Help fmjbt diameter all over the place.

[trigger45]

Yeah , I had to run to the other side of the house to see the rest of the photo

Guys I’m really sorry about the pictures. [emoji22][emoji3064]


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[Reloadron]

It's OK and lessons learned.

Ron

 

[trigger45]

To beat the dead horse, FMJ military ball ammo is made with a copper jacket cup that has an open base. The lead is inserted and the jacket is swaged.

Variation in jackets,cores,and manufacturing show up in the bullet base.

As Unclenick's photos show,the variation in bullet bases is considerable.

The base of the bullet plays a major role in bullet accuracy.

Match grade and hunting bullets have the jackets formed with a closed base. Te lead is inserted from the front,then the bullet is swaged.The bullet bases can be far more consistent this way.

It seems you bought a rifle in the interest of accuracy.. I don't know exactly how many rounds of peak accuracy your barrel will deliver, but a ballpark guess of 5000 rounds might not be far off.

You bought 500 rock blasting dust puffing go bang bullets.

Do you want to use up 10 % of your barrel life shooting them?

If you want accuracy for the sake of accuracy, start with a good match grade bullet. You get to have fun picking one.

One of the reasons ball powder is used for military powder is the machinery loading the ammo can be run at a higher speed as the powder flows like water.

The shape of a powder granule is part of what controls burn speed. The little balls would burn as fast as pistol powder if they were not heavily coated with inert retardants. Those tend to leave fouling which can compromise accuracy.

I'm not a match shooter. You have some on this thread helping you. I can say after informally testing several powders for 308 accuracy, Varget was our choice. Others have had great success with 4895, 4064, etc.

I don't know today's recipe, but for a time the Army loaded RE-15 behind a 175 gr match bullet for sniper ammo. I suggest RE-15 might be worthy of a try. Some say it might be Norma N-140 but I don't know that.

If what you are pursuing is tight little groups.....no put down here, but you might make some progress with your bag setup.

Stacking front bags on your rifle case and not having a rear bag at all seems like an opportunity for improvement. so long as you are evaluating the rifle and the load.

I’m saving up for a scope next then bags. I probably got ahead of my self. That is actually my range bag empty and my rifle case is closed cell foam. Had it for a while. This set up has worked for a long time. The table is high. I don’t need it (the bag) too high. Never reloaded for .30 caliber before. Like I’ve said before on other forums it’s the rifle I should have bought 30 years ago. But I got a .270win.

I went back and measured the bullets. They were still larger than they needed to be. In the future I’ll buy a sizer to see if I can use them. They leave too much copper in my barrel to be any good for it. Getting another bullet type from Hornady 168-gr bthp. If it’s like the 87 gr bthp in .243win I’ve used before it’ll be great.

Thanks for your time.


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[Metal god]

I use the Hornady 168gr BTHP as my plinking match loads . Bulk price is good and they shoot pretty well in all my 308’s . If I want to get accuracy and distance i go up in weight to at least 175/8 all the way to 200gr

 

[Aguila Blanca]

Some are range between.308 and .309.

This is my first .30 caliber. But have been reloading for 35 years. Never ran into bullets this out of spec.

The military and SAAMI spec is 0.3090"-0.003" or 0.306-0.309" Yours are way tighter than that.

In other words, your bullets are not out of spec. They are all within spec, and the diameter range of your bullets (.001") is one-third the allowable range per SAAMI specification. It would appear that (a) your expectations for surplus bullets is unrealistic, and (b) you don't know what "in spec" is for the round you are loading.

 

[Aguila Blanca]

Duplicate threads merged.

 

[HiBC]

This isn't science proved by testing. Its seat of the pants opinion.
There are those here who know better than I do.

Eyeballing the proportions of your bullet,the cylindrical body that actually contacts groove dia of your bore looks to be about .375 to .400. + or -.

So something like 125% to 133% of diameter.
I'm not making any hard and fast rule here. Short bullets can shoot good.
I suggest it might take more attention to detail to get them to transition from case neck to throat to leade and on down the bore with the bullet co-axial to the bore.
My theory is ,all other factors being equal,it may be easir to get a longer body bullet headed straight into the bore.
I know,folks DO get lighter,shorter bullets to shoot.I don't know diddly about Palma,but they shoot 155 gr 30 cal boat tails ,a relatively short body bullet, with excellent accuracy.

But I'm guessing the necks are uniform,the ammo is straight and concentric,,and the chambering reamer is optimized to start that bullet straight and square into the rifling.

I would assume its usually easier to get something like a 175 gr MK to shoot.

 

[Unclenick]

I should mention that many bullets also have a tiny diameter increase where a boattail meets the cylindrical bearing surface. This is why measuring across the diameter gives you a better idea of what most of the barrel feels.

As Bart mentioned, bullets that are slightly tight shoot better than those that are slightly loose, especially as throat wear increases over time. Indeed, having a Palma barrel for 308 Win made with a groove diameter of. 3065" is not uncommon.

Your concern about increased metal fouling resulting from tight bullets is misplaced. If it caused a problem, you would expect the buildup to be apparent around edge the throat, but it actually builds up an inch or two down the bore which is where the bullet bearing surface is located when the pressure peak is reached. That high level of accelerating force (typically around 150000-200000 g's in 308 W) actually tries to squash the bullet shorter and fatter which pushes it out hard against the sides of bore. That's what raises the friction to rub copper off in the bore. It is also why undersized bullets will shoot without leaking gas, even though accuracy is compromised by the centering error it allows.

If you have a barrel that fouls too rapidly there are three things that can help. One is firelapping the bore to smooth it. Another is using lubricated bullets; moly coating or hex boron nitride. A new one is Tubb Dust, a powder additive David Tubb sells to prevent copper build-up.

 

[trigger45]

Gonna get a bullet sizer for these remaining bullets. See if that helps. But I remember using these bullets as loaded Ammo causing the same problem. I’ll do 20 to see if they smooth out.

I remember the fouling last time at the range I couldn’t chamber a round. Had to clean the chamber too.


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