Negative effect of crimp on Barnes TSX/TAC-X?

[rocsteady]

I did a search and see that there is some disagreement on whether to crimp the Barnes TSX-M/LE TAC-X (same round according to Barnes technical support; just a different name).

I found that like others, it does move the bullet slightly and makes it tough to stay right near the 2.240 COAL (62g bullets), but does it have a negative effect on anything? Also, with that being said, is there any problem if some completed rounds are measuring 2.239-2.244?

Thanks, sorry if this is somewhere already posted, couldn't find it this morning.

[Coal Dragger]

Seating depth variances that small will have no effect on the safety of the round from a standpoint of pressure. So shoot them, and see how they do. There is a good chance that variances as small as you are seeing won't make much difference where accuracy is concerned either.

[Ironman8]

The above is correct. Seating depth changes don't affect pressure on bottleneck cased ammo as much as it does on straight walled (especially pistol) cased ammo.

Also, since the Barnes TSX is a long bullet for it's weight, you are most likely running a compressed load. Well at least I am with 70gr TSX and Varget. But if you are, the powder along with good neck tension should keep the bullet from any kind of setback caused by feeding...which I've yet to see happen on a normal bolt cycle/strip/load process. In fact, you'll notice that OAL will grow very slightly each time you chamber a round.

So in short, no, you don't necessarily need a crimp nor will a .005" difference in seating affect anything. Just an FYI, don't overdo it on the crimp. Bullet should rely more on neck tension than crimp to stay in place. You can actually loosen neck tension with a heavy crimp in some cases. I just keep it light to uniform up the case mouth to give it a good "seal".

Btw, did you ever find any powder?

[rocsteady]

Gentlemen, thanks for the responses, puts my mind at ease.

Ironman8, yep, I did find powder. Paid too much for it on gunbroker.com but just didn't want to wait any more.

[Snake Plissken]

In an AR-15, you ought to seat to what the magazine allows. If your act of crimping is changing the seating depth you are over-crimping. You should not require any crimp on the TSX bullets or any others in .223. COAL is only important for ensuring clearance in magazines and feeding. Your true seating depth is determined by measuring from the ogive of the bullet. You can determine the max COAL in your rifle using the dowel rod method...or a hornady OAL gauge (flimsy and overpriced for a little more precision). From that you'll find that the throat of your rifle is going to allow a COAL with what bullet you're using which exceeds the magazine allowance of your rifle.


Since you're presumably measuring tip to case head for your COAL readings, 0.005" variance in meplat is quite reasonable. Crimping your rounds will have far more of an effect than a few thousandth's difference in seating depth.


If you're getting setback, either you've lubricated the interior of your case neck or your neck mandrel in the die isn't the correct size. Whenever loading anything other than cheap M193 crap, I put a .22 cal brass cleaning brush in a cordless drill and briefly spin it inside the case necks. You just have to be consistent about it. The friction of the interior neck surface and the small difference in size will be plenty to keep it in place.


If I don't have to crimp 180 gr bullets in 308 for my FAL, you shouldn't have to for a 223 AR-15.

[rocsteady]

Any way to test the round either after crimped or not, to see if it's being held in the case properly?

[Ironman8]

Any way to test the round either after crimped or not, to see if it's being held in the case properly?

Make a couple dummy rounds (no powder or primer, and for the sake of testing, one with a crimp and one without), load into a magazine and chamber the round by pulling the charging handle back and letting go completely (as opposed to using the bolt catch). Measure OAL before and after each chambering.

I typically chamber the same dummy round 3 times and record all OAL changes (usually it will grow). I don't have the numbers off the top of my head as far as the results of my tests and what I consider acceptable bullet movement, but IIRC, if you can keep it under ~.003" per chambering, then you should be ok.

[rocsteady]

Make a couple dummy rounds (no powder or primer, and for the sake of testing, one with a crimp and one without), load into a magazine and chamber the round by pulling the charging handle back and letting go completely (as opposed to using the bolt catch). Measure OAL before and after each chambering.

I typically chamber the same dummy round 3 times and record all OAL changes (usually it will grow). I don't have the numbers off the top of my head as far as the results of my tests and what I consider acceptable bullet movement, but IIRC, if you can keep it under ~.003" per chambering, then you should be ok.

Very interesting, I will try it tonight. Thanks again.

[rocsteady]

Did "3 chamber test" last night and found the one with the crimp moved a total of between .001" and .002" where the non-crimped one moved a total of .001 if at all after being chambered three times.

Not what I was expecting but convinced my that I don't need to crimp 'em anymore. Outstanding information.

God bless the interwebs, it's like having an instructor in your house. Best part is I don't have to pay Ironman8 by the hour.

Thanks Bro.

[SkyPup]

I have never crimped my .223 Barnes 70 or 62 grain handloads and have never experienced a problem with setback or anything else with hundreds of rounds utilized.

They do just barely fit in the magazine though....