Flat base vs boat tail question in 300 blk

[DngBat7]

So I went to the range with new gun. I shot 2 different bullets. This is a fun gun and a cheap gun and was not expecting much. The first rounds I shot were magtech 123gr. The grouping was what I was expecting from this gun. About 1”- 1.5” at 50 yards. Figured that was not bad for a 12.5” barrel 1/8 twist with a 4x scope. What I expected. So the next Bullet I bought for testing was of the walmart shelf Remington 220gr subsonic. Did not know what to expect. With little to no effort, it shot 3/8 - 1/2”, 5 shot group at 50 yards. I was shocked! And it consistently did that. I was not planning on reloading seeing this was a 300 blackout for fun with a factory barrel, but now....

So here is the question. I was curious what the powder charge was so I took one of the 220gr bullets that shot well apart to weigh powder and it was a open tip flat base which I guess I could have read on the box. But I am used to reloading hpbt on my 6.5. So i was a little suprised. So now wanting to reload for this gun, I was gonna buy 220gr smk hpbt, but realized may they would not be as accurate in the short range ????

I have no idea what the answer would be for this, would love to hear from some benchrest guys. The bullet in the Remington 220gr was not a match bullet by any means.

 

[DngBat7]

To make it simple, which is more accurate at 100. Flat base or boat tail. Or is it a wash? Just figured you benchrest guys use flat base for a reason

 

[dcali]

That's not a question you can really answer definitively. As a rule of thumb, shorter, more compact bullets are more accurate, but differences in tolerances, twist rates, and overall design can impact that as well. In reality, you need to just try them when they're similar. I'd be comfortable saying a 112 grain flat base shot out of a 18 twist is going to be more accurate than a 240 boattail shot out of an 8 twist, but that's a pretty dramatic difference.

 

[ClassCat]

Flat Base bullet have larger pressure rings by as much as .0005-.0007 where as a HPBT could be only .0002-0003 over the caliber. You are creating higher pressure without changing the load, but it sounds like the gun likes it. Don't Argue with it, give it what it wants.

 

[Liven The Dream]

2 Cents ?
I have a Custom Made .270 Hunting Rifle .
It flat shoots Flat Base Bullets better than any other.
I have taken game at 500 plus yards ...
I just accepted the fact.
Have Fun .

 

[Tim Singleton]

Turn some 220 gr boat tails around backwards for your subsonic loads

 

[chkunz]

Boat tails are used to improve ballistic coefficient and do nothing positive for accuracy.

 

[DngBat7]

Turn some 220 gr boat tails around backwards for your subsonic loads

I don’t know seeing it has to feed over m4 style feed ramps

 

[DngBat7]

Does anybody know who makes a really nice flat base bullet 220gr?

 

[#40Fan]

I've never seen one. Was there a cannelure on the 220?

 

[Lone Hunter]

Here is a sample of just a few. Google them and I bet you find a lot more.

https://www.midsouthshooterssupply.com/dept/reloading/rifle-bullets/-point-308-dia/220-gr

 

[Twicepop]

From what I've read, a boat tail bullet will not totally stabilize (go to sleep) until the 300 yard point. I don't have the necessary equipment or a place to shoot beyond 100 yards to verify that. Also from what I've read most if not all bench rest competitors use flat base bullets in matches out to the 300 yard point because of that.

 

[DngBat7]

I've never seen one. Was there a cannelure on the 220?

The Remington 220gr umc off the shelf at Walmart ammo has them. I pulled the bullet apart, and it was a flat base bullet. Which I knew where they got them from

 

[rebel]

I'm not sure that bullet is available as a component. As said, there are other choices. The 220 round nose is very accurate to 100 yards subsonic. Some have feed issues in ARs however. I like the 220 MK. It feeds well and I have had excellent accuracy with it, again subsonic. The boat tail really doesn't come into play as much below 1100 fps. If you look at the 200 gr. Lapua subsonic bullet, you will get what Tim said about loading backwards.
I don't do it but it is a more optimum shape for subs. BTW - pistol gas AR? N110 is your friend

 

[MGYSGT]

Ask yourself. What bullets do the Benchrest shooters use at 100 and 200 yards. Flat base bullets is their choice.

 

[dellet]

Target or hunting? A number of the cartridge specific bullet designed for subsonic use are flatbase, but don't really have the accuracy of a match bullet.

The choices for a heavy flat base will are limited. The one in the Remington UMC was designed cartridge specific by Remington and has never been offered as a component.

The Remington Match subs use a 220 SMK, the chamber was actually designed around that bullet to be loaded at 2.260" and be .010" off the lands. Most of the SMK's have the same profile so they all work well.

You might enjoy the 120 UMC supers. Another bullet designed for the cartridge that is a flat base MOA +/- 1/4 is the norm.

As far as bullet choice, flat base or boat tail for subsonic shooting is just a choice. The SMK, Vmax, ELD, Berger and Lapua lines have all proven to be MOA capable. Anything jump friendly. Generally it's vertical stringing that gets hard to handle. 10 fps is generally good for an inch at 200 yards at 1000 fps. A 230 Berger is a very good target choice

For supers, plenty of flat base bullets 150 grains and under if you're after max velocity. You're talking around 20 grains capacity to the base of the neck. Why waste the space on a tail if you aren't shooting past a few hundred yards? Fill it with powder.

You never said what you are shooting. In an AR you are more limited in bullet choice because of feeding. Hand fed actions, anything goes at almost any speed.