View Full Version : FTF issues?
Guys I have a BCM 11.5" upper that has shot 1000's of troublefree rounds of any type of ammo I've fed it to include Tula and Wolf. A few weeks ago I had a DD Lite 10.0 rail and DD LoPro gasblock installed and today was my first time getting it out to re-zero. Funtioned fine with various types of ammo except the Tula/Wolf which had several instances where it failed to feed jamming on the feedramp at a 45 degree angle.
Any ideas what may have changed during the rail install to cause these issues?
FWIW, I'm also running an ST-T2 buffer an Tubbs Flatwire Spring. Any help/suggestions would be appreciated as I'm a bit disappointed that an upper that had been 100% since day one is now having issues.
Take a close look at the feed ramps. Is there any kind of visible lip? It should be a continuous plane. Since your barrel would've been removed I'm thinking it may not be seated the same as before.
Does it jam more with HP's or does it jam with FMJ too?
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Is the ST-T2 buffer and Tubbs Flatwire Spring new? or were they on the gun when it was functioning correctly?
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make sure the new gas block is properly aligned. Off by a little and the gas port holes won't line up right and it wil essentially be under gassed
That would be my guess as well. It's the only thing that makes sense.
make sure the new gas block is properly aligned. Off by a little and the gas port holes won't line up right and it wil essentially be under gassed
FWIW, I'm also running an ST-T2 buffer an Tubbs Flatwire Spring
Were these added at the same time as the gas block and rail?
Were these added at the same time as the gas block and rail?
I think your buffer is too heavy for Tula/ Wolf. Put the old buffer in and try it out.
That would be my guess as well. It's the only thing that makes sense.
make sure the new gas block is properly aligned. Off by a little and the gas port holes won't line up right and it wil essentially be under gassed
I vote for gas block alignment. The gun ran fine with that buffer before the gas system was re-built for the rail install. I had to re-build a guys brand new "custom" upper for him 'cause he came in to test his new $2500 "badass custom" rifle and it was a single shot. Properly aligned the gas block and it ran like a scalded dog. If those holes are even just a little mis-aligned, it won't work.
No, he said that the buffer and spring was replaced at the same time as the rail.
The fact that the weapon is working with all ammo except the Tula/ Wolf makes me think that the extra heavy buffer is the issue.
He did not say they were replaced...the OP has not yet clarified that. He only said that is what he is running. We still don't know if he was running them before the problems.
If they are new, then I agree they could be part or all of the problem.
The reason I suggested GB alignment is because I made that mistake when I put my Troy rail on. I had the BG pushed back a bit to far and it would randomly fail to lock the bolt open on the last round shooting wolf. I adjusted the gas block correctly and it functions perfectly now.
Sorry about that I misread the post.
The_Biased_Observer
02-16-11, 18:03
Most barrels have the gas port drilled back a few thousands to accommodate the handguard mounting thing (the name escapes me). When the gas block is installed without the plate it often sits too far towards the lip machined on the barrel exterior resulting in poor.gas flow. Many barrels are pre dimpled but many are not. Set the gas block back a bit and change to a lighter buffer.
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Sorry it took me so long to get back to you guys but I've been busy. To clarify, the ST-T2 Buffer and Tubbs spring were on the gun before adding the Lite Rail. The only changes that were made were the addition of the Lite rail and the require lo pro gas block.
FWIW, I sent the upper to Daniel Defense who did the install at no cost. The gas block is pinned so would that cause an issue with trying to verify and/or correct alignment?
I'm gonna get back out to the range tomorrow and try a standard buffer/spring to see how that works.
I will say that the gun does seem to shoot slightly softer since the adding the Lite rail which makes me wonder if their is an alignment issue.
If DD installed and pinned the block then it should be GTG. I would put a stock carbine spring and H buffer in there and see what happens.
Sorry it took me so long to get back to you guys but I've been busy. To clarify, the ST-T2 Buffer and Tubbs spring were on the gun before adding the Lite Rail. The only changes that were made were the addition of the Lite rail and the require lo pro gas block.
FWIW, I sent the upper to Daniel Defense who did the install at no cost. The gas block is pinned so would that cause an issue with trying to verify and/or correct alignment?
I'm gonna get back out to the range tomorrow and try a standard buffer/spring to see how that works.
I will say that the gun does seem to shoot slightly softer since the adding the Lite rail which makes me wonder if their is an alignment issue.
Headed out to try it again in the morning with a standard buffer/spring since I have those on hand. If it works I'll order a H buffer to try as well.
Most barrels have the gas port drilled back a few thousands to accommodate the handguard mounting thing (the name escapes me). When the gas block is installed without the plate it often sits too far towards the lip machined on the barrel exterior resulting in poor.gas flow. Many barrels are pre dimpled but many are not. Set the gas block back a bit and change to a lighter buffer.
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I usually keep an extra front plate exactly for this reason. Install everything with the plate installed, disassemble and then put it all back together without the plate. Don't bother doing this if the barrel comes pre-dimpled.
*update*
Took it back out today and ran some steel through expecting the same issues. I was pleased to find it back to running 100% with all types of ammo. Not sure what the issue was but it seems to have correcte itself. Thanks for all the suggestions.
Well, if you took out the spring and buffer and put the standard ones back in then I think you found the issue.
Tula is crap. I can’t say the same about Wolf because I have never tried it..
No switches were made...stayed with my set up of ST-T2 buffer and Tubbs spring. Was glad to see it back to running like a top with even cheap ammo.
I don't know how confident I would be if I couldn't track the issue down. I would still try and different spring and buffer.
No switches were made...stayed with my set up of ST-T2 buffer and Tubbs spring. Was glad to see it back to running like a top with even cheap ammo.
Possibly a bit of debris or a burr inside the gas block or tube. Sounds like it's all blown out now. Run it some more to verify
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