New production bolt/upper (ROF)

[GK8041]

Any first hand experience with currently available CNC bolts installed in OEM M10/9 uppers or new OEM spec uppers like the side charging variants sold by premium MAC parts vendors - but not including the larger spec Lage Mfg uppers? Did I read correctly the modern machined bolts are slightly heavier than the original cast ones?

I'm curious if these new bolts or combination of new bolt and side charging uppers noticeably affect ROF?

 

[thumpy]

I have had the one from Ftf industry’s top charging handle for a few years now. Absolute love it. Increased the reliability on my m10/9. I didn’t have many problems before an occasional stoppage like any mg can have… but since I swapped the bolt I’ve done 20-30k rnds on it with Zero malfunctions. Great little upgrade in my opinion. There is a slight change in rof it’s slightly slower… but to most people I don’t think they’d even notice it. When you shoot it’s still 1000rpm gun !

 

[root]

Have not noticed a cycle rate difference between my three OEM standard uppers or the side charger I have.
M10 45aarp gun.

I want slow I use a lage upper if I want super fast I stick the 22 upper on it.
I can pull singles on all my lage uppers
Doubles on my OEM sized uppers
Strings of 5 on the 22 flemming upper.

 

[Jmacken37]

I'd replace all the internals possible with Lage parts.
The OEM stuff is good to keep for collector value, but functionally, the CNC'd modern parts are a huge improvment.

 

[PDXsparky]

I'd replace all the internals possible with Lage parts.
The OEM stuff is good to keep for collector value, but functionally, the CNC'd modern parts are a huge improvment.

This ^ for me.

 

[BlackBelt]

Although I have the newer style cnc bolts in 45 and 9mm I still just mainly use the old style bolts simply because they run flawlessly as well. I have never had any problems with either style.

 

[strobro32]

I just saw the CNC bolt in my parts bin the other day. I now remember that I replaced the newer CNC bolt on my M11A1 because it was less reliable than the cast stock bolt. Now that I think about it, the CNC bolt was changed because it was not as reliable on the large grip/mags SWD M11/380. The smaller grip/mags on the RPB are more reliable to begin with so I might test the ROF between the CNC and cast bolts if I get the chance.

 

[Kursk]

The original bolts are more reliable than the newer FtF CNC bolts in my M/10 SMG

 

[boomer535]

The FTF M10/45 bolt runs perfect in my M10/45’s. Just as good as my original cast bolts except the new bolt kicks the brass out farther. Here is the new bolt in action.

 

[MitchWerbellsGhost87]

For the purpose of shooting, the new CNC machined bolts are the way to go. If you want an original collectible gun, then the old cast bolt is the only option.

I believe the new machined bolts sold by FTF, and possibly practical solutions as well, are manufactured by a fella named Russell Weeks out of Avondale estates, GA. He ran a company called “RPB” or ”Russel’s parts bin”. Hes been in the game since the early 80s. I believe he makes the new bolts as well as the modified version of it for LAGE mfg.

in my experience the new CNC machined bolts run a bit better. from the perspective of a shooter vs a collector, the new bolt would be the best bet for reliability in my opinion. It is also impossible to find replacement extractors for the old cast design or the 80s SWD machined design, as it used the same extractor as the cast bolt. replacement extractors for the new design are readily available through any of the distributors that sell the bolt itself.

i have had a handful of the old SWD machined “slab side” bolts from the 80s and they seem to run nicely also, though they are a bit tight in the upper sometimes and occasionally the upper has to be “stretched” out a tad for it to run smoothly. i don’t think this is an issue with the newer units but I don’t have enough experience with them to comment on that.

i personally noticed a pretty drastic reduction in ROF with the M10/9 single feed SWD machined bolt vs the original MAC/RPB cast double feed 9mm bolt. The SWD single feed machined M10/9 bolt with 147gr FMJ and a can was running at damn near UZI rates of fire.

there are a lot of factors that could play into this and it is likely not the result of the machined bolt being heavier alone. If anything it was a combination of the different recoil spring tensions with the weight of the bolts as well, maybe even the single feed system vs double feed, with the single feed system causing a bit of drag on the bolt with the zytel magazine‘s feedlips.

 

[SecondAmend]

....

i personally noticed a pretty drastic reduction in ROF with the M10/9 single feed SWD machined bolt vs the original MAC/RPB cast double feed 9mm bolt. The SWD single feed machined M10/9 bolt with 147gr FMJ and a can was running at damn near UZI rates of fire.

there are a lot of factors that could play into this and it is likely not the result of the machined bolt being heavier alone. If anything it was a combination of the different recoil spring tensions with the weight of the bolts as well, maybe even the single feed system vs double feed, with the single feed system causing a bit of drag on the bolt with the zytel magazine‘s feedlips.

While not directly comparable, with an M16 shooting 9mm in a closed bolt, direct blowback (i.e., not delayed) system, I've measured identical ROFs when comparing single feed Glock mags (using the respective magwell adapter) and dual feed Uzi mags (with their appropriate magwell adapter).
MHO, YMMV, etc.

 

[MitchWerbellsGhost87]

While not directly comparable, with an M16 shooting 9mm in a closed bolt, direct blowback (i.e., not delayed) system, I've measured identical ROFs when comparing single feed Glock mags (using the respective magwell adapter) and dual feed Uzi mags (with their appropriate magwell adapter).
MHO, YMMV, etc.

I’m sure there really shouldn’t be any drastic difference in ROF due to single vs double feed, but I think in the case of this particular gun there may have been a little bit of bolt drag because of the ill fitting zytel magazines and their propensity to rub against the bolt. I think the single feed glock mags are a bit more reliable and less likely to drag the way that the MAC bolt does with the single feed zytel magazine.

 

[brenbuilds]

For the purpose of shooting, the new CNC machined bolts are the way to go. If you want an original collectible gun, then the old cast bolt is the only option.

I believe the new machined bolts sold by FTF, and possibly practical solutions as well, are manufactured by a fella named Russell Weeks out of Avondale estates, GA. He ran a company called “RPB” or ”Russel’s parts bin”. Hes been in the game since the early 80s. I believe he makes the new bolts as well as the modified version of it for LAGE mfg.

in my experience the new CNC machined bolts run a bit better. from the perspective of a shooter vs a collector, the new bolt would be the best bet for reliability in my opinion. It is also impossible to find replacement extractors for the old cast design or the 80s SWD machined design, as it used the same extractor as the cast bolt. replacement extractors for the new design are readily available through any of the distributors that sell the bolt itself.

i have had a handful of the old SWD machined “slab side” bolts from the 80s and they seem to run nicely also, though they are a bit tight in the upper sometimes and occasionally the upper has to be “stretched” out a tad for it to run smoothly. i don’t think this is an issue with the newer units but I don’t have enough experience with them to comment on that.

i personally noticed a pretty drastic reduction in ROF with the M10/9 single feed SWD machined bolt vs the original MAC/RPB cast double feed 9mm bolt. The SWD single feed machined M10/9 bolt with 147gr FMJ and a can was running at damn near UZI rates of fire.

there are a lot of factors that could play into this and it is likely not the result of the machined bolt being heavier alone. If anything it was a combination of the different recoil spring tensions with the weight of the bolts as well, maybe even the single feed system vs double feed, with the single feed system causing a bit of drag on the bolt with the zytel magazine‘s feedlips.

Supposedly, the guy that runs USmachineguns.com might make the bolts for FTF Solutions. I spoke with him on the phone once and he said much of their parts are made in house. That being said, I can't say for certain. FTF and USmachineguns do appear to have the same CNC machine bolts though.

I agree cast bolts are largely of collector interest; the original 1911/UZI style extractors are expensive and less reliable. Additionally, many have been bent by people swapping uppers that have barrels that lack an extractor cut out.

The cyclic rate is certainly lower with machined bolts due to the tighter grain structure and weight in comparison to cast bolts ( which typically have lightening cuts anyways). I also don't miss the cast bolt cocking knobs, especially in Fat MAC's that have the early, very top heavy knob that is prone to breaking ( and hitting you in the head if you're lucky!).

 

[MitchWerbellsGhost87]

Supposedly, the guy that runs USmachineguns.com might make the bolts for FTF Solutions. I spoke with him on the phone once and he said much of their parts are made in house. That being said, I can't say for certain. FTF and USmachineguns do appear to have the same CNC machine bolts though.

I agree cast bolts are largely of collector interest; the original 1911/UZI style extractors are expensive and less reliable. Additionally, many have been bent by people swapping uppers that have barrels that lack an extractor cut out.

The cyclic rate is certainly lower with machined bolts due to the tighter grain structure and weight in comparison to cast bolts ( which typically have lightening cuts anyways). I also don't miss the cast bolt cocking knobs, especially in Fat MAC's that have the early, very top heavy knob that is prone to breaking ( and hitting you in the head if you're lucky!).

There is a reason those old cast bolts are often referred to as “speed bolts”. many have lightning cuts, but not all. There are also speed bolts that are slab sided on the back without the cuts..

USMG doesn’t make his MAC bolts in house. He gets them from the same source as the other distributors. Im fairly certain it’s Russell Weeks. I believe he runs the new “RPBindustries” website as well, but they rarely have much in the way of inventory, seems like most of his business is wholesale for the big suppliers.

 

[SecondAmend]

I’m sure there really shouldn’t be any drastic difference in ROF due to single vs double feed, but I think in the case of this particular gun there may have been a little bit of bolt drag because of the ill fitting zytel magazines and their propensity to rub against the bolt. I think the single feed glock mags are a bit more reliable and less likely to drag the way that the MAC bolt does with the single feed zytel magazine.

Brings back memories of the AutoWerkes &/or Gun Parts USA MAC DIRR (Drop In Rate Reducer).

 

[MitchWerbellsGhost87]

Brings back memories of the AutoWerkes &/or Gun Parts USA MAC DIRR (Drop In Rate Reducer).

Yes. Same basic idea as the old autowerkes rate reducer. Create a little bit of drag, just enough to slow down the bolt.

 

[pmf]

Brings back memories of the AutoWerkes &/or Gun Parts USA MAC DIRR (Drop In Rate Reducer).

Wonder what ever happened to that guy. He owed me (and many other folks) money. Someone tipped me about sending a letter to the Missouri Attorney General. A few months later, I got a check, I believe from his parents, with an apology. Did he die? End up in jail? Anyone know?

 

[MitchWerbellsGhost87]

Wonder what ever happened to that guy. He owed me (and many other folks) money. Someone tipped me about sending a letter to the Missouri Attorney General. A few months later, I got a check, I believe from his parents, with an apology. Did he die? End up in jail? Anyone know?

I believe autowerkes still operates out of MO.

 

[chili17]

Last I heard Erik (Autowerkes ) works on and off at C&S Metalwerks
Gunparts guy died in a car accident

 

[MitchWerbellsGhost87]

Last I heard Erik (Autowerkes ) works on and off at C&S Metalwerks
Gunparts guy died in a car accident

I was confusing the two. I was thinking of C&S metalwerkes all along, out of MO, but now that you mention it, I think the autowerkes guy sold off a bunch of MAC small parts last year, I ended up with a handful of them. Not 100% positive, but I believe that’s where they came from. So he may be out of the biz?