u/Blowback9

YouTube video explaining the DBC Insert and potential issue/fix with using it in a 9mm bolt.

TL;DR: It MAY work if the rear of the DBC insert is flush with the rear of the bolt when installed and pushed all the way rearward. If not, the deadblow effect of the weight is severely limited, possibly to the point of being ineffective. It would need to be trimmed at the rear so it rests flush or below flush with the rear of the bolt to maintain the proper movement distance.

What's the advantage to using this in a 9mm AR bolt? There really isn't one. A 9mm blowback would still need a heavy deadblow buffer to operate safely. It would just convert the heavy weight in the bolt to a deadblow mass, adding more deadblow effect to what is already in the buffer.

This 2.6oz. deadblow weight is intended for gas-operated AR's and is designed to be paired with another 2oz. of deadblow mass in a standard AR buffer, giving about 4.5oz of deadblow mass - the same as what is found in an H3 buffer (or a KVP 10oz. buffer).

If paired with a solid 8oz. buffer, it would at least provide SOME deadblow effect, but only 2.6oz. worth (more than the Odin Works FRT buffer). Still, that may not be enough. Further testing would be required.

I'M BACK, BABY!

Testing the Odin Works H-FRT-9 (finally!)

Complete article with details and disassembly photo: https://blowback9.wordpress.com/2026/08/14/odin-works-h-frt-9-buffer/

TL;DR: It seemed to perform just fine. No bounce at the range. Tentative thumbs up for FRT use.

With only 2.1oz. of deadblow mass, bolt bounce could potentially be an issue, but in live fire high speed video testing there was no noticeable bolt bounce.

It's important to note that there WAS bolt bounce when bench testing using the bolt-drop test, but this is a "worst case scenario" for buffers and is not a indication of how it performs during live fire. Instead it lets us know that this deadblow mass is "closer to the edge" of bouncing compared to one that doesn't bounce during the bolt drop test, that's all.

FM has restocked their Foldyboi with RMB. 30 available right now. 20% off currently.

https://store.fm-products.com/products/fm-products-foldyboi-lwr-rmb-5397

I know some people have been watching out for them to be in stock.

I am not affiliated or compensated in any way. I do not sell anything. Just passing on in stock notification info I received in my email.

​

For 9mm AR using FRT and experiencing Dead Trigger/Light Strikes despite using a heavy deadblow buffer...

Reports back on the Extra Power (XP) Lee Springs firing pin (FP) spring replacements that I first suggested have been mostly positive. They seem to have fixed most Dead Trigger/Light Strike (DT/LS) problems. A few people are still reporting problems even with the XP FP springs. For you folks, I have identified even stronger FP springs that may fix it. These are the strongest I can find that will fit in the FP channels and don't get overcompresssed (very bad for spring lifespan.)

If ordering from Lee Springs: They have VERY HIGH shipping and handling unless the order is over $40. Ordering 5 springs costs the same as ordering ONE. A good idea may be to order 3 XP and 2 XXP (or vice versa) in case you need the stronger one to fix the DT/LS.

I am NOT affiliated, get NO kickbacks or income, and do NOT sell anything.

**Links cannot be posted in this sub, so go to the post in r/AR9 for the links. It's almost impossible to find the springs without direct links. Sorry.**

https://www.reddit.com/r/AR9/comments/1vdgp9s/updated\_firing\_pin\_spring\_suggestions\_for\_dead/

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Technicals:

Most 9mm bolts seem to have about L1 = 11-15oz., L2 = 23-30oz. with their stock included springs.

The UXCELL Amazon spring recommended for older FM bolts with weak FP springs is only L1=11oz., L2=25oz. Same as a standard spring. These are NOT RECOMMENDED for preventing DT/LS.

I have a older bolt with a firing pin spring that requires 100oz. at L2 and it works just fine with consistent ignition of standard primers. Anything under this should work fine.

The FM channel is dimensioned to use a 0.8" spring

• A normal FM firing pin spring gives about L1 = 15oz., L2 = 30oz.

• LC 026BC 08S in an FM bolt gives about L1 = 30oz., L2 = 50oz.

• LC O28BD 10S in an FM bolt gives about L1 = 50oz., L2 = 75oz.

The Outerwild and most other (Faxon, Angstadt, OSUSA, KVP, PSA, IDL, etc.) bolt firing pin channels are made for a 1" spring despite the factory supplying a 0.8" spring. 1" is the correct length for these bolts.

• An Outerwild firing pin spring gives about L1 = 11oz., L2 = 25oz.

• LC 026BC 09S in a Outerwild gives about L1 = 30oz., L2 = 50oz.

• LC O28BD 11S in a Outerwild gives about L1 = 45oz., L2 = 70oz.

For 9mm AR using FRT and experiencing Dead Trigger/Light Strikes despite using a heavy deadblow buffer...

Reports back on the Extra Power (XP) Lee Springs firing pin (FP) spring replacements that I first suggested have been mostly positive. They seem to have fixed most Dead Trigger/Light Strike (DT/LS) problems. A few people are still reporting problems even with the XP FP springs. For you folks, I have identified even stronger FP springs that may fix it. These are the strongest I can find that will fit in the FP channels and don't get overcompresssed (very bad for spring lifespan.)

If ordering from Lee Springs: They have VERY HIGH shipping and handling unless the order is over $40. Ordering 5 springs costs the same as ordering ONE. A good idea may be to order 3 XP and 2 XXP (or vice versa) in case you need the stronger one to fix the DT/LS.

I am NOT affiliated, get NO kickbacks or income, and do NOT sell anything.

For FM bolts (only!):

Standard XP: LC 026BC 08S https://www.leespring.com/product/compression-spring-lc026bc08s-stainless-steel (previously suggested)

**XXP: LC O28BD 10S https://www.leespring.com/product/compression-spring-lc028bd10s-stainless-steel (added - extra strong)**

For most others bolts (Outerwild, Faxon, Angstadt, KVP, OSUSA, PSA, IDL, etc.)

Standard XP: LC 026BC 09S https://www.leespring.com/product/compression-spring-lc026bc09s-stainless-steel (previously suggested)

**XXP: LC 028BD 11S https://www.leespring.com/product/compression-spring-lc028bd11s-stainless-steel (added - extra strong)**

---

Technicals:

Most 9mm bolts seem to have about L1 = 11-15oz., L2 = 23-30oz. with their stock included springs.

The UXCELL Amazon spring recommended for older FM bolts with weak FP springs is only L1=11oz., L2=25oz. Same as a standard spring. These are NOT RECOMMENDED for preventing DT/LS.

I have a older bolt with a firing pin spring that requires 100oz. at L2 and it works just fine with consistent ignition of standard primers. Anything under this should work fine.

The FM channel is dimensioned to use a 0.8" spring

• A normal FM firing pin spring gives about L1 = 15oz., L2 = 30oz.

• LC 026BC 08S in an FM bolt gives about L1 = 30oz., L2 = 50oz.

• LC O28BD 10S in an FM bolt gives about L1 = 50oz., L2 = 75oz.

The Outerwild and most other bolt firing pin channels are made for a 1" spring despite the factory supplying a 0.8" spring. 1" is the correct length for these bolts.

• An Outerwild firing pin spring gives about L1 = 11oz., L2 = 25oz.

• LC 026BC 09S in a Outerwild gives about L1 = 30oz., L2 = 50oz.

• LC O28BD 11S in a Outerwild gives about L1 = 45oz., L2 = 70oz.

​

The UXCELL firing pin spring will NOT prevent firing pin bounce! It's the same strength as a normal firing pin spring.

I'm posting this because I keep seeing people asking about using the UXCELL spring from Amazon as a replacement firing pin spring to prevent firing pin bounce with FRT's.

The UXCELL spring is only as strong as a STANDARD FIRING PIN SPRING. It's nothing special.

The UXCELL spring was only recommended for a short time as a replacment fix for older FM bolts that used a very weak firing pin spring. FM no longer uses these weak springs, so the UXCELL is now obsolete unless you have one of those older FM bolts with a spring only about as strong as a ballpoint pen spring.

The best option we have so far to prevent firing pin bounce with FRT is the LEE springs. Yes, they're expensive, but no one else sells these small springs in small quantities online. Buy 5 to avoid shipping/handling. 5 costs the same as buying 1, so at least you have spares.

See THIS POST for updated firing pin spring suggestions for firing pin bounce/Dead trigger/Light strikes, with links and details:

https://www.reddit.com/r/AR9/comments/1vdgp9s/updated_firing_pin_spring_suggestions_for_dead/

I am not affiliated or sponsored, and do not sell anything.

_______________________________________________

TECHNICALS:

Most 9mm bolts seem to have about L1 = 11-15oz., L2 = 23-30oz. with their stock included springs.

The UXCELL has L1 = 11oz., L2 = 25oz., so it's only as strong as a standard FP spring.

The LEE Springs XP springs give about L1 = 30oz., L2 = 50oz. while the XXP springs give about L1 = 45-50oz., L2 = 70=75oz.

Stacking tolerances - hammer/lever interference issue with Milspec hammer.

I was alerted to this problem/solution that someone had with the ARC and a Spikes lower, but this could happen with other setups or FRT's. I've seen this same exact complaint, but we never could figure out the root cause/solution.

The problem was bulged cases/OOBD, even in slow fire.

In some builds, the bolt may be held slightly out of battery by the lever if it's resting up against the hammer and the stacking tolerances are just right.

Essentially the lever was acting like a bridge between the rear of the cocked hammer and the bolt, holding the bolt slightly back. The fix was to reduce the material at the back/top of the hammer just a tiny bit where the lever rests, just enough to let the bolt go forward all the way. Too much could allow the lever to fall too far forward and get jammed, or allow the bolt to skip right over it.

Reducing the lever at the front top curve may also be an option, but hammers are easier to replace if it gets screwed up.

Hope this helps someone.

Just sharing to let everyone know. This is system-wide update for Reddit SFW subs unless restricted by the mods of a particular sub.

I just received feedback from Paul, the owner of Foxtrot Mike. In their testing (so far) FRT dead trigger/light strikes (DT/LS) in their 9mm AR's are fixed by using the double-strength Lee Spring firing pin spring.

I had to do a lot of analysis to figure out the probable cause of the dead trigger/light strike issue and to select new firing pin springs based on ID, OD, wire diameter, solid height, rate, and length (depending on the bolt's firing pin channel dimensions).

For FM bolts ONLY: Lee Spring LC 026BC 08S

FM is looking at the possibility of buying a bunch of the FM bolt spring version and providing them on the website at a very reasonable price for folks who have the DT/LS issue with FM bolts.

Do NOT try to use the FM firing pin spring in a different bolt and expect the same results!

The spring needed for most other bolts is DIFFERENT (longer) to get the same resistance. The FM bolt's firing pin spring channel is shorter. The shorter spring doesn't provide the same resistance when used in a bolt with a longer spring channel.

For most other bolts with the longer spring channel (Outerwild, KVP, PSA, Angstadt, Faxon, IDL, etc.) the following longer spring is necessary to provide double the resistance: Lee Spring LC 026BC 09S

ETA: As someone mentioned below, the original mfgr spring in the Outerwild/PSA/etc. is 0.8" like the FM original spring, however, the firing pin spring channel is longer internally. These bolts more closely follow the original Colt firing pin channel spec, which used a 1" spring. If the FM Lee Spring is used it "may" work, but produces significantly less spring pressure to counter the firing pin bounce. It's too short.

I chose the 1" spring to give double the strength while still working properly, not overcompressing, and closely matching the ID and OD requirements of the firing pin channel.

So, yes, I did really think this through and considered a lot of variables to come up with the specific spring choices I made for the different bolts.

I just received feedback from Paul, the owner of Foxtrot Mike. In their testing (so far) FRT dead trigger/light strikes (DT/LS) in their 9mm AR's are fixed by using the double-strength Lee Spring firing pin spring.

I had to do a lot of analysis to figure out the probable cause of the dead trigger/light strike issue and select new firing pin springs based on ID, OD, wire diameter, solid height, rate, and length (depending on the bolt's firing pin channel dimensions).

For FM bolts ONLY: LC 026BC 08S: https://www.leespring.com/product/compression-spring-lc026bc08s-stainless-steel

FM is looking at the possibility of buying a bunch of the FM bolt spring version and providing them on the website at a very reasonable price for folks who have the DT/LS issue with FM bolts.

Do NOT try to use the FM firing pin spring in a different bolt and expect the same results!

The spring needed for most other bolts is DIFFERENT (longer) to get the same resistance. The FM bolt's firing pin spring channel is shorter. The shorter spring doesn't provide the same resistance when used in a bolt with a longer spring channel.

For most other bolts with the longer spring channel (Outerwild, KVP, PSA, Angstadt, Faxon, IDL, etc.) the following longer spring is necessary to provide double the resistance:

LC 026BC 09S: https://www.leespring.com/product/compression-spring-lc026bc09s-stainless-steel

ETA: As someone mentioned in another thread, the original mfgr spring in the Outerwild/PSA/etc. is 0.8" like the FM original spring, however, the firing pin spring channel is longer internally. These bolts more closely follow the original Colt firing pin channel spec, which used a 1" spring. If the FM Lee Spring is used it "may" work, but produces significantly less spring pressure to counter the firing pin bounce. It's too short.

I chose the 1" spring to give double the strength while still working properly, not overcompressing, and closely matching the ID and OD requirements of the firing pin channel.

So, yes, I did really think this through and considered a lot of variables to come up with the specific spring choices I made for the different bolts.

Pre-Production sample of the Mike9-ISU flow-through suppressed upper. Comes as a complete upper and transfers like a suppressor. My impressions. Very slim, zero gas in the face and recoil was very soft. Not the quietest can due to the limited internal volume, but very enjoyable to shoot. (Always wear hearing protection, even with suppressors.) I was told the handguard will undergo revision to open up the ID a little before release to allow easy mlok attachment while OD will remain the same.

Youtube Link: https://youtu.be/yJ3S7MRvQkA

Thanks u/Bracketracer01 for pointing this out!

PSA has the R&D Precision .45 PCC bolt on clearance for $30

I do NOT know the quality of this bolt or its track record, nor am I endorsing it in any way.

https://palmettostatearmory.com/psa-ar45-bolt-carrier-group-7789153.html

I do not get any kickbacks and am not affiliated. I do not sell anything.

Previous post on this topic, FWIW... https://www.reddit.com/r/AR9/comments/1o5jyra/rd\_precision\_45\_bolt\_50\_clearance/

Dropped this morning. Explanation of the "Firing Pin Bounce" dead trigger/light strike problem in 9mm AR blowbacks. Certain Lee Springs seem to work just fine as firing pin springs, providing 2x power. Cost is ridiculous, but this is the best option I've found that's easily and consistently available. I don't know if this will fix the DT/LS consistently until I have a LOT more testing and ammo through the platform.

For FM bolts: LC 026BC 08S

For all others: LC 026BC 09S

Individually the springs are $9 and orders under $40 get whacked with a $20 handling charge and shipping, so it's best to buy several at a time.