Bulge in barrel maybe responsible for innacuracy?

[john]

Okay, bought a second 1928A1 last year and it came with a small bulge in the barrel as well as a new takeoff barrel in perfect shape.

FYI, this was a J Curtis Earl gun and is pictured on page 17 of his 1986 - second printing catalog, a Savage with s/n S-541758. Very clean and in great shape.

 

Took it out to fire it for the first time yesterday and it runs like a Swiss watch....nary a hiccup out of place!

The problem is, at 50 yards it's shooting a couple feet high and a foot right.

Funny thing - the bulge in the barrel is (looking down through the sights) at about 1 o'clock, the same direction as the bullets impact.

Is it possible that the bulge at 1 o'clock is causing the bullet to fly high and right, either harmonically or by shifting pressure at the base of the bullet, or for some other oddball reason??

 

Planning to bench and sandbag it and document targets carefully, then will replace the barrel and run through that procedure again to see, but wondering if anyone has ever noticed this as an anomaly on their guns in the past?

[john]

Incidentally, it wasn't fired for years but was still dirty when I bought it. The slits in the compensator were heavily carboned up on the right side, but much less on the left. I chipped that residue away carefully but that heavier buildup in the right only was odd.....

[Taliaferro]

Are the firing results before or after cleaning the compensator?

 

Tracie

[richard w.]

I don't have that book. Is it an "L" rear sight?

 

Peep is zeroed for 100 yards and notch 250, so it would shoot high at 50 yards.

[john]

Fired after cleaning out the comp. Gun is a late Savage 28 and has an "L" sight, but that and front sight appear to be centered properly.

Refinished probably post war as the barrel was parked (or heavy ixide?) Black.

 

Bulge seems to protrude up at 1 o'clock and not as much on other sides.

 

Just seemed funny as my early AO 1928 shoots spot-on, but has a flip up Lyman.

[Taliaferro]

I am not an expert accuracy of bulge barrels, but from what I have read, the crown of the barrel

and the comp porting will have more effect on the accuracy than a bulge.

 

I would put a laser bore sight into the chamber and check the accuracy of the sight first. You can buy .45

chamber lasers pretty cheep.

 

T

[jim c 351]

John,

You might consider 2 factors separately.

#1

How close your gun will group its shots.

#2

How far off target the group hits from point of aim.

 

One of my Winchester 32 self loaders has a bulge near the muzzle , but it will place 5 shots within 6 inches at 100 yards. Considering the open sights I rate that as accurate.

So how close will your gun group its shots?? Compare this group size to your other 28A1.

 

Next , how far off target are your groups hitting?? As Richard said, Thompsons regulated for 100 yards. So they will hit high at 50 yards. If you ever attended one of the Thompson Collectors shoots, one phase is 20 shots semi at 50 yards. The loosing targets will show the groups hit high on the silhouette targets.

As far as 12 inches right at 50 yards is concerned, that is one of the short comings of the "L" sight. My 28A1 had a "L" sight and grouped 5 inches right at 25 yards. At 50 yards it would have equaled your gun. I solved that problem by installing a adjustable rear sight.

 

My guess would be, the bulge is not as much of a problem as the "L" sight.

Jim C

Edited March 27, 2019 by jim c 351

[gijive]

While not directly answering the question about whether the bulge or the L sight contributes to the inaccuracy of your gun, I found this picture recently while perusing WWII films on YouTube and found it interesting. Either the gun was dropped on the unprotected L sight or the sight was purposely lowered to adjust for the gun shooting somewhat high? Anyway, I found it to be an interesting photo of either the shortcomings of the unprotected L sight or wartime expediency.

 

 

 

[john]

Thanks all. I do know they shoot high at 50 and higher at 25 as have been to a couple shoots. My old AO took 2nd place at a shoot back in 2003(?) and it groups tightly, although it shoots dead center with rear sight down. When I rebarreled this I centered the front sight on a Mill with a dial indicator on each side of the blade....it's within maybe .0002 of being perfect!

The new Savage front sight hasn't been checked for that tolerance BUT (without sand bagging it) was, as I saw it, hitting all in a very small area on the berm....maybe 4-5 inches while my son shot singles. Very consistent.....but as I said, a foot right, two feet high at fifty yards. Guess maybe that's a thing with L-sights that aren't adjustable at all. At least it's consistent! AND the L-sights are a whole lot quicker to pick up with the eye....I can see why they replaced the adjustable Lyman's.

 

gijive, Love the image of the GI with a field-adjusted Close quarters combat rear sight....ya do what ya gotta do!

 

Again, the beast shoots well and as jim says, it probably has less to do with this than I thought but it does pose an interesting set of questions!

 

Maybe I'll leave this tube on awhile and have fun with it.....then when it wears out I'll add a Lyman flip sight along with the new barrel!

 

Thanks y'all!

 

john

[ron_brock]

John,

 

Two off the wall questions. Are the barrel and comp original? Is the gun original or is there any evidence of deactivation at some time?

 

Ron

[john]

Never deactivated - all looks great in and out but barrel is same finish as gun....and same finish pictured in the JC Earl 86 catalog (black park or dulite ...fine like dulite but that was never done in arsenal rebuilds..) and barrel/comp match gun.

Witness marks and proofs on barrel look maybe original or ordy replacement at some time.

[TSMGguy]

The beauty of the "L" sight was that it was made of mild steel, and was adjustable. Bend the rear sight post forward or back to lower the point of impact, or side to side to adjust in azimuth.

[reconbob]

For any gun to shoot 2 feet high at 50 yards would mean that the rear sight is too low causing the

barrel to be pointed too high when sighted, OR, the barrel is bent, OR the receiver is bent OR some

combination of the two. It might also help to have someone else fire the gun and see if they get the

same result.

It is difficult to check the straightness of the barrel without removing it from the receiver.

When a receiver is machined from a solid bar most of the cross section is machined away

where the ejection port and magazine cutout are. If the steel is not stress relieved before machining

the front of the receiver will bend up due to the stresses in the steel. Now, if this is a G.I. gun

of course the receiver was stress relieved but things can happen over 75 years. I have encountered

receivers and trigger frames that have become bent over time and had to be pressed back into

straightness and flatness.

Here at the shop we would check the flatness of the receiver by placing it top down on a granite

surface plate and checking to see if the entire top surface of the receiver sits flat on the plate or

if light can be seen or feeler gages passed under the receiver.

Of course you do not have a surface plate but a flat kitchen counter or table can be used.

Place the receiver top side down on the corner of the table or counter so the rear sight and the

front sight do not contact the surface of the table. Place a 1/2" wide strip of newspaper which will

be about 0.0015" thick where the middle of the ejection port is. The paper should be pinched by the

receiver and you should not be able to pull it out from under the receiver when pressing down on

the receiver. You can also put a light in such a way as to see it light shines under the receiver. If

the paper is not pinched, and/or if you see light keep adding strips of paper and see how many

you have to use before they get pinched and held in place and you'll get an idea how much its bent.

If the receiver is bent it may not be due to stress relieve it may be that some time during the life

of the gun it was subjected to prying or bending forces for whatever reason.

If the receiver is bent the fix is to bend it back. Not for the faint of heart, but it can be done.

It may turn out that the receiver is not bent but something is wrong somewhere and likely

not the bulge....

 

Bob

Edited March 30, 2019 by reconbob

[Petroleum 1]

I think that GI is using the charging handle as his sight lol

[huggytree]

he's 1 1/2 above that....looks like a staged movie picture and not a soldier trying to hit something.....yelling and unloading 30 rounds at the same time

 

he doesnt have a machine gun stance going

[gijive]

he's 1 1/2 above that....looks like a staged movie picture and not a soldier trying to hit something.....yelling and unloading 30 rounds at the same time

 

he doesnt have a machine gun stance going

The screen capture is from motion picture film. The soldier is actually firing the gun in the motion picture. Whether he is firing at the enemy or squeezed off a few rounds for the cameraman is unknown, but is from actual combat film from Germany in 1945. I captured the screenshot when he pulled away from the sight after firing to better illustrate the bent sight.

 

Here is another capture.

 

[gijive]

For any gun to shoot 2 feet high at 50 yards would mean that the rear sight is too low causing the

barrel to be pointed too high when sighted, OR, the barrel is bent, OR the receiver is bent OR some

combination of the two. It might also help to have someone else fire the gun and see if they get the

same result.

Actually, I believe it is just the opposite. If the gun shoots high, lowering the rear sight will drop the point of impact.

 

https://en.wikiversity.org/wiki/How_to_adjust_an_iron_sight

[reconbob]

Oops, you are correct. I got it backwards. To shoot high, rear sight too high.

 

Bob