI2
 
1 - 20 of 24 Posts
Top