JP Rifles AR-15 FMOS Bolt Carrier Not Compatible with Geissle National Match Triggers

[Fire4EffectCA]

What would be the best option for a Mil-Spec AR-15 bolt carrier for use with a JP Rifles enhanced bolt? I have found that the JP Rifles full mass bolt carrier I received with the JP Rifles enhanced bolt is not compatible with the Geissele National Match trigger. The hook under the face of the Geissele National Match hammer is hanging up on the tail of the JP Rifles full mass bolt carrier. A Daniel Defense bolt carrier will work Geissele National Match trigger, but they don’t sell the bolt carrier separately.

 

[TonyTheTiger]

Were I in your position and already had all these parts I'd try to measure the hammer hook interference and decide if I could live with removing a little bit of the hook.

 

[Fire4EffectCA]

Were I in your position and already had all these parts I'd try to measure the hammer hook interference and decide if I could live with removing a little bit of the hook.

Actually what I need is ether the longer hammer face of the SSA-E hammer or material added to the back of the JP Rifles bolt carrier so it replicates the Daniel Defense bolt carrier.

I have discussed this at length with both JP Rifles and Geissele staff. Based on my observations they concluded the combination was not compatible.

 

[TonyTheTiger]

Ah, I misunderstood where the interference was happening.

 

[msgriff]

Actually what I need is ether the longer hammer face of the SSA-E hammer or material added to the back of the JP Rifles bolt carrier so it replicates the Daniel Defense bolt carrier.

I have discussed this at length with both JP Rifles and Geissele staff. Based on my observations they concluded the combination was not compatible.

Great post, explanation and visuals.

I wonder if the JP carrier is the sole outlier, or if this is something that might be hit or miss with other carriers. The dimension of the body of the carrier, measured from the front, that seems relevant looks like 2.81" on a M16 carrier drawing.

 

[Fire4EffectCA]

Great post, explanation and visuals.

I wonder if the JP carrier is the sole outlier, or if this is something that might be hit or miss with other carriers. The dimension of the body of the carrier, measured from the front, that seems relevant looks like 2.81" on a M16 carrier drawing.

I know the Daniel Defense bolt carrier works, but it is Mil-Spec.

 

[Stone111]

I use LWRC's one piece bolt carriers with JP's AR15 bolts, I miced it for you and at that spot its .082" I also run a Cryptic coatings BCG in another rifle and its the same as the LWRC. Both of those are milspec BCG's and I suspect the DD BCG maybe an outlier and an anomily. Personally I would dump that trigger and move on...

https://www.lwrci.com/LWRCI-Direct-Impingement-Bolt-Carrier-Carrier-Only_p_223.html

If you can, check the dimensions at that spot on both the DD and JP BCG and post it up, I am curious.

 

[Fire4EffectCA]

I use LWRC's one piece bolt carriers with JP's AR15 bolts, I miced it for you and at that spot its .082" I also run a Cryptic coatings BCG in another rifle and its the same as the LWRC. Both of those are milspec BCG's and I suspect the DD BCG maybe an outlier and an anomily. Personally I would dump that trigger and move on...

https://www.lwrci.com/LWRCI-Direct-Impingement-Bolt-Carrier-Carrier-Only_p_223.html

If you can, check the dimensions at that spot on both the DD and JP BCG and post it up, I am curious.

I just remembered I have an early 1990’s vintage Colt Competition HBAR that I installed a Geissle National Match Trigger in around 2010. I have not shot it in over a decade. It cycles fine. The profile on the back of this Colt bolt carrier where the hammer rides is identical to the Daniel Defense bolt carrier. According to Geissle their National Match trigger was designed for service rifle competition with a Mil-Spec bolt carrier.

 

[Fire4EffectCA]

I use LWRC's one piece bolt carriers with JP's AR15 bolts, I miced it for you and at that spot its .082" I also run a Cryptic coatings BCG in another rifle and its the same as the LWRC. Both of those are milspec BCG's and I suspect the DD BCG maybe an outlier and an anomily. Personally I would dump that trigger and move on...

https://www.lwrci.com/LWRCI-Direct-Impingement-Bolt-Carrier-Carrier-Only_p_223.html

If you can, check the dimensions at that spot on both the DD and JP BCG and post it up, I am curious.

So far my Colt, LMT and Daniel Defense bolt carriers operate fine with the Geissle National Match Trigger. LMT had a sale this past weekend so I ordered a Mil-Spec bolt carrier from them. Looking forward to getting back to the range. I installed the new National Match Trigger I received from Geissle in my Daniel Defense lower and set the weight to 2-3/4 pounds total.

 

[Krebaum]

I have a JP full mass bolt carrier with GI bolt and Geissele high speed national match trigger and probably 9000 rounds through it with three barrels and three GI bolt with no issues.

 

[Fire4EffectCA]

I sent my bolt carrier back to JP Rifles and they could not see any difference between the bolt carrier I sent back and their latest production. They did replace mine with a new one. There was a definite difference between the back of my Daniel Defense, Colt and LMT bolt carriers compared to the JP Rifles bolt carrier. You can see it in the photos I posted.

 

[Krebaum]

I think your bolt may look different from mine.

 

[Fire4EffectCA]

I think your bolt may look different from mine.

Thanks so much for your post. I looked at the replacement bolt carrier from JP Rifles and it looks like yours. I installed it in the rifle with the replacement Geissle National Match Trigger and it cycles. I am seeing metal wear in the notch below the hammer face with the replacement hammer from Geissle and the replacement bolt carrier from JP Rifles. The JP Rifles mating surface looks fine. What does your hammer face and the notch below look like?

 

[Krebaum]

Your welcome. The hammer looks fine I really do not see any excessive wear on either part.

 

[Krebaum]

From the picture of your bolt. I would round your bolt where it makes contact with the hammer and polish it so it looks more like the newer bolts and I think your problem would go away.

 

[Fire4EffectCA]

Your welcome. The hammer looks fine I really do not see any excessive wear on either part.

Here are photos of my Geissele National Match Hammer and the replacement hammer from Geissele.

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[Fire4EffectCA]

From the picture of your bolt. I would round your bolt where it makes contact with the hammer and polish it so it looks more like the newer bolts and I think your problem would go away.

No need to round the replacement bolt carrier from JP Rifles. It looks like yours.

 

[Krebaum]

Pic of my hammer with over 9000 rnds with the JP full mass carrier. I do not see any excessive wear.

 

[Fire4EffectCA]

It appears the replacement hammer will work with the new replacement bolt carrier from JP Rifles. Hard to say which part was the source of the problem. Both original parts showed interference evidence. The new JP Bolt carrier does not show any unusual marks.