Polymer tip ammo in your AR? [Archive]

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5.56Geo

08-01-19, 10:51

I am having issues with the polymer tips breaking off during chambering. The rifle is a BCM 16" mid-length with a BCM bolt carrier group. The ammo is Hornady VMAX 55 grain handloads. Is there any secret to get polymer tips to function reliably in an AR or is it just the nature for them to break off due to the violent chambering of the cartridge? Thanks.

markm

08-01-19, 11:01

Never had any issues with tipped ammo in an AR. Two things come to mind:

1. Your bullet seating depth may need to be changed (probably shorter if you have OAL set to 2.250") or...

2. There's a low probability that there's an issue with the upper. i.e. miss-aligned barrel extension, etc.

(also... PMAGs have a higher feed angle than USGI, so that might help it you're not already using them.)

ST911

08-01-19, 11:47

twm134

08-01-19, 15:06

Has this upper ever worked with plastic tips? If this is a new batch of bullets they may be defective.

lsllc

08-01-19, 15:39

I have fired over 20,000 rounds of V-Maxes through ARs. Never a broken tip. It’s likely a COAL problem or your bullets are old and have become brittle. That isn’t uncommon with polymer tips, especially with light exposure.

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markm

08-01-19, 18:48

Has this upper ever worked with plastic tips? If this is a new batch of bullets they may be defective.

This is a possibility. We had some Nosler Accubonds that had defective/brittle tips. I doubt this is the case with Hornady, but you never know.

5.56Geo

08-01-19, 20:26

Thanks guys for the replies...

A little more information:

1. COAL is 2.25” on these hand loads
2. I have only used Magpul PMAGs magazines
3. I have never shot any Polymer tipped ammo through this BCM
4. These projectiles are about 3 years old but have been stored in a sealed container in the reloading room

I did try and break the tip off a few unloaded projectiles which proved to be a bit difficult. I will re-seat these a little shorter. Where should I start?

Thanks again guys. My apologies to those of you that have heard/seen this topic umpteen times. I come in peace and appreciate and recognize the wealth of knowledge found here so I yield to you with the upmost respect.
-Geo

lsllc

08-01-19, 20:31

I would try them at 2.20-2.22” range. Be sure that isn’t going to increase your pressure.

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twm134

08-01-19, 21:25

Factory Hornady ammo loaded with 55 V-max measures about 2.225". Maybe try that COAL.

markm

08-02-19, 12:23

I would try them at 2.20-2.22” range. Be sure that isn’t going to increase your pressure.

I agree. Pressure shouldn't be an issue unless you're really running a stout load already. That extra jump to the lands bleeds off a sliver of initial pressure, so I'd just spin that seater down and give it go.

lsllc

08-02-19, 12:26

I agree. Pressure shouldn't be an issue unless you're really running a stout load already. That extra jump to the lands bleeds off a sliver of initial pressure, so I'd just spin that seater down and give it go.

Yup. Usually it’s not a problem unless it’s super-deep. I have seen pressure go up with this process, but typically they were compressed at the longer coal.

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markm

08-02-19, 15:12

I ran two identical loads with the exception of the bullet... 1. was 77 gr OTM, and 2. was 77 gr TMK. The TMKs seat much deeper to get them to mag length. But when I chrono'd both of them, I was shocked to see almost identical velocities. I expected to see a boost on the deeper seated bullet, but it wasn't there. Kind of interesting to me.

5.56Geo

08-03-19, 13:07

Thanks guys! Problem solved...

I changed the COAL to 2.20” and was able to shoot 50 rounds with no broken tips. One 10 round magazine was a mag dump with no issues.

-Geo

lsllc

08-03-19, 13:15

Thanks guys! Problem solved...

I changed the COAL to 2.20” and was able to shoot 50 rounds with no broken tips. One 10 round magazine was a mag dump with no issues.

-Geo

Awesome. Glad it solved the issue for you!

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markm

08-03-19, 13:26

Nice! :D

ST911

08-03-19, 18:16

Good info for the knowledge base. Thanks OP.

Uni-Vibe

08-04-19, 16:00

I had a Mini-14. They are said to "feed anything. " Domeone gave me a box of Hornady plastic tips. It was dreadful. Tips shattered and rounds failed to feed. Maybe M4 feed ramps are better, but I'd be careful in a duty gun