LMT enhanced bolt/carrier question

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dellet
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Re: LMT enhanced bolt/carrier question

Post by dellet » Tue Nov 17, 2015 1:34 pm

steven11b wrote:Well I guess there are many variables so I'll just shoot alot of these supers like I said to get a solid break in. Then I'll move to testing out subs. I am really hoping this bcg helps with gas mitigation as I use the standard novekse gas block. Plus the amount of money I invested in it!
The main thing would be to not change any load that you already have or there will be no way to judge if the BCG made a difference.

I changed in the middle of load development and that confused the issue. I know it helped and worked as advertised for supers, but they really don't make any claims for advantages for subs.

As for being able to run 175 grain bullets, it should not make a difference. I am working on bullets under 150 grains right now.
300 Blackout, not just for sub-sonics.

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steven11b
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Re: LMT enhanced bolt/carrier question

Post by steven11b » Tue Nov 17, 2015 3:03 pm

I will only be able to compare speeds and sound level as the upper was changed from a side charger with slots milled on both sides to a standard upper, so the gas level noticed by the shooter won't be comparable.
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Re: LMT enhanced bolt/carrier question

Post by 2manyToys » Wed Aug 07, 2019 12:26 pm

I know....holy necro thread, but I was wondering if there were any updates on this EBCG? I'm especially interested in how it work with fast pistol powders used with subs.

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Re: LMT enhanced bolt/carrier question

Post by Dr.Phil » Thu Aug 08, 2019 10:33 am

If it works with your port size / barrel length, powder selection has very little impact.
The fastest pistol powder that I've used for subs and still had proper function is AA#9.
(I rarely use the powder anymore due to it not having good case fill for subs and rapid pressure spikes for supers.)

I personally don't own any uppers without the LMT eBCG.
Just finished a 6.5 Grendel / .264 LBC-AR build and custom ordered a barrel just so I could use the 7.62x39 LMT eBolt.
Provided the barrel maker with my bolt and paid extra for them to head space off of the LMT eBolt.
(The barrel manufacture tried to talk me into a different bolt since they were not familiar with the LMT eBolt.)

The funny thing is that the LMT eBCG costs more than a lot of complete upper receivers.
I find that the benefit is worth the cost of admission.
In addition to a major increase in reliability, the added delay helps with both accuracy and load development.

If you haven't seen it, Chris Bartocci made a great video about Enhanced BCGs.
(Chris is the author of "Black Rifle II: The M16 Into the 21st Century")
https://www.youtube.com/watch?v=HZkK70Miz60
https://www.youtube.com/watch?v=18A-9Q__nNY
(The second video goes over the Surefire eBCG designed by Jim Sullivan and Jim personally praises the LMT eBCG.)
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Re: LMT enhanced bolt/carrier question

Post by dellet » Thu Aug 08, 2019 9:08 pm

The only “problem” I have encountered using the eBCG with fast powders is an increase in velocity when suppressed when compared to a regular BCG. If the load is developed with a regular, it will pick up as much as 40 fps with the enhanced.

I actually think it might help cycling, but don’t have enough data to support it.
300 Blackout, not just for sub-sonics.

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Re: LMT enhanced bolt/carrier question

Post by Dr.Phil » Fri Aug 09, 2019 8:16 am

dellet wrote:
Thu Aug 08, 2019 9:08 pm
The only “problem” I have encountered using the eBCG with fast powders is an increase in velocity when suppressed when compared to a regular BCG. If the load is developed with a regular, it will pick up as much as 40 fps with the enhanced.
I concur with this.
The unlocking delay adds just enough time for a more complete burn of the powder.
Shouldn't present as a huge issue, but if you are sharing loads among multiple platforms, performance will swing significantly.

The condition that creates an issue with the LMT e BCG is Gas Volume / Dwell.
That is why they do not recommend using it with anything shorter than 14.5" in 5.56.
I took a gamble with my 10.5" 300 BLK build in 2010.
Fortunately, 300 BLK gas setups are engineered to mimic standard 5.56 carbine gas signature.
(If it wasn't designed that way, that is what the net end result is regardless.)
The LMT eBCG was born out of a RFP from SOCOM for SOPMOD program to solve issues they were encountering with the 14.5" M4.
https://smallarmssolutions.com/home/lmt ... lt-carrier

Once again, well worth the price of admission.
- Superior metallurgy in the bolt
- Redesigned bolt lugs
- Fully supported bolt face
- Lobster tail extractor
- Slower unlock time
- The ability to function while fully fouled
These are the features that keep me coming back to this product.
Just wish the price and availability were better.
(LMT only does production runs a couple times a year.)
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Re: LMT enhanced bolt/carrier question

Post by 2manyToys » Fri Aug 09, 2019 10:14 pm

Thanks for the detailed information. Are you using semi or full auto bolt carriers?

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Re: LMT enhanced bolt/carrier question

Post by dellet » Sun Aug 11, 2019 8:41 pm

2manyToys wrote:
Fri Aug 09, 2019 10:14 pm
Thanks for the detailed information. Are you using semi or full auto bolt carriers?
Mine are FA and buffered accordingly for pistol or carbine.
300 Blackout, not just for sub-sonics.

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Re: LMT enhanced bolt/carrier question

Post by Dr.Phil » Mon Aug 12, 2019 8:33 am

2manyToys wrote:
Fri Aug 09, 2019 10:14 pm
Thanks for the detailed information. Are you using semi or full auto bolt carriers?
I use Full Auto carriers in my 5.56 & 6.5 Grendel.
The 300 BLK has a Semi Auto carrier.
Reason being, I had the SA carrier in my 5.56 and wanted the extra weight.
(Bolt stayed with the upper in order to maintain optimal headspace.)
Last edited by Dr.Phil on Fri Aug 16, 2019 1:40 pm, edited 1 time in total.
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Re: LMT enhanced bolt/carrier question

Post by Dr.Phil » Fri Aug 16, 2019 1:40 pm

Just a quick update on function / compatibility.
On my new 6.5 Grendel / 264 LBC-AR build, 100% reliable function with the LMT e-BCG.
SPEC:
LMT FA Enhanced Bolt Carrier
LMT 7.62x39 Enhanced Bolt
H2 Carbine Buffer w/ Standard Buffer Spring
X-Caliber 264 LBC-AR Chamber, 20" Light Weight Barrel, Intermediate Gas System
Noveske Low Profile Gas Block
100% function with bare muzzle, with TBAC 30P-1, and SRT Universal Typhoon Suppressors
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