Need some advise from hand loaders for a 308 please

[bfoosh006]

I suggest you try some reloads with IMR 3031.

[Unclenick]

Bfoosh006,

That's a good idea. The max loads will be a bit slower, but the faster powder will make for a shorter barrel time, and that may be what's needed to synchronize to harmonic muzzle swing in the short barrel. It would be interesting to see.

Originally Posted by jimro

On the flip side of that, Slamfire has reports of slamfires with milspec large rifle primers as well. It could just be a matter of time, but as of right now I'd say that the 210M primer has demonstrated itself reliable enough for semi-auto use by the military.

I was present at one slamfire of a Garand using LC 72 M2 Ball. So neither the primer hardness, nor proper primer seating are absolute guarantees against slamfires. It's just a question of reducing the probability some. Slamfire also posted the report on M16 slamfires for which Lake City reduced the primer sensitivity and apparently that reduced the slamfire incidents successfully.

I have to suspect, when you get a slamfire with military ammo, that there's a marginal mechanical spec somewhere in the mix.

I recall back in the early 90's that Federal denied their primers were more prone to slamfires than others. They felt that reputation had arisen simply because their primers were used by more match shooters than any other brand at the time.

I'm not fully convinced, though. It's just a gut feel, probably biased by personal experience with Federal's pistol primers that handguns with weak mainsprings will often fire them when others fail. I don't know that this characteristic carries over to rifle because I haven't ever lightened mainsprings in mine. But from all the slamfires reported with Federal primers in the past (the ones they dismissed), including the two OOB firings Slamfire had with them, that they are at least as sensitive as anyone else's. Without performing an H-test, though, there's no quantifiable comparison that can be made.


Grubbylabs,

One other thought is to ask if you looked the crown over carefully. One article I read long ago was about the purchase of one of Dave Manson's crowning tools, and the two co-purchasers got some of their money back by crowning rifles for about 15 members of their club, and, IIRC, charging them only if accuracy improved, which it did in 50% of them. So it's a common shortcoming.

If you know someone with a lathe and dial indicator, have them chuck the bolt up and check for bolt face squareness and squareness on the back side of the locking lugs. Because truing a bolt face or lapping lugs increases headspace by the amount you take off, an extremely crooked face may mean getting a new bolt rather than messing with the current one. Also watch that the firing pin extension remains within spec if you alter that.

[Bart B.]

Here's my take on squaring up bolt faces........

As the boltway may not be aligned with the chamber axis, turning a bolt in a lathe on its center then facing it may end up with the bolt face still out of square with the chamber axis. I've seen that happen, expecially with forged receivers. Cases fit in the chamber and that axis is what the bolt face should be square with.

Face the receiver first so its square with the barrel tenon threads. Then lap the lugs to full contact. It's now ready for a closed bolt (and held in that position 'cause that's where it is when the round fires) in the receiver to be faced with one of these or the likes thereof:

http://www.midwayusa.com/product/493...-remington-700

Either face lapping with compound or cutting with an end mill works fine. Headspace will increase a little bit. If too much, the barrel needs be set back one thread then rechambered.

Plus, squaring up the receiver face typically ends shot walking from barrels getting hot.

[Jimro]

Unclenick,

I've had that feeling as well, knowing enough competitors who switched from FGMM primers to CCI or Wolf after having one slamfire. However since I can't quantify that feeling in any meaningful way I try to look at the facts as they are, and that is that slamfires are a very rare event.

Of course the lack of evidence of slamfires with Mk316 ammunition shouldn't be construed as evidence that FGMM primers aren't more sensitive than other primers, just that they are robust enough to serve in a milspec load with semi-auto rifles with free floating firing pins. It should also be noted that handloaders are using many more loading tools and techniques than the Federal ammunition plant that is putting out Mk316 which gives a good explanation why one process producing one load shouldn't be considered as proof positive that every process and every load using the same component will end up with the same net reliability.

Jimro

[Bart B.]

Of the 20 or so slamfired cases I've seen from Garands, every one had a full, normal dimpled primer flat with the case head. Same shape and depth as normally fired ones. Which pretty much convinced me the hammer made a normal, full-force fall on the firing pin in a well closed bolt.

[Rimfire5]

You didn't say what twist your rifle was or if you were shooting with iron sights or a scope. If iron sights, I would suspect that sighting was the critical component in accuracy more than the rifle itself.
If you were using a scope off a rest, then you have a starting point to explore if you can improve the effective accuracy by finding a load that your rifle likes best.

Even if you don't have a super accurate rifle, you might be able to find some loads that could flirt with the 1 MOA result if you play with velocity and maybe seating depth (AOL).

If you aren't turned off by the price of Federal Premium Gold Match 168s or 175 SMK factory ammo, they are both good indicators of .308 factory ammo that will give you indications of what high quality factory ammo will do. If your rifle has a preference for bullet weight, they might also tell you if you should concentrate on heavier or lighter bullets.

Since you already have at least one powder/bullet combination that is performing close to 1 MOA, you also have a hand load starting point.
Start with a couple of powder and bullet combinations that have shown the best results. Just keep detailed records and adjust the powder changes in regular increments, probably in 50 fps increments until you get a feel for where to really concentrate.

Then work up some loads in sequence around the loads that gave the best results. You might get lucky. At worst, you'll find out what your rifle prefers and determine what combinations give the best results for your particular rifle.

While is isn't the same caliber as you .308, by doing some analysis, I helped a range buddy with a 1976 Colt HBAR in .223 that he couldn't get to shoot accurately. And he couldn't get it to average under 1 MOA even shooting from a rest with a Leupold scope with max power of 18x.
From his data, it was obvious that his 1:7 twist was better with 77 grain SMK but really got results when the velocities were in a narrow range. Turned out that if he kept the velocities between 2550 fps and 2600 fps with SMKs he averaged 0.873 with H4895.
With Varget the range was very narrow between 2450 and 2500 fps and he averaged 0.812. Above 2500 he averaged 1.106. Below 2450 he averaged 1.209.
With Berger 77 OTM bullets and Varget powder, he averaged 0.809 between 2267 and 2322. Over 2322, he averaged 1.364.

I have found similar, but not as severe velocity preferences as I found with that Colt when loading for my .308 bolt actions and my M1A. Mostly, I find my rifles have stronger bullet weight or bullet length (touching the rifling) than velocity preferences, but they are sensitive to velocity when trying to find really accurate nodes.
My M1A has a 150 gr bullet range from 2600 to 2642 fps, a 168 gr best performance range from 2488 to 2525 fps and a 175 gr best performance range from 2459 to 2482 fps. With the right hand loads it shoots less than 1 MOA by a pretty good margin.

You may find that kind of velocity preference with your rifle. If not, you'll have the data to know what your best loads really are.

[Eppie]

Unclenick said: 10,275 Try a box of Federal Gold Medal Match ammo that uses the 168. It tends to shoot well in most any gun chambered for the .308. It would give your expectations a baseline to work from.

Do the above.

Then you will have isolated what the gun is capable versus the handloads. I always keep some FGMM 168 on hand so that when I have problem I can isolate it the component. I call them my control group.

Having said that. I can also say that I used to own a DPMS .308 and it was never that accurate. I eventually migrated to a POF 308, that was an improvement but still not as good as a $600 Remington 700.

[grubbylabs]

Thanks for all the help so far, I will be looking into a few of the suggestions, like getting some federal match ammo. I checked the OAL on my rounds, and the 2.800 is just barely short enough to fit the magazine. I was seating just a little shorter to keep from having seating problem. I think I am going to try the IMR 4895 still. I am also going to try some Speer bullets and and go up to a 180 grain bullet, and possibly a 190 grain bullet.

[Bart B.]

I don't think any bullet over 170 grains will shoot more accurate.

[grubbylabs]

Just going to try it so I can say I tried every thing. At this point I am not even sure trying a different powder will make a difference, but what the heck. I might even try upgrading to a higher quality scope in the near future to see if that changes any thing. Its wearing a less than $200.00 Vortex.

[TATER]

Nothing wrong with a vortex, A good trigger could make all the difference too though.

[Bart B.]

If you can, slug the barrel with soft lead then measure it's widest points with a good micrometer. If nothing loaded seems to shoot worth a darn, the barrel's groove diameter may be large enough to drive a pickup truck through. Hopefully, it won't be more than .309" which is about the limit for MOA accuracy needs with .308" bullet diameters in well loaded ammo.

I've seen a few .30-06's with .311" groove diameter barrels that no .308" diameter bullet would shoot inside 3 inches at 100 yards from any set of components under it I tried. There's no reason a .308Win./7.62NATO barrel would be different.

[grubbylabs]

I had not thought about slugging the barrel, I might have to try that. Going to wind up with a 30 cal mold at some point any way. I wonder how load development for the 30 cal will go compared to how it went with my 223?

[chris667]

3031 will give you higher velocity with lighter bullets out of a 16" barrel.
I use 43.7 g of IMR3031 in a Winchester case with a 150g bullet.
I use 45.0g of IMR4895 in a Winchester case with a 168g bullet.

[44 AMP]

Going to wind up with a 30 cal mold at some point any way.

If you are talking about cast bullets in a gas operated gun, (AR?) be prepared for issues. Lead, bullet lube and powder residue all together don't do well in some gas systems.

if you are talking about using a .30 mold to cast a slug for slugging the barrel, use pure lead, and pay attention to the "feel" when driving it through the bore. A tight spot in the bore will show by feel, and by the diameter of the slug after it passes through it. A loose spot will only show by the "feel" of the slug going through.

Good Luck!

[grubbylabs]

It took a little work in the AR15's but I finally got a load that works well with cast in it, so I think I should be able to find something that will work ok in my DPMS 308.

I never did see any leading or lube issues, just shotgun pattern sized groups until I got the bullet going slow enough.

[Reloader2]

Originally Posted by bfoosh006

I suggest you try some reloads with IMR 3031.

I've been loading 165's with IMR3031 for my grandson.

[bfoosh006]

The guys with 16" SOCOM's were having the same problems... IMR 3031 solved most of the accuracy issues.

A Gentleman by the call name of RAMMAC on www.m14forums.com.... has a TON of info on IMR 3031 in a 16" barrel SOCOM.

Here is the link to his section on m14forums.com....

http://m14forum.com/rammac/

I truly suggest you try some IMR 3031.

[rboyer224]

Hello all. Just joined this forum to try to figure out my problem. I also have the DPMS GII Recon. The pictures are of the factory ammo I've shot through the gun so far. I can completely understand having pressure issues with handloads, but factory ammo?? Now, I do have a silencer on it also, and understand that increases overall pressure and most likely effects timing, but I didn't expect it so much with factory ammo. Since firing these, I've added an adjustable gas block but have not had a chance to shoot it again. Still can't believe that the silencer creates enough pressure to blow out the primer!! I guess I could also try it without the silencer and see the difference.

[Tinbucket]

IMR 4064 is what I use most loadings.
A Speer, and bullet does matter, 150 grain-47.0 grains0f 4064. CCI primer.
give me 2800 fps out of Remington 600, with it's short barrel.
A little more than NATO pressures if you're shooting in an auto.
Any of the 150 grains will probably not be any pressure issue with the load.
I've got a few 168 grain load but anything heavier I load in the .30-06.
The Old Lyman and some other manuals have higher pressure higher velocity loadings and I have some still packed up.
This load came out of Speer manual, I think

[Jimro]

rboyer224,

I don't know what Hornady loading you are using. Based on the cartridges I'm guessing you are using a "Superformance" load.

It is recommended that to get the best functioning with Superformance ammunition in gas operated/gas piston semi-automatic or select fire guns, rifle length gas systems with 20 inch or longer barrel lengths are best for reliable firing and extraction. Any other configuration, particularly shorter barrels/gas systems are best served with the installation of an adjustable gas system, ESPECIALLY if a suppressor is to be installed.

Due to the longer duration of peak pressure produced by Superformance™, the post peak/declining port pressure at common carbine and mid-length gas port locations is still higher than that produced by standard propellant. This has a tendency to flood the system with a larger volume of gas, at a higher velocity, that tries to open the bolt of the gun too fast. It’s a timing issue. The cartridge case is still swollen from the application of pressure during firing while the gun is simultaneously trying to extract the cartridge case before it has had an opportunity to settle back to its original size, or more simply: the gun is still in the process or firing while it’s trying to extract the cartridge case.

If the firearm and the ammunition are not in sync, there can be what is commonly identified as “pressure signs” on the cartridge case. This is exhibited by the movement/marring of the head of the cartridge case, cratered primers, flat primers, ripped or ruptured cartridge cases, “popped primers”, and/or any combination of these effects. If any of these “pressure signs” are apparent, stop firing immediately. If an adjustable gas system is installed, it is advisable to reduce the amount of gas flowing through the system by closing the gas port until the gun operates correctly.

With the installation of an adjustable gas system, gas pressure can be metered to a point that enough gas is applied to open the bolt, but at a slower rate to allow the cartridge case to return to its original diameter prior to the movement of the bolt, and thus allow for proper extraction.

http://www.hornady.com/ammunition/su...rated-firearms

Just know when you use that adjustable gas block to tune your rifle for the Hornady load, you will get poor extraction from regular ammo.

Hope this helps.

Jimro

[Mike / Tx]

grubby, I know this is sort of an apples to oranges approach but I'll throw in anyway.

I shoot a short barreled Ruger a LOT. It sports a 16.5" pencil thin barrel as well, and the whole thing with 5 rounds ready to hit the woods only weighs 6.5 pounds, so it rocks around a little when fired form the bench.

I tried ALL of the highest recommended powders and worked through the loads listed here and elsewhere, shot some of the top notch match loads, and all trying to find ANYTHING that shot as good or better than the plain ol Rem CL's I had been using.

Just about the time I decided that 1.5" was as good as it gets no matter what, I went to loading up some reduced loads using H4895 for my grandson and wife to use on some feral hogs. I had, in the past, loaded them to the very bottom of the data using some 125gr bullets when the kid was only 3 so he could learn to shoot without getting pounded to death. Well these were maybe a grain below the standard start load for the 150gr bullets. The funny thing was they shot EXCELLENT. So I worked them on up to see how far this would go. I ended up matching the velocity of the Rem factory loads only instead of the 1.5" groups I was getting right at or just below 1" at 100yds using the Rem 150gr bulk bullets.

I pretty much cut the group size in half, using H-4895. I realize that your rifle is gas operated, but even still working up form the starting loads should give you enough umph for ejection, and you could be like me and hit something that you actually like.

Just throwing that out there as I have been there with the short barrels ..

[rboyer224]

Jimro,

Thanks for that info. I do understand why it happens (now), but did not know about that ammo. It was the Superperformance ammo. I do have an adjustable gas block on it now and will try again. I completely understand the whole chain of events causing the swiped head and all that, however,..... The bulges caused by the ejection holes still have me a little confused. I understand the timing and that the bolt is trying to pull the case out before it has shrunken back down to size, but those two ejector port hole bulges must be caused at the very moment the round is fired. That's the only point where the pressure is that high and the bolt is not turning yet, which pushed the soft hot brass in to those two holes. I don't see how closing off the gas port can have any effect at all on the initial pressure and those two dimples/bumps???? With the adjustable gas block and the timing being corrected, I can see how it will no longer swipe those two bumps off, but they would most likely still be there correct? The gas block is not changing the pressure that the round creates, it's just changing how much of it comes back (and when) to the bolt. Does that all make sense? Anyway, thanks for that link. Luckily I only had a few shots before I realized that this was happening. Hopefully the gas block corrects it all. Thanks again.

[Jeff2131]

IMR3031...4064 is too slow for .308 in ar's.

[Bart B.]

IMR4064 in .308 Win cases has been used in AR10, M1, M1A and M14NM rifles with 168's for match winning and record setting accuracy. The best of them shot 4 inches or better at 600 yards.

In the '60's and '70's, military teams tried IMR3031 in .308 Win. ammo for M1 and M14 rifles and it did very good, for a couple dozen shots, then powder fouling degraded accuracy. IMR4064 loads would go 60 t0 80 shots before cleaning was needed to maintain best accuracy.