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Discussion Starter · #1 ·
I happen to get a good deal on what seems to be a NOS Winnie bolt, so let me know if this is ok:

I bought a BRAND NEW SIA Scout. Have been upgrading parts to USGI it (bought a CMP Grade A kit), and want to swap the existing SAI bolt with this Winnie bolt. I don't have headspace gauges.

Anyway, I stripped both bolts and tested both with resized, in spec cases. Both bolts close fine into full battery (both bolts are COMPLETELY stripped, ejector, extractor and firing pin removed)

I then took some other various commercial ammo I had. The SAI bolt actually needs a little lug coaxing with my thumb to go into full battery on commercial Winchester 308 ammo. apply a bit of pressure on the right bolt lug put it into battery. The same exact situation exists with the Winnie bolt. I am applying no more pressure than a bolt slamming forward.

Would you say that I am good to go with this bolt? Once again this is a brand new gun/barrel, so my major concern was "GO", not "NO GO"
 

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I use Clymer.

Do not trust Forster gages, they are soft and conflict themselves. Also, HS gages have to be certified at regular intervals. This is not cheap, and is inconvenient. I'll get flamed for this, but "gunsmith's" have been making a fortune off of this, while fanning the flames of 'danger' on this topic since the '30s. Improper headspace will do one of three things. Insufficient, will not chamber (could lead to slamfire in substandard M14 type rifles, not a concern with quality receivers). Excessive 1. round will not fire, because firing pin will not contact primer, or 2. round fires, front half of case seals, back one third is forced back under 50,000 copper units of pressure, and either stretches beyond usability, or separates. This does not apply to the Mauser Controlled Feed, in which the extractor holds the case head against the bolt face. HTH,dave
 

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Also, toki,

You're way smarter than the 'gunsmith' in (unnamed state) who 'checked' a customer's M1A by inseting the gage in the chamber and letting the fully assembled bolt slam shut on it. He then declared the rifle 'unsafe' and offered to 'fix' it for several hundred dollars ("I won't know how much until I get in there and see what the problem is.") Normally when in someone else's shop, I am a mouse at a cat show, but this time I quietly convinced the 'customer' to leave, then we went to a range where I fired his rifle successfully with several different brands of ammo. Caveat Emptor.
 

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Discussion Starter · #6 ·
Do not trust Forster gages, they are soft and conflict themselves. Also, HS gages have to be certified at regular intervals. This is not cheap, and is inconvenient. I'll get flamed for this, but "gunsmith's" have been making a fortune off of this, while fanning the flames of 'danger' on this topic since the '30s. Improper headspace will do one of three things. Insufficient, will not chamber (could lead to slamfire in substandard M14 type rifles, not a concern with quality receivers). Excessive 1. round will not fire, because firing pin will not contact primer, or 2. round fires, front half of case seals, back one third is forced back under 50,000 copper units of pressure, and either stretches beyond usability, or separates. This does not apply to the Mauser Controlled Feed, in which the extractor holds the case head against the bolt face. HTH,dave
Yeah, I would be concerned if it was an older, worn receiver and/or barrel. Or even a bolt where the lugs were worn. Bolt looks brand new.
We are talking about a new rifle where I used resized, in spec (I checked with my case headspace gauge. I do have one of those. ;) ) All my cases allow the bolt to go into full battery, outside of the few that needed coaxing (although the original bolt needed the same coaxing). I also chambered empty cases that were primed, and let the bolt slam home. I did this with 10 cases. No dimples, slam fires, or "chamber crimping"

Additionally, I primed two cases where I purposely left the primer slightly high HOPING I would get a controlled slam fire, but no such luck.. ;)

So, I'm not sure what getting a gunsmith to check will confirm. Short Chamber? Well, if so, then the original, manufacturer provided setup was short chambered. NO GO or FIELD fail? Impossible.
 

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Do not trust Forster gages, they are soft and conflict themselves. Also, HS gages have to be certified at regular intervals. This is not cheap, and is inconvenient. I'll get flamed for this, but "gunsmith's" have been making a fortune off of this, while fanning the flames of 'danger' on this topic since the '30s. Improper headspace will do one of three things. Insufficient, will not chamber (could lead to slamfire in substandard M14 type rifles, not a concern with quality receivers). Excessive 1. round will not fire, because firing pin will not contact primer, or 2. round fires, front half of case seals, back one third is forced back under 50,000 copper units of pressure, and either stretches beyond usability, or separates. This does not apply to the Mauser Controlled Feed, in which the extractor holds the case head against the bolt face. HTH,dave
Dave,

No flame from me. but there are some points of disagreement I have.

Back in the late 1980's, one of my Team Members described how "hard" his Uncle's DCM M1 Garand shot and how it cracked stocks so often and hot gas and pieces of brass came back in his face every so often. He talked about cracking four wooden stocks in only about 60 rounds fired. I told him to tell his Uncle to IMMEDIATELY stop shooting the rifle and bring it in to me to check headspace. I do not know how it happened to have gotten out of an arsenal and the rebuild inspection criteria for long term storage, but the chamber was so SHORT that it seemed like a nonexistant ".308 Short" rifle cartridge. I was amazed it would chamber a G.I. ball cartridge, but it certainly would.

One might be surprised how easy it is to chamber a new or NOS G.I. ball cartridge into a chamber with insufficient headspace. There is going to be more felt recoil, though some foks don't notice. There is going to be a louder report, but if you have excellent hearing protection on, you may not notice it either. I am not a mechanical engineer, but the PRESSURE of the 55,000 P.S.I. the cartridge normally endures goes way up when it is done. What that will cause is receiver and/or bolt failure way, WAY before the parts would fail with proper headspace. IOW, you may get away with it for a while until the heel of your receiver cracks or the bolt lug area of the receiver gets dinged up/set back. Insufficient headspace is not something you want to mess with on a gas gun. A bolt gun will handle insufficient headspace better than a gas gun because it is inherently a MUCH stronger action. However, firing a lot of rounds in a bolt gun with insuffiicient headspace will also cause undue wear and tear on the receiver and bolt out faster as well.

With excessive headspace, we can also run into some real problems with semi Auto M14's because folks use BOTH .308 and 7.62mm ammo in them. That is not a problem when the rifle is chambered to use both. However, if you have a barrel and bolt that headspaces to say 1.640 to 1.643 which is fine for NATO spec thicker brass, you are just asking for cases to rupture and hot gas and pieces of brass to come back into your face when you use softer commercial .308 brass or cartridges.

I absolutely do not recommend swapping an SAinc. bolt with a G.I. bolt when the barrel is G.I. as you usually run into too short headspace - UNTIL AND UNLESS you use quality headspace gages to check it. Now if the barrel is not chrome lined, one MIGHT be OK, but I still most heartedly advise folks to check headspace anyway.
 

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Discussion Starter · #10 ·
Dave,

No flame from me. but there are some points of disagreement I have.

Back in the late 1980's, one of my Team Members described how "hard" his Uncle's DCM M1 Garand shot and how it cracked stocks so often and hot gas and pieces of brass came back in his face every so often. He talked about cracking four wooden stocks in only about 60 rounds fired. I told him to tell his Uncle to IMMEDIATELY stop shooting the rifle and bring it in to me to check headspace. I do not know how it happened to have gotten out of an arsenal and the rebuild inspection criteria for long term storage, but the chamber was so SHORT that it seemed like a nonexistant ".308 Short" rifle cartridge. I was amazed it would chamber a G.I. ball cartridge, but it certainly would.

One might be surprised how easy it is to chamber a new or NOS G.I. ball cartridge into a chamber with insufficient headspace. There is going to be more felt recoil, though some foks don't notice. There is going to be a louder report, but if you have excellent hearing protection on, you may not notice it either. I am not a mechanical engineer, but the PRESSURE of the 55,000 P.S.I. the cartridge normally endures goes way up when it is done. What that will cause is receiver and/or bolt failure way, WAY before the parts would fail with proper headspace. IOW, you may get away with it for a while until the heel of your receiver cracks or the bolt lug area of the receiver gets dinged up/set back. Insufficient headspace is not something you want to mess with on a gas gun. A bolt gun will handle insufficient headspace better than a gas gun because it is inherently a MUCH stronger action. However, firing a lot of rounds in a bolt gun with insuffiicient headspace will also cause undue wear and tear on the receiver and bolt out faster as well.

With excessive headspace, we can also run into some real problems with semi Auto M14's because folks use BOTH .308 and 7.62mm ammo in them. That is not a problem when the rifle is chambered to use both. However, if you have a barrel and bolt that headspaces to say 1.640 to 1.643 which is fine for NATO spec thicker brass, you are just asking for cases to rupture and hot gas and pieces of brass to come back into your face when you use softer commercial .308 brass or cartridges.

I absolutely do not recommend swapping an SAinc. bolt with a G.I. bolt when the barrel is G.I. as you usually run into too short headspace - UNTIL AND UNLESS you use quality headspace gages to check it. Now if the barrel is not chrome lined, one MIGHT be OK, but I still most heartedly advise folks to check headspace anyway.
No usgi barrel. But let's look at the specific circumstances I have. The existing bolt and new GI bolt chamber my test cases and rounds exactly the same. I don't think I have to worry about excessive headspace as the rifle is brand new, and some of the test rounds chamber tightly (with both the existing bolt and nos winnie bolt). I have had no issues with the existing bolt.

Nevertheless, I am purchasing go and no gages. They are certainly cheap enough.
 

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Forster Gages

I don't know how many times I've seen comments about Forster gages being soft, out of spec, etc., but I've been using a full set of Forster Match Head Space Gages for over twenty years without problems. I have checked them against others including new GI gages and found no differences in the HS readings. I believe Forster gages are as good as any.
 

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I have had issues with Forster headspace gages and will absolutely not trust them. In 1989, I sent two sets of brand new .30-06 Gages into the Calibration Laboratory at Marine Corps Logistics Base, Albany, GA. Not ONE of the 6 headspace gages was close to being right. I had to get four gages exchanged until we finally had two complete sets that were correctly calibrated and Albany ground the two GO's and two NO GO gages to the correct length. Then when I got back to the RTE Shop in the early 90's we sent ALL our headspace gages in for calibration. Clymer and Pacific gages passed calibration inspection with flying colors - all the Forsters FLUNKED.

I do still have one Forster .308 gage is that is FULL two thousandths shorter than stated for a .308 Field Reject Gage. Since I know what length it is, it sometimes comes in handy.

I also have a set of Forster NM headspace gages for the AR 15, they aren't right either, when checked against other gages. I am not going to waste my money sending those in for calibration. These gages were a gift. Had I been the one who spent the money for them, I would have returned them for my money back.

That's why I recommend Clymer and Pacific Gages.
 

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No usgi barrel. But let's look at the specific circumstances I have. The existing bolt and new GI bolt chamber my test cases and rounds exactly the same. I don't think I have to worry about excessive headspace as the rifle is brand new, and some of the test rounds chamber tightly (with both the existing bolt and nos winnie bolt). I have had no issues with the existing bolt.

Nevertheless, I am purchasing go and no gages. They are certainly cheap enough.
There are only two gages you really need - that's the GO and Field Reject gages. The NO GO is shorter than the Field Reject and is only really necessary/useful if you are actually cutting chambers for Headspace. If you want to shoot both .308 and 7.62mm in the rifle, then I would use the GO and Field Reject gages for .308 Win.
 

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Gus, have you had occasion to use Manson gauges? Dave trained under Clymer and says that he makes his gauges (and reamers) to Clymer's print(s). I'm just curious; I've bought his reamers but not his headspace gauges.
 

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Gus, have you had occasion to use Manson gauges? Dave trained under Clymer and says that he makes his gauges (and reamers) to Clymer's print(s). I'm just curious; I've bought his reamers but not his headspace gauges.
I have not personally used any of his headspace gages, but I have heard good things about them from people I respect. The only reason I don't include Manson in my first two choices is solely because I have never used them and thus can not give them my personal recommendation. That does not mean there is anything wrong with them, though.
 

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Discussion Starter · #17 ·
There are only two gages you really need - that's the GO and Field Reject gages. The NO GO is shorter than the Field Reject and is only really necessary/useful if you are actually cutting chambers for Headspace. If you want to shoot both .308 and 7.62mm in the rifle, then I would use the GO and Field Reject gages for .308 Win.
The rifle is new. The lugs on the Winnie bolt have absolutely no wear on them, so, as a recently purchased rifle, I want to make sure it passes NO GO. Based on what I've observed already, it should pass GO and have plenty of meat to also pass a NO GO.

I have GO and FIELD gages in 30-06, since I have a bunch of Garands, a 1903A3, and two 1903Aforgeries, some of which I've rebarreled, and wouldn't expect all of them to pass NO GO, especially the field grade rifles.
 

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The rifle is new. The lugs on the Winnie bolt have absolutely no wear on them, so, as a recently purchased rifle, I want to make sure it passes NO GO. Based on what I've observed already, it should pass GO and have plenty of meat to also pass a NO GO.

I have GO and FIELD gages in 30-06, since I have a bunch of Garands, a 1903A3, and two 1903Aforgeries, some of which I've rebarreled, and wouldn't expect all of them to pass NO GO, especially the field grade rifles.
What you may not understand is that SAinc. bolts do not always or necessarily have the same dimensions as a G.I. bolt. They should, but they don't. Usually a G.I. bolt is longer than an SAinc. bolt and that is why you have to make sure to check with the GO gage as well.
 

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It's probably more effective for me to just buy the gauges and test it myself. Which ones do you recommend?
Clymer gauges are the ones to use,get a GO and NO-GO if it closes on GO you are OK now if you want to find out exactly how deep the chamber is glue a piece of scotch tape on the end of the GO gauge which is two thousands of an inch thick and see if it closes on that or not that way you can tell how many thousands you are past the SAAMI GO Gauge.
 
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