Bullet Deformation Effect on Accuracy

[k Squared]

I don't expect "Bulk" bullets to be top quality, but this deformation seems to be excessive.



It's a little difficult to see how big the bulge is, but this picture shows that the bullet won't sit flat on its base.



I've been told that this sort of thing won't have a significant effect on accuracy out to 100yds.

That do the experts have to say?

[nemesiss45]

I dont think it will make a huge difference. it may be on the extreme heavy end of the spectrum of the bullets in your box, but cheap bulk bullets will always vary.

I wouldn't load that for accuracy, but it should be fine for plinking.

you should do an experiment, and load it, mark it, then shoot it with a group of "good" bullets and see how far out of the group it is, if at all.

you should also weigh it to see how far off it is from what it should be

[Sharkbite]

I use "blems" from Powder Valley all the time as my plinking/practice round in short barrel guns. 9" 300blk. 12" 223. I also use blems in my 308 subsonic loads (short range because of drop)

I feed my sniper rifles firsts

I dont think the blems would make much difference at 100yds unless your shooting for ultra accurate match type stuff

Even if the blems cost you 1/4 MOA. Most gun/shooter/load combos wont notice or care at 100

If you plan on reaching out to 500 or 1000 maybe blems arent the answer

For me
Blems for mass loading and close range stuff
Premium for distance and ultra precision work

[44 AMP]

Deformation to the nose of a bullet has little effect on its accuracy at short to moderate ranges.

Deformation to the base of the bullet does have an effect, and sometimes a large one noticeable at short range.

Essentially, something that throws off the weight/balance of the nose of a bullet doesn't matter much, if any. Anything that throws off the weight/balance of the base of a bullet matters a lot.

When you buy the cheapest stuff you can get, you almost always get what you pay for.

[Bart B.]

With those bullet bases so distorted, gas will not blow out evenly around them as they leave the crown on the muzzle. They'll start tumbling a few inches down range and keyhole through targets 5 to 10 yards away.

You may not be able to seat some in case necks good enough to chamber the round.

Use them for paper weights on Post-It notes and postage stamps.

[Arub]

Reading this post I just learned something.

A while back, Myth Busters did a piece on the effects of distorted pistol bullets. They distorted the head in several ways including cutting out a good section of it. Results showed no distortion in trajectory/accuracy (small sampling). I took this as pretty near any distortion would not be an issue.

Previous posts add to this. Myth Busters only studied effects on the bullet nose, not the base so, if anyone else got the wrong impression the previous posts should give them, like me, something to consider.

Thanks for the info.

[Jimro]

A deformed base is at best a non-called flyer, at worst it's a "where did that thing go?!?!?!"

Cull that bullet, it won't do you any favors for accuracy.

Jimro

[243winxb]

Expect 3" ten shot groups at 100 yds. Bullets look like 2nds in 55gr .224" diameter. Blasting bullets, not match. Great for machine guns.

[steve4102]

Armscor bullets maybe? If so, they usually shoot like crap even without the base deformation.

[k Squared]

nemesiss45,
You're right...this calls for an experiment to determine how much the accuracy is affected.
Of course, that assumes I could shoot a decent group with good bullets, and you know what happens when we ASSuME!

[44 AMP]

The experiment has been done, decades ago, by gun writers, I remember reading some, although cannot now remember just where or when.

Essentially, they drilled bullets to remove varying amounts of weight in different places. All variations in the nose of the bullet rarely did anything noticeable. Anything that unbalanced the base of the bullet resulted in flyers.

Go ahead and try it. It ought to be a fun day. Let us know if you have a different result. I don't think you will.

[Slamfire]

A bud of mine, at his gun club, was talking to a bench rest shooter. The bench rest guy showed him that you could absolutely mash the front end of a rifle bullet all to heck and it would go in the same hole. But, one tiny scratch to the base, and the bullet went out of the group.

I remembered that, and once in an XTC match, because of an interruption, I got an extra sighter. I was at 300 yards, sighting for prone RF. I took a 308 round, capped with a 168 SMK, took my leatherman tool, crushed the bullet tip, and using the wire cutter, cut the flat area at a diagonal. I then shot it, and it was a pin wheel "X".

The 22LR is a very old cartridge and I think the crimped base is a source of inaccuracy with this round. The crimp is absolutely where you do not want it, at the base.

[Bart B.]

.22 rimfire Eley and RWS match ammo with crimped in bullet heels used to shoot inside 1/2" at 100 yards all day long. The Russians made rimfire ammo that shot inside 3/8" at 100 yards all day long, too. Considering the muzzle velocity spread caused most of the group axis to be vertical, the crimp on this stuff was very consistant in grip and release else those bullets would not shoot as good ad they did.

Stuff these days ain't quite as good, but still remarkable for a lot of crimp on lead bullets. Eley's probably done the most tests with different styles and amounts of crimp on their match bullets.

[k Squared]

So...I get this great idea. Just melt the lead at the base of the bullet and it will solidify in a flatter (more symmetric) shape.
I borrow a Crème Brulee Torch from the kitchen and start cooking.



The torch melts the lead very quickly, but instead of a flatter base, I get a rounded base. Still, it looks much more symmetric.



The two bullets at the top of the picture have been melted. The two bullets at the bottom of the picture are "untreated"
Obviously, the proof will be in shooting the "treated" bullets, but I'd be interested in your predictions.
I am a little concerned about leading, with so much lead below the jacket.

[P-990]

I'd still segregate them into their own box or baggie with a note on them. They may not print to the same POI as the non-blemished bullets, though they may not be out-and-out fliers anymore either.

Reading about the deformation of bases versus tips made me smile. Reminded me of when I worked at a sporting goods counter. One year somebody came up with a special jag to prevent deformation of the polymer tips of the various sabot bullets. I laughed, and I explained how the tip doesn't matter (and isn't getting mashed as hard as the guys think). Still sold tons of them anyway.

As for blem bullets, depending on the blemish they may be a great deal. I spent one summer shooting up a couple thousand "seconds Nosler 77gr HPBTs in a .223. Won and placed at more than a few XTC matches that year. As I recall those bullets were only cosmetic seconds, slightly discolored and some of the tips were uneven.

[musher]

I highly recommend "Rifle Accuracy Facts" by Harold Vaughan.

He systematically explores and attempts to measure the effects of a number of factors on rifle accuracy. One section is a study of the effects of projectile deformations of various types.