ABSOLUTELY ESSENTIAL TO SHOOTING ANY BREAK OPEN GUN!
If you think for one second you can combine one each of 100's of thousands of barrels and frames, millions of rounds of ammunition both factory and hap hazardly sized handloads and have it work right every time, you are DREAMING!
It is just not at all reasonable to expect all the tolerances involved to add up to a proper fit. It is just not going to happen in this lifetime.
It is also not reasonable to expect a chamber to be cut to a proper depth, then you feed it ammo that is either too long or too short and expect the gun to work right.
KNOW PRECISELY what the headspace is with factory ammo, new brass, or handloads!
Take the guess work out of size die adjustment and bullet seating depth!
Get it right with the Bellm Headspace Indicator! YOUR break open barrel is the "gauge" and always has been, but you have not had a good way to take measurements from it. Now you can!
Measure actual headspace of the ammunition you are shooting in any given barrel and frame combination as well as measuring the distance from the rifling to the breechface to arrive at bullet seating depth.
However you go about it, being able to measure headspace and bullet seating depth in break open guns is an absolute must. Thousands of dollars are wasted swapping perfectly good barrels around in quest of accuracy when the only problem with the barrel is headspace that is easily corrected by taking a few simple measurements and making some minor changes in your procedures.
Learn how to measure it, take the necessary steps to get correct headspace, and get the full potential and reliable functioning of all your break-open guns.
Complete instructions in the store menu item "Headspace, How to Get It Right" above "Bellm Headspace Indicator," but here is the headspace "short course."
First, forget everything you think you know about headspace from magazines and books, then start over!
The usual talk about headspace is bogus, very confusing and misleading. It is usually referred to as a length in the chamber or the ammo. It is NOT a length. It is the actual space between the cartridge case head and the breechface, in TC guns the firing pin bushing.
The lengths referred to in the books, etc. DETERMINE headspace, but they themselves are not "head" "space," which you can very readily measure for any type of round.
Make it easy on yourself. Forget about any headspace related measurements found in books or drawings, etc. Measure the actual space between case head and firing pin bushing.
First close the barrel on successively thicker feeler gauge blades until the barrel will grip one, then back down to the next thinner blade that will slide out from behind the closed barrel. Call the one that just will slide out the barrel-to-frame gap. If the thinnest blade is gripped, call the barrel-to-frame gap zero.
Install the round base on the dial indicator with the end down that matches the breech diameter of the barrel you are working with..... 1" down for Encore/Pro Hunter, smaller 13/16" end down for Contender/G2.
Set your assembled Bellm Headspace Indicator on a smooth, flat surface, then rotate the dial to line up the needle with "0".
Drop a sized case or loaded round into the empty barrel, pressing it in all the way with your fingers so it is fully seated forward in the barrel.
Place the indicator and base on the end of the barrel, matching the outside diameter of the base with the outside diameter of the barrel. This positions the indicator quill off center, just outside of the primer pocket on the solid surface of the case head.
The indicator then reads in thousandths how much the case head is above or below the end of the barrel, or reads "0" if the case head is dead flush with the end of the barrel.
Compare this reading with the barrel-to-frame gap measurement you got with the feeler gauge blades.
The following examples use .004" as the gap measurement, but any given barrel-to-frame gap can be anything from .0000" to a full 1/8th of an inch. The amount of the gap has no bearing on the quality of the barrel, good or bad, but you must know what the gap measures to know how far the case must stick out of the barrel, or, if the gap is zero, know that it must be kept dead flush with the end of the barrel.
Gap is .004"
Case is dead flush with end of barrel.
Headspace is then .004"
Gap is .004"
Case sticks out of the barrel .002"
Space remaining between case head and firing pin bushing is
.004" minus .002" leaving .002" "head" "space."
Gap is .004"
Case head is .003" BELOW the end of the barrel.
So, with .004" to the end of the barrel, plus .003" BELOW the end of the barrel, the "space" at the case "head" is .004" plus .003" for a total of .007" which is considered EXCESS HEADSPACE and must be corrected to stop misfires, case stretching, poor accuracy. Shimming the firing pin bushing for use with new brass or factory ammo is necessary, or when resizing fired cases, adjust the size die to NOT push shoulders back to far.
Gap is .004"
Case sticks out of the barrel .009", which is not uncommon due to the frame flexing and the case stretching in body length along with it.
You have NO "space" at the "head." You must have SOME space.
This is most common with reloaded ammo. Seldom are chambers too shallow for factory ammo or new brass.
You must bump case shoulders back with the size die so they stick out of the barrel something less than .004" so the barrel can lock up completely in the frame and to prevent the frame from pushing the case in and up in the chamber, out of alignment with the chamber and bore and also putting a pre-load on the frame that varies from shot to shot with the usual effect of vertical stringing of shots.
Since some die manufacturers tend to make size dies deep enough inside so you cannot push shoulders back too far, the result is you may not be able to push them back far enough to get back to the original dimensions needed, in which case the size die must be shortened so it can push the shoulders back the proper amount as indicated by a "space" between the case "head" and firing pin bushing measuring between .001" and .003".
.001" is the desired minimum clearance at the case head, but is hard to hold closely. Anything up to about .003" is good and does not result in an excessive amount of case stretching while permitting best accuracy and function.
"Space" between cartridgde case "head" and firing pin bushing exceeding about .004" is more than desireable and will result in more stretching of the case than necessary with the result case life will be reduced.
"Space" between the case "head" and firing pin bushing exceeding .006" will stretch cases, give erratic ignition & poor accuracy, and if much more than .006" will result in misfires, even with a stronger hammer spring.
To find distance from rifling to firing pin bushing, measure where the empty case head is in relatinship to the end of the barrel, seat a bullet out too far, measure again, then in small careful increments seat the bullet deeper in the case until the case head returns back to the same depth in the chamber that it did without a bullet. At this point the bullet is no longer holding the round out of the chamber, but with it just touching the rifling, you now know what the overall cartridge length will be with that given bullet brand/weight/point form. Save that round for setting your seat die to the same overall length, then seat bullet however many thous. off the rifling you want to be. No further gadgets or widgets are necessary. Work directly from the barrel. The seat die stem serves to locate on the ogive of the bullet. You measure the change in overall length +/- from that point.
The Bellm Headspace Indicator bases alone are offered separately for those who either have dial indictors already or who already have ready sources of precision measuring equipment.
If you have your own dial indicator already or want to purchase your own indicator, this is an option for you. Get the base alone. The base is bored and reamed for the standard 3/8" indicator shank, and its length is for common dial indicators with 1/2" to 1" travel.
We can also supply on request the top quality brands such as Mitutoyo, Brown and Sharp, and Starrett.
(DIAL INDICATOR QUALITY UPGRADES, POSTED WHEN AVAILABLE)