Do you need to chamfer if using BT?


January 2, 2012, 10:10 PM
For .223 FMJBT, they seem to seat the same with or without a chamfer inside the mouth.

Is there any reason to put the chamfer there if I'm only using boat tails?

I use the Lee factory crimp die too if that matters.

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January 2, 2012, 10:54 PM
I chamfer after trimming regardless of what bullet is being stuffed in the case. It is needed to clean up the inside of the case mouth.

Chamfering new brass is not a bad idea to clean it up. but I will admit a boat tailed bullet will easily seat with out.

January 2, 2012, 11:02 PM
I agree, I ream and chamfer regardless of which bullet type being used. I can buy factory ammounition if I want run of the mill, or I can reload with precision methods if I prefer to shoot the best.
I also like to eliminate as much wear and tear on the chamber's as possible, and reaming and chamfering plays an important part.

January 3, 2012, 10:07 AM
For .223 FMJBT

Sounds like you're just loading some blasting ammo; I wouldn't (I don't) bother. If your trimmer is doing a good job, it should leave a pretty clean cut. If you had said you were loading HPBT's, I would agree w/ other on the chamfer.

Just my $0.02. That time would be better spent loading another (un-chamfered) 600rds.

January 3, 2012, 01:05 PM
So the chamfer inside the mouth (not the deburr for the outside) plays a role in overall performance/consistency? I thought its only function was to help the base of the projectile get into the mouth. Not that it takes long or is a difficult task, just didn't want to be doing it if it served no purpose with my rounds.

January 3, 2012, 01:24 PM
Burs or sharp edges inside the case mouth have to go somewhere when you crimp them.

Only place they can go is into the bullet jacket & core.

That isn't helping the FMJ-BT bullet accuracy any.
And they need all the help they can get already.


January 3, 2012, 02:09 PM
chamfer- Load 10 with chamfer & 10 no chamfer, shoot 4 groups, 5 shots each @ 100 scoped or 50 yds iron sights, report back. My guess, no difference in accuracy with the fmjbt bullet.

January 3, 2012, 02:25 PM
I personally make no exception, and even get a bit anal about how I prepare my brass to eliminate variables that can present. The lip or ridge left by triming on both the inside and outside can be quite excessive, which I again personally feel could cause chamber wear, and even pinching during firing?

I just did a test to see how much of a measurable difference is present without chamfering the inside edge after trimming. Depending on how much is being trimmed the lip is from + .003" to as much as + .008" at the mouth. That's too much of a variance for my taste.

January 3, 2012, 02:32 PM
I don't chamfer any of the rounds trimmed with my Dillon trimmer but not only are they bur free after being trimmed but go through 3 different expanders as well, before a bullet is droped into the case by the feeder.

January 3, 2012, 02:49 PM
I always chamfer. I don't know what I will be loading it with next time thru and if it is already chamfered I don't have to worry until it gets trimmed again.

January 3, 2012, 03:01 PM
It's quick, it's easy, and it's a good idea.

January 3, 2012, 05:14 PM
Reloading ,in my opinion, and we all know what's said about opinions, is as much about getting all you can from a bullet regardless of what it is to be used for. This is especially true with rifle loads. I always deburr, ream and champer every trimed case when loading for a rifle. But......I also ream the flash hole and the primer pocket on unfired brass prior to loading. To excess? Probably so. but that is just me.

January 3, 2012, 05:40 PM
Do you need to chamfer if using BT?

I chamfer all my cases after trimming. However, I recently started "selectively trimming." I measure every single case, and if it's over 1.755, it gets trimmed/deburred/chamfered. I don't trim 1.755 or under. (Haven't seen one under 1.748 yet, so no rejects for short.) This saves a TON of time and effort.

January 3, 2012, 09:27 PM
If you ARE going for max accuracy then chamfering will help reduce the chances of scraping the outside of the bullet when inserting it into the brass. This will help your accuracy, How much is always up for debate.:scrutiny: I used to do all sorts of things to my brass to make it work better, now I do not bother with a lot of things with blasting ammo---cleaning primer pockets, chamfering inside, cleaning brass well, seperating by weight/head stamp, weighing bullets, etc etc. They are still more acurate than I shoot with my 223/5.56.

Hondo 60
January 3, 2012, 10:19 PM
When I trim, I chamfer.
Doesn't matter what bullet I use.

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