Bad idea?? Replacing FN bullets with 168gr

[BeltfedMG]

Buddy of mine was takin 308 FN millitary surplus and takin the 150gr bullets out, remeasuring the 44gr of powder to 40gr, puttin the 40gr back in the factory FN cases and puttin a 168gr bullet in it then seating the rnd. The other week he was doing it without taking any of the powder out, was using the 44gr the factory rnd comes as. I found out he could blow up his gun that way now hes takin 4gr out of the factory load when replacing the 150 gr bullet with 168. I dont imagine this will blow up his gun as the others may from what i heard but hes not really gonna get match results from this is he? Hes a cheap bastard, i am too but i atleast buy PPU 168 gr if i want somewhat match ammo. Any advice as to wether or not hes gonna hurt his gun or himself doin this?

 

[longdayjake]

44 grains? If you find out what kind of powder he is taking out then it might be more helpful. I have been loading up .308 for a while now and depending on how fast the powder burns you can put anywhere from 38 grains to 47 grains with no problems. I personally think he will be okay but who knows without knowing the powder that is in there. Usually factory loads are on the light side. Take that for what its worth.


Just realized you were talking about military surplus. Hmm... could be on the hot side.

 

[BeltfedMG]

Hes using whatever the factory powder is in the FN ammo, all hes doin is takin 4gr's out and puttin in a 168gr bullet.

 

[ants]

There are generally signs if the rifle is overpressured. The lugs lock the bolt shut, the brass flows into the extractor recess, the base of the brass case increases diameter and drops the spent primer out of the pocket. If these signs are present, get away from him. Once I got hit with debris in the ear and lip when some guy's rifle blew up next to me. It isn't fun.

Your friend is not wise, when he can simply buy 148 or 150 grain match bullets. Sierra Match King #2190 are 150 grain hollow point boat tail bullets, and they are cheaper than the 168 grain counterpart. They replace his 150fmj perfectly, and he will get much better accuracy.

 

[Ben Shepherd]

Do you have access to a chrono? Could be VERY helpful in this situation.

Check the velocity of the factory slugs against speeds listed with the same weight projectile in several manuals. See how they compare.

Then back the charge down a bit with the 168's, and check them against published data for a 168 slug. Then as long as your velocity and powder charge increases are linear, you shoud be able to go to the mid point of the listed velocities for that weight slug.(ASSUMING there are no pressure signs before that point.)

 

[qajaq59]

I'm not sure if the gun will blow up. But it still isn't something I would do. Gun powder's a whole lot cheaper then surgery.

 

[Walkalong]

Sounds fine. Like posters have said, check for pressure signs, and check velocity with a chrono if you have access to one.

 

[Remo-99]

Let me get get this straight, he was removing a 150gr bullet and 4gr of powder, to place a 168gr bullet. Ok that sounds fair, But then you say he is not removing any powder now to replace a 150gr bullet with a 168gr bullet to use with the same powder charge of unknown source/make. I hope for his family's sake atleast, he's life insurance is in order.

 

[Ben Shepherd]

I actually reccomend you DON'T pursue this WITHOUT a chrono.

Your friend is guessing. With a chrono, it's an educated guess.

 

[NCsmitty]

The 10% powder reduction that you are using should be ok. Luckily NATO 7.62x51 surplus is usually loaded to a bit lower pressure than a regular 308 Win. and that's why your friend has gotten away with it so far. He is FN stupid.

NCsmitty

 

[30Cal]

I'd go with the 150 or 155gr SMK's.

 

[fitz47]

Bad,bad,bad Move To Many Unknowns.

 

[goon]

Yep, what your buddy is doing is a bad idea.

In his position I'd pull the bullets and dump the powder, then start over with new powder that I had REAL data for and work up a load in the primed cases.
You really couldn't even just switch a 150 grain SP bullet without knowing what the powder charge should be adjusted to.
Bullets of the same weight still have different shapes that can change the space inside the cartridge. That can increase pressure and too much of that can scatter parts of you all over the place. True, it probably is not real likely, but it is more likely than it would be if you just worked up a load with known components.

And last, ask your buddy how much his eye sight is worth to him.
A pound of Winchester 748 will run him about $22. It will be enough to get him about 120-140 rounds with a "normal" .308 load.
I'll bet your buddy's eyes and fingers are worth more to him than $22.

 

[jjohnson]

Never Survive a Day in Combat

I don't think your buddy would have made it a day in my Combat Engineer unit. Somebody would have helped him have an accident just to get it over with and keep everybody else safe.

We played with explosives for a living but kept alive and all our fingers and eyesight be respecting the stuff.

He might stay lucky, but I agree - too many variables. Make sure you stand behind him when he test fires his loads. Be ready to apply first aid.

 

[BeltfedMG]

He got them to work and shoot 1/2" groups with them. I stood about 20 ft behind him , DIRECTLY behind so any shrapnel would hit him not me and i was on a knee down low. No signs of over pressure (as to what he told me to look for as he pointed them out) and he shot absolutly great groups with it. I wont have him make me any but it worked for him. I have had guns blow up on me and shrapnel stuck in my leg bones, some still there. Not doin that again (didnt happened from doin what he is doin, no reloads involved)

 

[Remo-99]

No signs of over pressure

Your buddy may have worked those loads back up to the original powder charge.
Bottom line is he's gonna be running higher pressures, by replacing a 150gr with 168gr.
Often surplus brass is a little harder and more brittle, this may not indicate the very same signs of pressure as would the softer commercial consumer brass.
Primers also maybe much harder than commercial types.

Your buddy's load data would like this;

Case - FN 7.62x51 nato
Bullet - 168gr
Powder - Unknown 44gr
Primer - Unknown
Safety- UNKNOWN.

If a case did happen to blow out, the action will probably hold together, if it's a modern boltaction, and the minimum danger is getting sprayed with brass shapnel and high pressure hot gas.

I remember hearing about a guy a few years ago in my local area, who had to be rushed into surgery to remove a rife bolt that was imbedded in his cheek, after he was messing about with surplus ammo and test firing it.

 

[goon]

Also, it may not be safe to just reduce a powder charge.
Burn rates are strange things that are beyond my current comprehension.
But I do know that they often have a "range" where they are predictable. Anything above or below that range could be potentially unsafe.

I still heavily advocate tossing the pull-down powder and reusing just the primed brass.
I've even tossed my own pull-down powder before from handloads that I made.
It just isn't worth it to blow your face off trying to save $10.

BTW - +1 on the Engineers.