Bullets being inertia pulled while chambering

[ported45]

Thought I would start my own thread on this.

Started out that my Grendel reloads were growing in COL by 0.005" when fed from the magazine by either fully pulling the charging handle and releasing or just popping the bolt release to chamber up a round. Then came the Lee Factory Crimp die. Slowly adjusted from recommended lighter crimp to "make your own deep cannalure" crimping. No dice. Still bullets sliding FORWARD in the cartridge neck the same 0.005". I was gravitating toward replacing the standard carbine spring that came with my lower with a reduced power recoil spring.

I think that I had read somewhere on here that somebody was increasing their tension by sizing without the expander ball. I tried that and immediately the COL growth stops at only 0.002".

I am going to give reloading a go by just sizing with the expander ball out and see what happens.

I will report back when I eventually get around to shooting again.

BTW- thanks for everyone's input on the other threads where I have thrown this out there!!

[LRRPF52]

What die are you using to size your cases, because in the past 9 years of regularly loading for this cartridge, I've just not seen this issue.

I've been using Hornady New Dimension™ dies.

[Klem]

Ported,

Given your concern about this on the other thread I used the Hornady gauge to check several hand-loads by ejecting from the chamber without firing. None of the bullets have moved. I have to agree with 52', your situation is not normal and it all boils down to not enough neck tension in an auto loader.

Removing the expander is a poor-mans version of a bushing die. The expander ball expands the inside neck out a little more than what the top part of the die has crushed. I use a Forster without the expander which leave's the neck .0035" less than when loaded with a bullet. That's good enough to keep bullets from moving.

[LRRPF52]

I should have mentioned that I polished my expander football in my sizing die as well, since they often come with tooling marks perpendicular to the range of motion and can use some TLC in that regard.

If I were making dies, I would look at tumble-polishing my expanders, but that would add cost as well.

[Mad Charlie]

Thought I would start my own thread on this.

Started out that my Grendel reloads were growing in COL by 0.005" when fed from the magazine by either fully pulling the charging handle and releasing or just popping the bolt release to chamber up a round. Then came the Lee Factory Crimp die. Slowly adjusted from recommended lighter crimp to "make your own deep cannalure" crimping. No dice. Still bullets sliding FORWARD in the cartridge neck the same 0.005". I was gravitating toward replacing the standard spring that came with my lower with a reduced power recoil spring.

I think that I had read somewhere on here that somebody was increasing their tension by sizing without the expander ball. I tried that and immediately the COL growth stops at only 0.002".

I am going to give reloading a go by just sizing with the expander ball out and see what happens.

I will report back when I eventually get around to shooting again.

BTW- thanks for everyone's input on the other threads where I have thrown this out there!!

I had exactly the same problem, and solved it just like Klem did. I also use Forster dies.

[ported45]

What die are you using to size your cases, because in the past 9 years of regularly loading for this cartridge, I've just not seen this issue.

I've been using Hornady New Dimension™ dies.

I'm using the Hornady dies, too.

[ported45]

Also forgot to mention that Hornady Black factory rounds showed the same 0.005" forward movement.

[Texas]

Also forgot to mention that Hornady Black factory rounds showed the same 0.005" forward movement.

That is pretty important to the discussion and moves it out of a reload problem. Are you using a rifle or carbine spring? What weight buffer are you using? What type BCG, AR15, M16, low mass, etc.?

[Mad Charlie]

That is pretty important to the discussion and moves it out of a reload problem. Are you using a rifle or carbine spring? What weight buffer are you using? What type BCG, AR15, M16, low mass, etc.?

Yes, this is important information. Please fill us in.

[HuntTXhogs]

I’d sure like to know the answer here : my bullets move forward as well when being chambered.

I never thought to try them in another Grendel I just ASSumed it was my reloading technique.

Do you have another Grendel to try them in that’s the tell tale....

[ported45]

That is pretty important to the discussion and moves it out of a reload problem. Are you using a rifle or carbine spring? What weight buffer are you using? What type BCG, AR15, M16, low mass, etc.?

Standard carbine spring and buffer. M16 bcg.

I think this is a lot more common than people think. Most either fire everything they have in the mag or don't think about measuring their rounds that have been chambered and not shot.

[ported45]

I’d sure like to know the answer here : my bullets move forward as well when being chambered.

I never thought to try them in another Grendel I just ASSumed it was my reloading technique.

Do you have another Grendel to try them in that’s the tell tale....

I have another upper on the way. The BCA upper that I was using had been replaced three times for short throats and the last one I got (not short throated!) gave me worse groups than the two I tried with short throats! 5.25" group with Hornady Black.

BCA sent me a UPS postage print to return the upper for a refund. I quit after 4!

[Mad Charlie]

Both of my rifles do it. AA barreled upper and Satern barreled upper.
Satern upper has Spikes T3 buffer with std. spring, AA upper has Spikes T2 with std. spring.
Both have M16 carriers.

Haven't measured factory rounds yet, also plan to measure my 5.56 rifles with M855 and M193.

[sneaky one]

I hone the expander, to get 4k, and take it out to get 5k of neck tension from my Forster die. Nothing moves, brass lasts and lasts,,, Lapua brass is the way to go.


I use a Noveske H2 carbine buffer, std. spring. Works in the 20" & the 16'.

[A5BLASTER]

So I have been following this for a bit and decided to take all three of my grendels and see if I could get one of them to make this happen with factory ammo and my handloads.

One lower has jp lowmass bcg and jp scs
Second lower has PF m16 profile bcg and gen 2 scs
Third lower has jp low mass bcg and Tubbs extra power carbine spring and h3 buffer

Tested this with 5,10,24 and 26 round mags made by elander,cpd,asc and the old cp company plus some 5 round pmags.

I used eld-m,sst,fusion,tnt,nbt,ttsx all factory loads plus my 85 grain Trex handloads.

I cycled 5 of each round two times through each mag in each lower and measured each round before and after.

Not one round changed messurment, no matter how I tryed it I couldn't make my gear do what you say yours is doing.

Could it be your just not getting enough neck tention and or getting enough crimp on your loads?

[A5BLASTER]

Are could it be your case mouth is contacting the front of the mag when cycled and that is causeing the issue somehow?

[Sticks]

It would be odd for a case mouth rubbing on the mag to cause inertia movement longer.

A member on another forum has been having the same issues (just started reloading) with bullet/COAL growth. Factory ammo is actually worse than his, but factory ammo gives him singe digit SDs and all his are 20s and up when auto fed. If he single feeds his handloads, rides the charging handle forward and uses the FA to go into battery, then his handloads drop into the singles. He's been doing the identical things here, even a Lee factory crimp die so tight it deforms the bullet.

[A5BLASTER]

I don't know Sticks.

All I really know is I couldn't get none of my fear to cause this to happen, so basically just trying to see if I could get it to happen and help come up with a reason why and a fix that might help.

But I do know for a fact that a poor mag that feeds like junk will knock bullets lose from the case.

The first cp defense 26 round mag I tryed feed so poorly that it would slam the case mouth into the front of the mag and the feed ramps so bad that it seated some so hard and deep into the powder charge I simple throw them away and the rest I could pull out and reseat the bullets by hand in the case.

[ported45]

I don't know Sticks.

All I really know is I couldn't get none of my fear to cause this to happen, so basically just trying to see if I could get it to happen and help come up with a reason why and a fix that might help.

But I do know for a fact that a poor mag that feeds like junk will knock bullets lose from the case.

The first cp defense 26 round mag I tryed feed so poorly that it would slam the case mouth into the front of the mag and the feed ramps so bad that it seated some so hard and deep into the powder charge I simple throw them away and the rest I could pull out and reseat the bullets by hand in the case.

I thought of the mags, too. Smoothed every edge on my C Products 10 round and even used a PMag 10 round to hold 3 rounds and attempted the feeding. EXACT same results as before.

As stated before in this thread, done everything I can think of to clean brass, use Hornady ND dies, even used Lee FCD from practically no crimp to the point of deforming the bullets into having a cannalure ring where there wasn't one. No change, still 0.005" of COL length INCREASE.

The only thing that has made any difference was to size the brass without the expander and the bullet now only moves 0.002", but is still moving nonetheless!

Even tried a very mild Lee FCD crimp with the brass sized without the expander and the bullets started slipping MORE again!!!

Now the BCA upper has gone back to the hell from whence it came. I will start this whole thing over again whenever I get another upper. Hopefully I will be as lucky as most of you next time.

[A5BLASTER]

I thought of the mags, too. Smoothed every edge on my C Products 10 round and even used a PMag 10 round to hold 3 rounds and attempted the feeding. EXACT same results as before.

As stated before in this thread, done everything I can think of to clean brass, use Hornady ND dies, even used Lee FCD from practically no crimp to the point of deforming the bullets into having a cannalure ring where there wasn't one. No change, still 0.005" of COL length INCREASE.

The only thing that has made any difference was to size the brass without the expander and the bullet now only moves 0.002", but is still moving nonetheless!

Even tried a very mild Lee FCD crimp with the brass sized without the expander and the bullets started slipping MORE again!!!

Now the BCA upper has gone back to the hell from whence it came. I will start this whole thing over again whenever I get another upper. Hopefully I will be as lucky as most of you next time.

Just a side thought but I would be willing to hazard a guess maybe the bca barrel had a short throat and was catching enough of the bullet to pull it forward when it was extracted.

I know the bca barrel I had for a total of 4 days had a very short throat, no ammo even my handloads that are 2.200 oal with the short 85 grain trex would chamber without hitting and getting marks from a short throat.