Daily Bulletin » Barrel Fitting

Botched Gunsmithing — How NOT to Headspace a Barrel

Editor — Wed, 12 Aug 2026 08:07:48 +0000

This barrel’s shoulder was 0.025″ off the action because Red Locktite had been used on the threads.

Gunsmith Thomas ‘Speedy’ Gonzales offered this interesting report about how NOT to headspace a barrel. Hopefully you never discover something like this…

“A good friend and customer sent this rig in for repair after FedEx damaged the rifle during inbound transport from another smith. After repairing the stock and rebedding it, I decided to re-polish the barrel to make the repair perfect. Well this just added insult to injury as the barrel did not want to come off. After a few choice words, the barrel finally broke free only to reveal something very disturbing. It seems the barrel had been ‘headspaced’ by using RED Loctite to hold it in place.” [Editor: That’s definitely NOT how barrels should be fitted.]

Speedy was not happy: “I hope the smith that did this sees the photos and realized what jeopardy he put my customer in or anyone who shot the rifle for that matter. When cleaned up, the shoulder on the barrel was over 0.0250″ (25 thousandths) away from the face of the receiver.” [Editor: That’s a lot in this business]. Check out the images below to see how much the barrel rotated further inward when cleaned up. The barrel spun in nearly another eighth-turn or more. Not good.

Erratic POI? Check Scope, But It Might Be a Loose Barrel Issue

Editor — Sun, 18 Jan 2026 06:30:44 +0000

Are you seeing unpredictable changes in Point of Impact on your target? Think you may have a scope issue? Well maybe not — when was the last time you checked your BARREL?

Yes scopes do fail, and scope bases/rings do get loose. But sometimes problems with erratic POI shifts are caused by a LOOSE BARREL. This issue came up a while back in our Shooter’s Forum. One member complained that his zero was shifting from day to day — by as much as two inches at 100 yards. He was convinced he had a scope problem, based on erratic POI:

“I think my scope loses 1 to 3 MOA per day. When I shot my rifle Monday it was dead on. On Tuesday it was 1″ low. Then on Wednesday it was 1 or 2″ lower. I don’t get it. — the elevation knob never touched. Scope will track and return to zero that day perfect. Yes EVERYTHING has been checked, nothing loose. What is the chance the erector tube spring has gone south? For the record this is a Vortex GE. Never had a bad scope, but this has me wondering”. — LB

On Forum member told LB to send the scope right back to the manufacturer. Two other members suggested mounting the scope on a different rifle to test. Good advice. That’s generally a smart strategy before you conclude a scope has gone bad…

Could Problem Be the Scope Base?
Two Forum members, ExPiper and Dickn52, suggested checking the scope base, recounting their past experiences with troublesome bases. This was intelligent — anyone with a POI problem should check all the optics attachments:

“Went crazy one day chasing my impacts on a 100-yard target. Shots would group fine for three then go nuts for 4-5. I cranked and un-cranked for about an hour. Then I reached up and the base wobbled on the rifle. Removed scope, tightened base screws and back in business.” — Dickn52

“Years ago I had a problem [where] shots were climbing with almost every shot. I was blaming the scope. However, when removing the scope I noticed that the 20 MOA base was cracked and getting wider with every shot. Needless to say I replaced the base and the problem was solved. — ExPiper

Eureka Moment — The problem was the BARREL, not the Scope

There were many helpful suggestions, but member PirateAmmo steered LB to the real problem — a loose BARREL: “We had a problem on a home-built AR-platform rifle once, barrel was loose a tad…”

Member Snert chimed in: “Yep — I had a PPC that suddenly went 19″ low. Picked up gun off bench by barrel and felt a wiggle. I tightened the barrel and the POI went 19 inches up”.

Problem Solved — Barrel Tightened up and POI Back to Normal
The gentleman with the POI problem took the advice of PirateAmmo and checked his barrel. BINGO! Low and behold, the barrel WAS loose.

LB posted: “Barrel loose by about 2%, checked it twice before and didn’t find it the first two times”.

After LB re-tightened his barrel, his rifle started shooting normally again. No more shooting low by 1-2 inches. Problem solved. The fix didn’t cost a penny and now LB doesn’t have to send a perfectly good optic back to the manufacturer.

Lesson learned? Check ALL the variables before you assume a scope has gone bad. Along with the barrel, also check your action screw tension, and of course the scope base and rings.

“Blueprinting” Action & Barrel Fitting — Explained by Jim Borden

Editor — Fri, 14 Nov 2025 13:30:07 +0000

Jim Borden, the very knowledgeable owner of Borden Accuracy, provided an interesting historical insight about barrel fitting and the term “blueprinting”. Jim has posted on his Borden Accuracy Facebook page an explanation of the term “blueprinting” as it originally was used with respect to barrel/shoulder/lug fitting.

Barrel/Shoulder Fit and Blue-Printing
Jim told us: “Something often overlooked on barrel installation is the shoulder fit. Many are so overly obsessed with doing a crank-on fit of threads that the shoulder contact is overlooked. Full, solid barrel shoulder to recoil lug or action face is critical to optimum accuracy and precision.

Many years ago part of the ‘blueprinting’ of an action was the use of Prussian blue to ‘blueprint’ lug fit, thread fit, and barrel shoulder fit. It was a colloquial expression that had nothing to do referring to a blueprint or drawing of the action.” Bet you didn’t know that!

About the photo below, Jim noted: “the fuzzy look on the threads is a liberal coating of Never-Seez thread lubricant.”

Look carefully to see the Prussian Blue applied to the barrel shoulder, plus Never Seez on threads.

How NOT to Headspace a Barrel — Gunsmithing Gone Bad

Editor — Thu, 16 Jan 2025 11:18:57 +0000

This barrel’s shoulder was 0.025″ off the action because Red Locktite had been used on the threads.

Gunsmith Thomas ‘Speedy’ Gonzales offered this interesting report about how NOT to headspace a barrel. Hopefully you never discover something like this…

The “Blueprinting” Process for Barrel Shoulder/Lug Fitting

Editor — Sun, 15 Dec 2024 06:06:08 +0000

About the photo below, Jim noted: “the fuzzy look on the threads is a liberal coating of Never-Seez thread lubricant.”

Look carefully to see the Prussian Blue applied to the barrel shoulder, plus Never Seez on threads.

Erratic POI Might Be Loose Barrel Issue, Not Scope Problem

Editor — Fri, 19 Jan 2024 13:10:01 +0000

Are you seeing unpredictable changes in Point of Impact on your target? Think you may have a scope issue? Well maybe not — when was the last time you checked your BARREL?

“I think my scope loses 1 to 3 MOA per day. When I shot my rifle Monday it was dead on. On Tuesday it was 1″ low. Then on Wednesday it was 1 or 2″ lower. I don’t get it. — the elevation knob never touched. Scope will track and return to zero that day perfect. Yes EVERYTHING has been checked, nothing loose. What is the chance the erector tube spring has gone south? For the record this is a Vortex GE. Never had a bad scope, but this has me wondering”. — LB

Eureka Moment — The problem was the BARREL, not the Scope

Member Snert chimed in: “Yep — I had a PPC that suddenly went 19″ low. Picked up gun off bench by barrel and felt a wiggle. I tightened the barrel and the POI went 19 inches up”.

Problem Solved — Barrel Tightened up and POI Back to Normal
The gentleman with the POI problem took the advice of PirateAmmo and checked his barrel. BINGO! Low and behold, the barrel WAS loose.

LB posted: “Barrel loose by about 2%, checked it twice before and didn’t find it the first two times”.

Lesson learned? Check ALL the variables before you assume a scope has gone bad. Along with the barrel, also check your action screw tension, and of course the scope base and rings.

Erratic POI? Check Your Scope — But It Could Be a Loose Barrel

Editor — Wed, 02 Mar 2022 11:00:21 +0000

Are you seeing unpredictable changes in Point of Impact on your target? Think you may have a scope issue? Well maybe not — when was the last time you checked your BARREL?

Yes scopes do fail, and scope bases/rings do get loose. But sometimes problems with erratic POI shifts are caused by a LOOSE BARREL. This issue came up recently in our Shooter’s Forum. One member complained that his zero was shifting from day to day — by as much as two inches at 100 yards. He was convinced he had a scope problem, based on erratic POI:

“I think my scope loses 1 to 3 MOA per day. When I shot my rifle Monday it was dead on. On Tuesday it was 1″ low. Then on Wednesday it was 1 or 2″ lower. I don’t get it. — the elevation knob never touched. Scope will track and return to zero that day perfect. Yes EVERYTHING has been checked, nothing loose. What is the chance the erector tube spring has gone south? For the record this is a Vortex GE. Never had a bad scope, but this has me wondering”. — LB

Eureka Moment — The problem was the BARREL, not the Scope

Member Snert chimed in: “Yep — I had a PPC that suddenly went 19″ low. Picked up gun off bench by barrel and felt a wiggle. I tightened the barrel and the POI went 19 inches up”.

Problem Solved — Barrel Tightened up and POI Back to Normal
The gentleman with the POI problem took the advice of PirateAmmo and checked his barrel. BINGO! Low and behold, the barrel WAS loose.

LB posted: “Barrel loose by about 2%, checked it twice before and didn’t find it the first two times”.

Lesson learned? Check ALL the variables before you assume a scope has gone bad. Along with the barrel, also check your action screw tension, and of course the scope base and rings.

Jim Borden Explains “Blueprinting” for Barrel Shoulders & Lugs

Editor — Sat, 16 Jan 2021 12:56:19 +0000

Jim Borden, the very knowledgeable owner of Borden Accuracy, provided an interesting historical insight about barrel fitting and the term “blueprinting”. Jim recently posted on the Borden Accuracy Facebook page an explanation of the term “blueprinting” as it originally was used with respect to barrel/shoulder/lug fitting.

About the photo below, Jim noted: “the fuzzy look on the threads is a liberal coating of Never-Seez thread lubricant.”

Look carefully to see the Prussian Blue applied to the barrel shoulder, plus Never Seez on threads.

Gunsmithing Gone Bad — How NOT to Headspace a Barrel

Editor — Fri, 21 Feb 2020 19:08:15 +0000

This barrel’s shoulder was 0.025″ off the action because Red Locktite had been used on the threads.

Gunsmith Thomas ‘Speedy’ Gonzales offered this interesting report about how NOT to headspace a barrel. Hopefully you never discover something like this…

TECH TIP — Check Barrel Tightness If POI Shifts Erratically

Editor — Wed, 22 Jan 2020 07:05:54 +0000

Are you seeing unpredictable changes in Point of Impact on your target? Think you may have a scope issue? Well maybe not — when was the last time you checked your BARREL?

“I think my scope loses 1 to 3 MOA per day. When I shot my rifle Monday it was dead on. On Tuesday it was 1″ low. Then on Wednesday it was 1 or 2″ lower. I don’t get it. — the elevation knob never touched. Scope will track and return to zero that day perfect. Yes EVERYTHING has been checked, nothing loose. What is the chance the erector tube spring has gone south? For the record this is a Vortex GE. Never had a bad scope, but this has me wondering”. — LB

Eureka Moment — The problem was the BARREL, not the Scope

Member Snert chimed in: “Yep — I had a PPC that suddenly went 19″ low. Picked up gun off bench by barrel and felt a wiggle. I tightened the barrel and the POI went 19 inches up”.

Problem Solved — Barrel Tightened up and POI Back to Normal
The gentleman with the POI problem took the advice of PirateAmmo and checked his barrel. BINGO! Low and behold, the barrel WAS loose.

LB posted: “Barrel loose by about 2%, checked it twice before and didn’t find it the first two times”.

Lesson learned? Check ALL the variables before you assume a scope has gone bad. Along with the barrel, also check your action screw tension, and of course the scope base and rings.