Gunsmithing Heavy bolt lift on Rem 700 after barrel change

[JackShiloh]

I'm putting together a 308 bolt rifle with a variety of spare parts. The barrel is a 20" truck axle that the original owner said has around 2K rounds (barrel was chambered and headspaced for a different receiver) . I put it on a new Rem 700 receiver with a 0.190" thick Remington factory recoil lug I had laying around. Bolt closes on the GO gauge and doesn't close on the NO-GO gauge. Took it to the range and it shot pretty well with FGGM factory ammo. However, the bolt was very difficult to open after firing. Thinking it needed some additional headspace I bought a PTG 0.200" recoil lug. With that installed, bolt closes on both gauges (did not fire for obvious reasons)

Before I go tracking down a 0.195" recoil lug I'd like to hear from someone else that I'm headed the right direction. I'm not an amateur, but I'm no expert either. Any advice is appreciated.

 

[Mordamer]

There is only .003" to .004" of difference between go and no go. You need to go back to the .190" recoil lug and look for the real problem causing hard extraction. Head space is not rocket science. If it passes a go and no go gauge then stop messing with head space.

Are the rounds over pressure? Show us a close up picture of the case heads on the fired brass that was hard to extract.

 

[ShtrRdy]

Go back to the 0.190" lug and look for other causes. Take a good look at the throat and bore to see if there is an excessive amount of fouling which could be causing a restriction.

 

[JackShiloh]

Mordamer and ShtrRdy,

Thanks for the replies. The ammo fired was factory Federal Gold Medal Match 168g and none of the cases showed any signs of over pressure (no extractor marks, etc.)

Since the history of the barrel is somewhat unknown, I think a thorough inspection/cleaning is in order.

Jason

 

[OG10]

if you hadn't said that it was a new Remington 700 action I would not mention this however check to make sure that you're getting primary extraction when you open your bolt a lot of the new Remington 700 actions I have seen the bolt is not very well-timed and therefore they don't extract, as if it was an over-pressured load just a thought.

 

[JackShiloh]

OG10,

Thanks for the tip. Any advice for how to check this?

 

[spife7980]

OG10,

Thanks for the tip. Any advice for how to check this?

 

[flatland1]

There's a difference between a bolt being hard to open and not having the correct primary extraction. If the bolt lift is excessive, but then it's easy to extract the fired case, it's not the primary extraction. If the bolt lift is relatively easy, but you have difficulty in extracting the fired case, that could very well be due to lack of primary extraction. The whole idea of "primary" extraction is the correct positioning of the bolt handle on the bolt body so that the root of the bolt handle will engage the bevel at the top of the bolt handle slot in the rear receiver ring, so that there's a mechanical (primary) bit of extraction happening as the bolt handle engages that bevel in the action. That's supposed to break the fired case loose from the chamber walls, thus making it easy to retract the bolt to extract & eject the fired case.

ETA - Confession - the first PTG bolt body that I used in a M700 LA was purchased before PTG started making one-piece bolts, and I had to silver solder the bolt handle onto the body. I think I had it indexed correctly for timing & primary extraction, but the "jig" I'd made to hold the handle in place while soldering was pretty poor, and the handle moved a tad bit when the silver solder got hot enough to flow. I tried shooting a 3x1000 prone match out at Byers, Co. with that rifle in 284 Win, and had no end of issues with extraction, due to lack of primary extraction. The rifle shot well - I shot a 200-8x in the 2nd match of the day, but it was a struggle. I had to break position every other shot or so in order to yank the bolt to the rear to extract fired cases. I took the bolt back out to the shop after I got it home, heated it up to melt the solder, then cleaned it all up & re-soldered it. Viola! - problem fixed. Screw it - after that fiasco, I bought only single piece bolts from PTG, and never had an extraction problem again.

 

[JackShiloh]

@spife7980 thanks for the video link. I'll check that tonight.
@flatland1 thanks for confirmation that the bolt timing can cause the issues I'm experiencing

 

[Mordamer]

@spife7980 thanks for the video link. I'll check that tonight.
@flatland1 thanks for confirmation that the bolt timing can cause the issues I'm experiencing

Is the bolt lift heavy or is the extraction hard after the bolt is raised all the way to the top?

 

[JackShiloh]

It's been a few weeks so I'll check tonight. I'll also do the primary extraction test shown in the posted video.

 

[JackShiloh]

Had a chance to check the primary extraction per the video provided on both the "problem" receiver and a different Rem700 receiver I have. Removed both firing pins as instructed. Neither indicated an issue based on the content presented in the video. However, the problem receiver's bolt is noticeably tight upon open and closing. In the video you can see the bolt turning freely because the firing pin is removed and cocking action is occurring. The other Rem700 bolt behaved just like the video.

I then took the problem receiver out back and fired three rounds. This time I didn't notice the difficulty opening the bolt and extracting the spent case like I did on my first range trip (the reason this thread was started). However, the bolt open and close are noticeably tight....both when closing on an empty chamber and on a loaded factory round. So the issue I'm trying to address is: "What might cause the bolt open/close to be tight under all scenarios (firing pin removed and no cartridge, firing pin in and closing on empty chamber, and firing pin in closing on loaded factory round?"

Any ideas are appreciated

 

[flatland1]

Are you using a custom bolt, or the original bolt with s/n matching that of the receiver?

 

[JackShiloh]

Original factory bolt with matching serial

 

[Mordamer]

Barrel counterbore might be either too shallow or the diameter is too small. Color the front face of the bolt nose and the outer diameter of the bolt nose with dykem or a sharpie and see if it rubs off anywhere when the bolt is cycled. If so, the counterbore needs to be opened up or cut deeper. This could happen if your rem 700 has a longer bolt nose than the one the barrel was cut for.

 

[JackShiloh]

Mordamer wins the prize. Colored the face and outer diameter with a sharpie. Bolt face showed nothing but outer diameter has a clear rub mark at about the 2pm position with the bolt closed. I'll take it to my local gunsmith to correct the issue.

Thanks to all that assisted. I'm going to change the title of the thread in case anyone else encounters something similar.